aboutsummaryrefslogtreecommitdiffstats
path: root/docs/usermanual/chapters/recipes.xml
blob: acb0705c90144398bdd1c83dc58203570fd31750 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
<?xml version="1.0" encoding="UTF-8"?>
<chapter id="chapter_recipes" xreflabel="Recipes chapter">
  <title>Recipes</title>

  <section id="recipes_introduction" xreflabel="introduction">
    <title>Introduction</title>

    <para>A bitbake recipe is a set of instructions that describes what needs
    to be done to retrieve the source code for some application, apply any
    necessary patches, provide any additional files (such as init scripts),
    compile it, install it and generate binary packages. The end result is a
    binary package that you can install on your target device, and maybe some
    intermediate files, such as libraries and headers, which can be used when
    building other applications.</para>

    <para>In many ways the process is similar to creating .deb or .rpm
    packages for your standard desktop distributions with one major difference
    - in OpenEmbedded everything is being cross-compiled. This often makes the
    task far more difficult (depending on how well suited the application is
    to cross compiling), than it is for other packaging systems and sometimes
    impossible.</para>

    <para>This chapter assumes that you are familiar with working with
    bitbake, including the work flow, required directory structures and bitbake
    configuration. If you are not familiar with these
    then first take a look at the chapter on bitbake usage.</para>
  </section>

  <section id="recipes_syntax" xreflabel="syntax">
    <title>Syntax of recipes</title>

    <para>The basic items that make up a bitbake recipe file are:</para>

    <variablelist>
      <varlistentry>
        <term>functions</term>

        <listitem>
          <para>Functions provide a series of actions to be performed.
          Functions are usually used to override the default implementation of
          a task function, or to compliment (append or prepend to an existing
          function) a default function. Standard functions use sh shell
          syntax, although access to OpenEmbedded variables and internal
          methods are also available.</para>

          <para>The following is an example function from the sed
          recipe:</para>

          <para><screen>do_install () {
    autotools_do_install
    install -d ${D}${base_bindir}
    mv ${D}${bindir}/sed ${D}${base_bindir}/sed.${PN}
}</screen>It is also possible to implement new functions, that are not
          replacing or complimenting the default functions, which are called
          between existing tasks. It is also possible to implement functions
          in python instead of sh. Both of these options are not seen in the
          majority of recipes.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>variable assignments and manipulations</term>

        <listitem>
          <para>Variable assignments allow a value to be assigned to a
          variable. The assignment may be static text or might include the
          contents of other variables. In addition to assignment, appending
          and prepending operations are also supported.</para>

          <para>The following example shows some of the ways variables can be
          used in recipes:<screen>S = "${WORKDIR}/postfix-${PV}"
PR = "r4"
CFLAGS += "-DNO_ASM"
SRC_URI_append = "file://fixup.patch"</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>keywords</term>

        <listitem>
          <para>Only a few keywords are used in bitbake recipes. They are used
          for things such as including common functions
          (<emphasis>inherit</emphasis>), loading parts of a recipe from other
          files (<emphasis>include</emphasis> and
          <emphasis>require</emphasis>) and exporting variables to the
          environment (export).</para>

          <para>The following example shows the use of some of these
          keywords:<screen>export POSTCONF = "${STAGING_BINDIR}/postconf"
inherit autoconf
require otherfile.inc</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>comments</term>

        <listitem>
          <para>Any lines that begin with a # are treated as comment lines and
          are ignored.<screen># This is a comment</screen></para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>The following is a summary of the most important (and most commonly
    used) parts of the recipe syntax:</para>

    <variablelist>
      <varlistentry>
        <term>Line continuation: \</term>

        <listitem>
          <para>To split a statement over multiple lines you should place a \ at
          the end of the line that is to be continued on the next line.</para>

          <screen>VAR = "A really long \
       line"</screen>

          <para>Note that there must not be anything (no spaces or tabs) after
          the \.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Using variables: ${...}</term>

        <listitem>
          <para>To access the contents of a variable you need to access it via
          <emphasis>${&lt;varname&gt;}</emphasis>:<screen>SRC_URI = "${SOURCEFORGE_MIRROR}/libpng/zlib-${PV}.tar.gz"</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Quote all assignments</term>

        <listitem>
          <para>All variable assignments should be quoted with double quotes.
          (It may work without them at present, but it will not work in the
          future).<screen>VAR1 = "${OTHERVAR}"
VAR2 = "The version is ${PV}"</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Conditional assignment</term>

        <listitem>
          <para>Conditional assignment is used to assign a value to a
          variable, but only when the variable is currently unset. This is
          commonly used to provide a default value for use when no specific
          definition is provided by the machine or distro configuration of the
          user's local.conf configuration.</para>

          <para>The following example:<screen>VAR1 ?= "New value"</screen>will
          set <emphasis role="bold">VAR1</emphasis> to <emphasis>"New
          value"</emphasis> if it is currently empty. However if it was already
          set it would be unchanged. In the following <emphasis
          role="bold">VAR1</emphasis> is left with the value
          <emphasis>"Original value"</emphasis>:<screen>VAR1 = "Original value"
VAR1 ?= "New value"</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Appending: +=</term>

        <listitem>
          <para>You can append values to existing variables using the
          <emphasis>+=</emphasis> operator. Note that this operator will add a
          space between the existing content of the variable and the new
          content.<screen>SRC_URI += "file://fix-makefile.patch"</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Prepending: =+</term>

        <listitem>
          <para>You can prepend values to existing variables using the
          <emphasis>=+</emphasis> operator. Note that this operator will add a
          space between the new content and the existing content of the
          variable.<screen>VAR =+ "Starts"</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Appending: _append</term>

        <listitem>
          <para>You can append values to existing variables using the
          <emphasis>_append</emphasis> method. Note that this operator does
          not add any additional space, and it is applied after all the
          <emphasis>+=</emphasis>, and <emphasis>=+</emphasis> operators have
          been applied.</para>

          <para>The following example shows the space being explicitly added to
          the start to ensure the appended value is not merged with the
          existing value:<screen>SRC_URI_append = " file://fix-makefile.patch"</screen>The
          <emphasis>_append</emphasis> method can also be used with overrides,
          which results in the actions only being performed for the specified
          target or machine: [TODO: Link to section on overrides]<screen>SRC_URI_append_sh4 = " file://fix-makefile.patch"</screen>Note
          that the appended information is a variable itself, and therefore
          it's possible to use <emphasis>+=</emphasis> or
          <emphasis>=+</emphasis> to assign variables to the
          <emphasis>_append</emphasis> information:<screen>SRC_URI_append = " file://fix-makefile.patch"
SRC_URI_append += "file://fix-install.patch"</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Prepending: _prepend</term>

        <listitem>
          <para>You can prepend values to existing variables using the
          _prepend method. Note that this operator does not add any additional
          space, and it is applied after all the <emphasis>+=</emphasis>, and
          <emphasis>=+</emphasis> operators have been applied.</para>

          <para>The following example shows the space being explicitly added to
          the end to ensure the prepended value is not merged with the
          existing value:<screen>CFLAGS_prepend = "-I${S}/myincludes "</screen>The
          <emphasis>_prepend</emphasis> method can also be used with
          overrides, which result in the actions only being performed for the
          specified target or machine: [TODO: Link to section on
          overrides]<screen>CFLAGS_prepend_sh4 = " file://fix-makefile.patch"</screen>Note
          that the appended information is a variable itself, and therefore
          it's possible to use <emphasis>+=</emphasis> or
          <emphasis>=+</emphasis> to assign variables to the
          <emphasis>_prepend</emphasis> information:<screen>CFLAGS_prepend = "-I${S}/myincludes "
CFLAGS_prepend += "-I${S}/myincludes2 "</screen>Note also the lack of a space
          when using += to append to a prepend value - remember that the +=
          operator adds space itself.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Spaces vs tabs</term>

        <listitem>
          <para>Spaces should be used for indentation, not hard tabs. Both
          currently work, however it is a policy decision of OE that spaces
          always be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Style: oe-stylize.py</term>

        <listitem>
          <para>To help with using the correct style in your recipes there is
          a python script in the contrib directory called
          <emphasis>oe-stylize.py</emphasis> which can be used to reformat
          your recipes to the correct style. The output will contain a list of
          warnings (to let you know what you did wrong) which should be edited
          out before using the new file.<screen>$ <command>contrib/oe-stylize.py</command> myrecipe.bb &gt; fixed-recipe.bb
vi fixed-recipe.bb
mv fixed.recipe.bb myrecipe.bb</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Using python for complex operations: ${@...}</term>

        <listitem>
          <para>For more advanced processing it is possible to use python code
          during variable assignments, for doing search and replace on a
          variable for example.</para>

          <para>Python code is indicated by a proceeding @ sign in the
          variable assignment.<screen>CXXFLAGS := "${@'${CXXFLAGS}'.replace('-frename-registers', '')}"</screen>More
          information about using python is available in the <xref
          linkend="recipes_advanced_python" /> section.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Shell syntax</term>

        <listitem>
          <para>When describing a list of actions to take, shell syntax is used
          (as if you were writing a shell script). You should ensure that your
          script works with a generic sh and not require any bash (or
          other shell) specific functionality. The same applies to various
          system utilities (sed, grep, awk etc) that you may wish to use. If
          in doubt you should check with multiple implementations - including
          those from busybox.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>For a detailed description of the syntax for the bitbake recipe
    files you should refer to the bitbake user manual.</para>
  </section>

  <section id="recipes_versioning" xreflabel="versioning">
    <title>Recipe naming: Names, versions and releases</title>

    <para>Recipes in OpenEmbedded use a standard naming convention that
    includes the package name and version number in the filename. In addition
    to the name and version there is also a release number, which indicates
    changes to the way the package is built and/or packaged. The release
    number is contained within the recipe itself.</para>

    <para>The expected format of recipe name is:<screen>&lt;package-name&gt;_&lt;version&gt;.bb</screen></para>

    <para>where <emphasis>&lt;package-name&gt;</emphasis> is the name of the
    package (application, library, module, or whatever it is that is being
    packaged) and <emphasis>version</emphasis> is the version number.</para>

    <para>So a typical recipe name would be:<screen>strace_4.5.14.bb</screen>which
    would be for version <emphasis>4.5.14</emphasis> of the
    <emphasis>strace</emphasis> application.</para>

    <para>The release version is defined via the package release variable, PR,
    contained in the recipe. The expected format is:<screen>r&lt;n&gt;</screen>where
    <emphasis>&lt;n&gt;</emphasis> is an integer number starting from 0
    initially and then incremented each time the recipe, or something that
    effects the recipe, is modified. So a typical definition of the release
    would be:<screen>PR = "r1"</screen>to specify release number
    <emphasis>1</emphasis> (the second release, the first would have been
    <emphasis>0</emphasis>). If there is no definition of PR in the recipe
    then the default value of "r0" is used.</para>

    <para><note>
        <para>It is good practice to always define PR in your recipes, even
        for the <emphasis>"r0"</emphasis> release, so that when editing the
        recipe it is clear that the PR number needs to be updated.</para>

        <para>You should always increment PR when modifying a recipe.
        Sometimes this can be avoided if the change will have no effect on the
        actual packages generated by the recipe, such as updating the SRC_URI
        to point to a new host. If in any doubt then you should increase the
        PR regardless of what has been changed.</para>

        <para>The PR value should never be decremented. If you accidentally
        submit a large PR value for example then it should be left at the
        value and just increased for new releases, not reset back to a lower
        version.</para>
      </note></para>

    <para>When a recipe is being processed some variables are automatically
    set based on the recipe file name and can be used for other purposes from
    within the recipe itself. These include:</para>

    <variablelist>
      <varlistentry>
        <term>PN</term>

        <listitem>
          <para>The package name. Determined from the recipe filename -
          everything up until the first underscore is considered to be the
          package name. For the <command>strace_4.5.14.bb</command> recipe the
          PN variable would be set to <emphasis>"strace"</emphasis>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>PV</term>

        <listitem>
          <para>The package version. Determined from the recipe filename -
          everything between the first underscore and the final .bb is
          considered to be the package version. For the
          <command>strace_4.5.14.bb</command> recipe the PV variable would be
          set to <emphasis>"4.5.14"</emphasis>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>PR</term>

        <listitem>
          <para>The package release. This is explicitly set in the recipe.
          It defaults to "<emphasis>r0"</emphasis> if not set.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>P</term>

        <listitem>
          <para>The package name and versions separated by a hyphen.<screen>P = "${PN}-${PV}"</screen></para>

          <para>For the <command>strace_4.5.14.bb</command> recipe the P
          variable would be set to
          <emphasis>"strace-4.5.14"</emphasis>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>PF</term>

        <listitem>
          <para>The package name, version and release separated by
          hyphens.<screen>PF = "${PN}-${PV}-${PR}"</screen></para>

          <para>For the <command>strace_4.5.14.bb recipe</command>, with PR
          set to <emphasis>"r1"</emphasis> in the recipe, the PF variable
          would be set to <emphasis>"strace-4.5.14-r1"</emphasis>.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>While some of these variables are not commonly used in recipes (they
    are used internally though) both PN and PV are used a lot.</para>

    <para>In the following example we are instructing the packaging system to
    include an additional directory in the package. We use PN to refer to the
    name of the package rather than spelling out the package name:<screen>FILES_${PN} += "${sysconfdir}/myconf"</screen></para>

    <para>In the next example we are specifying the URL for the package
    source, by using PV in place of the actual version number it is possible
    to duplicate, or rename, the recipe for a new version without having to
    edit the URL:<screen>SRC_URI = "ftp://ftp.vim.org/pub/vim/unix/vim-${PV}.tar.bz2"</screen></para>
  </section>

  <section id="recipes_variables" xreflabel="variables">
    <title>Variables</title>

    <para>One of the most confusing parts of bitbake recipes for new users is
    the large amount of variables that appear to be available to change and/or
    control the behaviour of some aspect of the recipe. Some variables, such
    as those derived from the file name are reasonably obvious, others are not
    at all obvious.</para>

    <para>There are several places where these variables are derived from
    and/or used:</para>

    <orderedlist>
      <listitem>
        <para>A large number of variables are defined in the bitbake
        configuration file conf/bitbake.conf - it's often a good idea to look
        through that file when trying to determine what a particular variable
        means.</para>
      </listitem>

      <listitem>
        <para>Machine and distribution configuration files in conf/machine and
        conf/distro will sometimes define some variables specific to the
        machine and/or distribution. You should look at the appropriate files
        for your targets to see if anything is being defined that effects the
        recipes you are building.</para>
      </listitem>

      <listitem>
        <para>Bitbake itself will define some variables. The FILE variable
        that defines the name of the bitbake recipe being processed is set by
        bitbake itself for example. Refer to the bitbake manual for more
        information on the variables that bitbake sets.</para>
      </listitem>

      <listitem>
        <para>The classes that are used via the inherit keyword define
        and/or use the majority of the remaining variables. A class is like
        a library that contains parts of a bitbake recipe that is used by
        multiple recipes. To make them usable in more situations they often
        include a large number of variables to control how the class
        operates.</para>
      </listitem>
    </orderedlist>

    <para>Another important aspect is that there are three different types of
    things that binaries and libraries are used for and they often have
    different variables for each. These include:</para>

    <variablelist>
      <varlistentry>
        <term>target</term>

        <listitem>
          <para>Refers to things built for the target and are expected to be run
          on the target device itself.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>native</term>

        <listitem>
          <para>Refers to things built to run natively on the build host
          itself.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>cross</term>

        <listitem>
          <para>Refers to things built to run natively on the build host
          itself, but produce output which is suitable for the target device.
          Cross versions of packages usually only exist for things like
          compilers and assemblers - i.e. things which are used to produce
          binary applications themselves.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </section>

  <section id="recipes_header" xreflabel="header">
    <title>Header</title>

    <para>Practically all recipes start with a header section which describes
    various aspects of the package that is being built. This information is
    typically used directly by the package format (such as ipkg or deb) as
    meta data used to describe the package.</para>

    <para>Variables used in the header include:</para>

    <variablelist>
      <varlistentry>
        <term>DESCRIPTION</term>

        <listitem>
          <para>Describes what the software does. Hopefully this gives enough
          information to a user to know if it's the right application for
          them.</para>

          <para>The default description is: <emphasis>"Version ${PV}-${PR} of
          package ${PN}"</emphasis>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>HOMEPAGE</term>

        <listitem>
          <para>The URL of the home page of the application where new releases
          and more information can be found.</para>

          <para>The default homepage is <emphasis>"unknown"</emphasis>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>SECTION</term>

        <listitem>
          <para>The section is used to categorize the application into a
          specific group. Often used by GUI based installers to help users
          when searching for software.</para>

          <para>See <xref linkend="section_variable" /> for a list of the
          available sections.</para>

          <para>The default section is <emphasis>"base"</emphasis>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>PRIORITY</term>

        <listitem>
          <para>The default priority is
          <emphasis>"optional"</emphasis>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>LICENSE</term>

        <listitem>
          <para>The license for the application. If it is not one of the
          standard licenses then the license itself must be included
          (where?).</para>

          <para>As well as being used in the package meta-data the license is
          also used by the src_distribute class.</para>

          <para>The default license is <emphasis>"unknown"</emphasis>.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </section>

  <section id="recipes_sources" xreflabel="sources">
    <title>Sources: Downloading, patching and additional files</title>

    <para>A recipe's purpose is to describe how to take a software package and
    build it for your target device. The location of the source file (or
    files) is specified via the <xref linkend="src_uri_variable" /> in the
    recipe. This can describe several types of URIs, the most common
    are:</para>

    <variablelist>
      <varlistentry>
        <term>http and https</term>

        <listitem>
          <para>Specifies files to be downloaded. A copy is stored locally so
          that future builds will not download the source again.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>cvs, svn and git</term>

        <listitem>
          <para>Specifies that the files are to be retrieved using the
          specified version control system.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>files</term>

        <listitem>
          <para>Plain files which are included locally. These can be used for
          adding documentation, init scripts or any other files that need to
          be added to build the package under openembedded.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>patches</term>

        <listitem>
          <para>Plain files which are treated as patches and
          automatically applied.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>If an http, https or file URI refers to a compressed file, an archive
    file or a compressed archive file, such as .tar.gz or .zip, then the files
    will be uncompressed and extracted from the archive automatically.</para>

    <para>Archive files will be extracted from within the working directory,
    <emphasis role="bold">${WORKDIR}</emphasis> and plain files will be copied
    into the same directory. Patches will be applied from within the unpacked
    source directory, <emphasis role="bold">${S}</emphasis>. (Details on these
    directories is provided in the next section.)</para>

    <para>The following example from the havp recipe shows a typical <emphasis
    role="bold">SRC_URI</emphasis> definition:<screen>SRC_URI = "http://www.server-side.de/download/havp-${PV}.tar.gz \
           file://sysconfdir-is-etc.patch \
           file://havp.init \
           file://doc.configure.txt \
           file://volatiles.05_havp"</screen></para>

    <para>This describes several files</para>

    <variablelist>
      <varlistentry>
        <term>http://www.server-side.de/download/havp-${PV}.tar.gz</term>

        <listitem>
          <para>This is the URI of the havp source code. Note the use of the
          <emphasis role="bold">${PV}</emphasis> variable to specify the
          version. This is done to enable the recipe to be renamed for a new
          version without the need to edit the recipe itself. Because this is
          a .tar.gz compressed archive the file will be decompressed and
          extracted in the working dir <emphasis
          role="bold">${WORKDIR}</emphasis>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>file://sysconfdir-is-etc.patch</term>

        <listitem>
          <para>This is a local file that is used to patch the extracted
	  source code. If a filename ends in .patch or .diff then this is
	  treated as patch file and applied with striplevel 1. The
          patch will be applied from the unpacked source directory, <emphasis
          role="bold">${S}</emphasis>. In this case <emphasis
          role="bold">${S}</emphasis> will be <emphasis
          role="bold">${WORKDIR}/havp-0.82</emphasis>, and luckily the
          <emphasis role="bold">havp-0.82.tar.gz</emphasis> file extracts
          itself into that directory (so no need to explicitly change
          <emphasis role="bold">${S}</emphasis>).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>file://havp.init file://doc.configure.txt
        file://volatiles.05_havp"</term>

        <listitem>
          <para>These are plain files which are just copied into the working
          directory <emphasis role="bold">${WORKDIR}</emphasis>. These are
          then used during the install task in the recipe to provide init
          scripts, documentation and volatiles configuration information for
          the package.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>Full details on the <emphasis role="bold">SRC_URI</emphasis>
    variable and all the support URIs are available in the <xref
    linkend="src_uri_variable" /> section of the reference chapter.</para>
  </section>

  <section id="recipes_directories" xreflabel="directories">
    <title>Directories: What goes where</title>

    <para>A large part of the work of a recipe is involved with specifying
    where files are found and where they have to go. It's important for
    example that programs do not try and use files from <emphasis
    role="bold">/usr/include</emphasis> or <emphasis
    role="bold">/usr/lib</emphasis> since they are for the host system, not
    the target. Similarly you don't want programs installed into <emphasis
    role="bold">/usr/bin</emphasis> since that may overwrite your host system
    programs with versions that don't work on the host!</para>

    <para>The following are some of the directories commonly referred to in
    recipes and will be described in more detail in the rest of this
    section:</para>

    <variablelist>
      <varlistentry>
        <term>Working directory: WORKDIR</term>

        <listitem>
          <para>This working directory for a recipe is where archive files
          will be extracted, plain files will be placed, subdirectories for
          logs, installed files etc will be created.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Unpacked source code directory: S</term>

        <listitem>
          <para>This is where patches are applied and where the program is
          expected to be compiled.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Destination directory: D</term>

        <listitem>
          <para>The destination directory. This is where your package should
          be installed into. The packaging system will then take the files
          from directories under here and package them up for installation on
          the target.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Installation directories: bindir, docdir, ...</term>

        <listitem>
          <para>There are a set of variables available to describe all of the
          paths on the target that you may want to use. Recipes should use
          these variables rather than hard coding any specific paths.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Staging directories: STAGING_LIBDIR, STAGING_INCDIR, ...</term>

        <listitem>
          <para>Staging directories are a special area for headers, libraries
          and other files that are generated by one recipe that may be needed
          by another recipe. A library package for example needs to make the
          library and headers available to other recipes so that they can link
          against them.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>File path directories: FILE, FILE_DIRNAME, FILESDIR,
        FILESPATH</term>

        <listitem>
          <para>These directories are used to control where files are found.
          Understanding these can help you separate patches for different
          versions or releases of your recipes and/or use the same patch over
          multiple versions etc.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <section>
      <title>WORKDIR: The working directory</title>

      <para>The working directory is where the source code is extracted,
      plain files (not patches) are copied and where the logs and
      installation files are created. A typical reason for needing to
      reference the work directory is for the handling of non patch
      files.</para>

      <para>If we take a look at the recipe for quagga we can see example
      non patch files for configuration and init scripts:<screen>SRC_URI = "http://www.quagga.net/download/quagga-${PV}.tar.gz \
           file://fix-for-lib-inpath.patch \
           file://quagga.init \
           file://quagga.default \
           file://watchquagga.init \
           file://watchquagga.default"</screen>The recipe has two init files
      and two configuration files, which are not patches, but are actually
      files that it wants to include in the generated packages. Bitbake will
      copy these files into the working directory. So to access them during the
      install task we refer to them via the <emphasis
      role="bold">WORKDIR</emphasis> variable:<screen>do_install () {
    # Install init script and default settings
    install -m 0755 -d ${D}${sysconfdir}/default ${D}${sysconfdir}/init.d ${D}${sysconfdir}/quagga
    install -m 0644 ${WORKDIR}/quagga.default ${D}${sysconfdir}/default/quagga
    install -m 0644 ${WORKDIR}/watchquagga.default ${D}${sysconfdir}/default/watchquagga
    install -m 0755 ${WORKDIR}/quagga.init ${D}${sysconfdir}/init.d/quagga
    install -m 0755 ${WORKDIR}/watchquagga.init ${D}${sysconfdir}/init.d/watchquagga
    ...</screen></para>
    </section>

    <section>
      <title>S: The unpacked source code directory</title>

      <para>Bitbake expects to find the extracted source for a package in a
      directory called <emphasis
      role="bold">&lt;packagename&gt;-&lt;version&gt;</emphasis> in the
      <emphasis role="bold">WORKDIR</emphasis> directory. This is the
      directory it will change into before patching, compiling and
      installing the package.</para>

      <para>For example, we have a package called <emphasis
      role="bold">widgets_1.2.bb</emphasis> which we are extracting from the
      <emphasis role="bold">widgets-1.2.tar.gz</emphasis> file. Bitbake
      expects the source to end up in a directory called <emphasis
      role="bold">widgets-1.2</emphasis> within the work directory. If the
      source does not end up in this directory then bitbake needs to be told
      this by explicitly setting <emphasis role="bold">S</emphasis>.</para>

      <para>If <emphasis role="bold">widgets-1.2.tar.gz</emphasis> actually
      extracts into a directory called <emphasis
      role="bold">widgets</emphasis>, without the version number, instead of
      <emphasis role="bold">widgets-1.2</emphasis> then the <emphasis
      role="bold">S</emphasis> variable will be wrong and patching and/or
      compiling will fail. Therefore we need to override the default value of
      <emphasis role="bold">S</emphasis> to specify the directory the source
      was actually extracted into:<screen>SRC_URI = "http://www.example.com/software/widgets-${PN}.tar.gz"
S = "${WORKDIR}/widgets"</screen></para>
    </section>

    <section>
      <title>D: The destination directory</title>

      <para>The destination directory is where the completed application and
      all of its files are installed into in preparation for packaging.
      Typically an installation would place files in directories such as
      <emphasis role="bold">/etc</emphasis> and <emphasis
      role="bold">/usr/bin</emphasis> by default. Since those directories are
      used by the host system we do not want the packages to install into
      those locations. Instead they need to install into the directories below
      the destination directory.</para>

      <para>So instead of installing into <emphasis
      role="bold">/usr/bin</emphasis> the package needs to install into
      <emphasis role="bold">${D}/usr/bin</emphasis>.</para>

      <para>The following example from arpwatch shows the make install command
      being passed a <emphasis role="bold">${D}</emphasis> as the <emphasis
      role="bold">DESTDIR</emphasis> variable to control where the makefile
      installs everything:<screen>do_install() {
        ...
        oe_runmake install DESTDIR=${D}</screen></para>

      <para>The following example from quagga shows the use of the destination
      directory to install the configuration files and init scripts for the
      package:<screen>do_install () {
        # Install init script and default settings
        install -m 0755 -d ${D}${sysconfdir}/default ${D}${sysconfdir}/init.d ${D}${sysconfdir}/quagga
        install -m 0644 ${WORKDIR}/quagga.default ${D}${sysconfdir}/default/quagga
        install -m 0755 ${WORKDIR}/quagga.init ${D}${sysconfdir}/init.d/quagga</screen><note>
          <para>You should not use directories such as <emphasis
          role="bold">/etc</emphasis> and <emphasis
          role="bold">/usr/bin</emphasis> directly in your recipes. You should
          use the variables that define these locations. The full list of
          these variables can be found in the <xref
          linkend="directories_installation" /> section of the reference
          chapter.</para>
        </note></para>
    </section>

    <section>
      <title>Staging directories</title>

      <para>Staging is used to make libraries, headers and binaries available
      from the build of one recipe for use by another recipe. Building a
      library for example requires that packages be created containing the
      libraries and headers for development on the target as well as making
      them available on the host for building other packages that need the
      libraries and headers.</para>

      <para>Making the libraries, headers and binaries available for use by
      other recipes on the host is called staging and is performed by the
      <emphasis>stage</emphasis> task in the recipe. Any recipes that contain
      items that are required to build other packages should have a
      <emphasis>stage</emphasis> task to make sure the items are all correctly
      placed into the staging area. The following example from clamav shows the
      clamav library and header being placed into the staging area:<screen>do_stage () {
        oe_libinstall -a -so libclamav ${STAGING_LIBDIR}
        install -m 0644 libclamav/clamav.h ${STAGING_INCDIR}
}</screen></para>

      <para>The following from the p3scan recipe shows the path to the clamav
      library and header being passed to the configure script. Without this
      the configure script would either fail to find the library, or worse
      still search the host system's directories for the library. Passing in
      the location results in it searching the correct location and finding
      the clamav library and headers:<screen>EXTRA_OECONF = "--with-clamav=${STAGING_LIBDIR}/.. \
                --with-openssl=${STAGING_LIBDIR}/.. \
                --disable-ripmime"</screen>While the staging directories are
      automatically added by OpenEmbedded to the compiler and linking commands
      it is sometimes necessary, as in the p3scan example above, to explicitly
      specify the location of the staging directories. Typically this is
      needed for autoconf scripts that search in multiple places for the
      libraries and headers.</para>

      <note>
        <para>Many of the helper classes, such as pkgconfig and autotools add
        appropriate commands to the stage task for you. Check with the
        individual class descriptions in the reference section to determine
        what each class is staging automatically for you.</para>
      </note>

      <para>A full list of staging directories can be found in the <xref
      linkend="directories_staging" /> section in the reference
      chapter.</para>
    </section>

    <section id="recipes_filespath_dir" xreflabel="FILESPATH/FILESDIR">
      <title>FILESPATH/FILESDIR: Finding local files</title>

      <para>The file related variables are used by bitbake to determine where
      to look for patches and local files.</para>

      <para>Typically you will not need to modify these, but it is useful to
      be aware of the default values. In particular when searching for patches
      and/or files (file:// URIs), the default search path is:</para>

      <variablelist>
        <varlistentry>
          <term>${FILE_DIRNAME}/${PF}</term>

          <listitem>
            <para>This is the package name, version and release, such as
            "<emphasis role="bold">strace-4.5.14-r1</emphasis>". This is very
            rarely used since the patches would only be found for the one
            exact release of the recipe.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>${FILE_DIRNAME}/${P}</term>

          <listitem>
            <para>This is the package name and version, such as "<emphasis
            role="bold">strace-4.5.14</emphasis>". This is by far the most
            common place to place version specific patches.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>${FILE_DIRNAME}/${PN}</term>

          <listitem>
            <para>This is the package name only, such as "<emphasis
            role="bold">strace</emphasis>". This is not commonly used.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>${FILE_DIRNAME}/files</term>

          <listitem>
            <para>This is just the directory called "<emphasis
            role="bold">files</emphasis>". This is commonly used for patches
            and files that apply to all versions of the package.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>${FILE_DIRNAME}/</term>

          <listitem>
            <para>This is just the base directory of the recipe. This is very
            rarely used since it would just clutter the main directory.</para>
          </listitem>
        </varlistentry>
      </variablelist>

      <para>Each of the paths is relative to <emphasis
      role="bold">${FILE_DIRNAME}</emphasis> which is the directory in which
      the recipe that is being processed is located.</para>

      <para>The full set of variables that control the file locations
      are:</para>

      <variablelist>
        <varlistentry>
          <term>FILE</term>

          <listitem>
            <para>The path to the .bb file which is currently being
            processed.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>FILE_DIRNAME</term>

          <listitem>
            <para>The path to the directory which contains the FILE which is
            currently being processed.<screen>FILE_DIRNAME = "${@os.path.dirname(bb.data.getVar('FILE', d))}"</screen></para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>FILESPATH</term>

          <listitem>
            <para>The default set of directories which are available to use
            for the file:// URIs. Each directory is searched, in the
            specified order, in an attempt to find the file specified by each
            file:// URI: <screen>FILESPATH = "${FILE_DIRNAME}/${PF}:${FILE_DIRNAME}/${P}:\
${FILE_DIRNAME}/${PN}:${FILE_DIRNAME}/files:${FILE_DIRNAME}"</screen></para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>FILESDIR</term>

          <listitem>
            <para>The default directory to search for file:// URIs. Only used
            if the file is not found in FILESPATH. This can be used to easily
            add one additional directory to the search path without having to
            modify the default FILESPATH setting. By default this is just the
            first directory from FILESPATH. <screen>FILESDIR = "${@bb.which(bb.data.getVar('FILESPATH', d, 1), '.')}" </screen></para>
          </listitem>
        </varlistentry>
      </variablelist>

      <para>Sometimes recipes will modify the <emphasis
      role="bold">FILESPATH</emphasis> or <emphasis
      role="bold">FILESDIR</emphasis> variables to change the default search
      path for patches and files. The most common situation in which this is
      done is when one recipe includes another one in which the default values
      will be based on the name of the package doing the including, not the
      included package. Typically the included package will expect the files
      to be located in a directory based on its own name.</para>

      <para>As an example the m4-native recipe includes the m4 recipe. This is
      fine, except that the m4 recipe expects its files and patches to be
      located in a directory called <emphasis role="bold">m4</emphasis>,
      while the native file name results in them being searched for
      in <emphasis role="bold">m4-native</emphasis>. So the m4-native recipe
      sets the <emphasis role="bold">FILESDIR</emphasis> variable to the value
      of the actual m4 directory (where m4 itself has its files
      stored):<screen>        include m4_${PV}.bb
        inherit native
        FILESDIR = "${@os.path.dirname(bb.data.getVar('FILE',d,1))}/m4"</screen></para>
    </section>
  </section>

  <section id="recipes_examples" xreflabel="examples">
    <title>Basic examples</title>

    <para>By now you should know enough about the bitbake recipes to be able
    to create a basic recipe. We'll cover a simple single file recipe and then
    a more advanced example that uses the autotools helper class (to be
    described later) to build an autoconf based package.</para>

    <section id="recipes_helloworld_example" xreflabel="hello world example">
      <title>Hello world</title>

      <para>Now it's time for our first recipe. This is going to be one of the
      simplest possible recipes: all code is included and there's only one
      file to compile and one readme file. While this isn't all that common,
      it's a useful example because it doesn't depend on any of the helper
      classes which can sometime hide a lot of what is going on.</para>

      <para>First we'll create the myhelloworld.c file and a readme file.
      We'll place this in the files subdirectory, which is one of the places
      that is searched for file:// URIs:<screen>$ <command>mkdir</command> recipes/myhelloworld
$ <command>mkdir</command> recipes/myhelloworld/files
$ <command>cat</command> &gt; recipes/myhelloworld/files/myhelloworld.c
#include &lt;stdio.h&gt;

int main(int argc, char** argv)
{
        printf("Hello world!\n");
        return 0;
}
^D
$ <command>cat</command> &gt; recipes/myhelloworld/files/README.txt
Readme file for myhelloworld.
^D</screen></para>

      <para>Now we have a directory for our recipe, recipes/myhelloworld, and
      we've created a files subdirectory in there to store our local files.
      We've created two local files, the C source code for our helloworld
      program and a readme file. Now we need to create the bitbake
      recipe.</para>

      <para>First we need the header section, which will contain a description
      of the package and the release number. We'll leave the other header
      variables out for now:<screen>DESCRIPTION = "My hello world program"
PR = "r0"</screen></para>

      <para>Next we need to tell it which files we want to be included in the
      recipe, which we do via file:// URIs and the SRC_URI variable:<screen>SRC_URI = "file://myhelloworld.c \
           file://README.txt"</screen></para>

      <para>Note the use of the \ to continue a file and the use of file://
      local URIs, rather than other types such as http://.</para>

      <para>Now we need to provide a compile task which tells bitbake how to
      compile this program. We do this by defining a do_compile function in
      the recipe and providing the appropriate commands:</para>

      <para><screen>do_compile() {
        ${CC} ${CFLAGS} ${LDFLAGS} ${WORKDIR}/myhelloworld.c -o myhelloworld
}</screen></para>

      <para>Note the:</para>

      <itemizedlist>
        <listitem>
          <para>use of the pre-defined compiler variables, <emphasis
          role="bold">${CC}</emphasis>, <emphasis
          role="bold">${CFLAGS}</emphasis> and <emphasis
          role="bold">${LDFLAGS}</emphasis>. These are set up automatically to
          contain the settings required to cross-compile the program for the
          target.</para>
        </listitem>

        <listitem>
          <para>use of <emphasis role="bold">${WORKDIR}</emphasis> to find the
          source file. As mentioned previously all files are copied into the
          working directory and can be referenced via the <emphasis
          role="bold">${WORKDIR}</emphasis> variable.</para>
        </listitem>
      </itemizedlist>

      <para>And finally we want to install the program and readme file into
      the destination directory so that it'll be packaged up correctly. This
      is done via the install task, so we need to define a do_install function
      in the recipe to describe how to install the package:<screen>do_install() {
        install -m 0755 -d ${D}${bindir} ${D}${docdir}/myhelloworld
        install -m 0755 ${S}/myhelloworld ${D}${bindir}
        install -m 0644 ${WORKDIR}/README.txt ${D}${docdir}/myhelloworld
}</screen></para>

      <para>Note the:</para>

      <itemizedlist>
        <listitem>
          <para>use of the <emphasis role="bold">install</emphasis> command to
          create directories and install the files, not cp.</para>
        </listitem>

        <listitem>
          <para>way directories are created before we attempt to install any
          files into them. The install command takes care of any
          subdirectories that are missing, so we only need to create the full
          path to the directory - no need to create the subdirectories.</para>
        </listitem>

        <listitem>
          <para>way we install everything into the destination directory via
          the use of the <emphasis role="bold">${D}
          </emphasis>variable.</para>
        </listitem>

        <listitem>
          <para>way we use variables to refer to the target directories, such
          as <emphasis role="bold">${bindir}</emphasis> and <emphasis
          role="bold">${docdir}</emphasis>.</para>
        </listitem>

        <listitem>
          <para>use of <emphasis role="bold">${WORKDIR}</emphasis> to get
          access to the <emphasis role="bold">README.txt</emphasis> file,
          which was provided via a file:// URI.</para>
        </listitem>
      </itemizedlist>

      <para>We'll consider this release 0 and version 0.1 of a program called
      helloworld. So we'll name the recipe myhelloworld_0.1.bb:<screen>$ <command>cat</command> &gt; recipes/myhelloworld/myhelloworld_0.1.bb
DESCRIPTION = "Hello world program"
PR = "r0"

SRC_URI = "file://myhelloworld.c \
           file://README.txt"

do_compile() {
        ${CC} ${CFLAGS} ${LDFLAGS} ${WORKDIR}/myhelloworld.c -o myhelloworld
}

do_install() {
        install -m 0755 -d ${D}${bindir} ${D}${docdir}/myhelloworld
        install -m 0644 ${S}/myhelloworld ${D}${bindir}
        install -m 0644 ${WORKDIR}/README.txt ${D}${docdir}/myhelloworld
}
^D</screen>Now we are ready to build our package, hopefully it'll all work
      since it's such a simple example:<screen>$ <command>bitbake</command> -b recipes/myhelloworld/myhelloworld_0.1.bb
NOTE: package myhelloworld-0.1: started
NOTE: package myhelloworld-0.1-r0: task do_fetch: started
NOTE: package myhelloworld-0.1-r0: task do_fetch: completed
NOTE: package myhelloworld-0.1-r0: task do_unpack: started
NOTE: Unpacking /home/lenehan/devel/oe/local-recipes/myhelloworld/files/helloworld.c to /home/lenehan/devel/oe/build/titan-glibc-25/tmp/work/myhelloworld-0.1-r0/
NOTE: Unpacking /home/lenehan/devel/oe/local-recipes/myhelloworld/files/README.txt to /home/lenehan/devel/oe/build/titan-glibc-25/tmp/work/myhelloworld-0.1-r0/
NOTE: package myhelloworld-0.1-r0: task do_unpack: completed
NOTE: package myhelloworld-0.1-r0: task do_patch: started
NOTE: package myhelloworld-0.1-r0: task do_patch: completed
NOTE: package myhelloworld-0.1-r0: task do_configure: started
NOTE: package myhelloworld-0.1-r0: task do_configure: completed
NOTE: package myhelloworld-0.1-r0: task do_compile: started
NOTE: package myhelloworld-0.1-r0: task do_compile: completed
NOTE: package myhelloworld-0.1-r0: task do_install: started
NOTE: package myhelloworld-0.1-r0: task do_install: completed
NOTE: package myhelloworld-0.1-r0: task do_package: started
NOTE: package myhelloworld-0.1-r0: task do_package: completed
NOTE: package myhelloworld-0.1-r0: task do_package_write: started
NOTE: Not creating empty archive for myhelloworld-dbg-0.1-r0
Packaged contents of myhelloworld into /home/lenehan/devel/oe/build/titan-glibc-25/tmp/deploy/ipk/sh4/myhelloworld_0.1-r0_sh4.ipk
Packaged contents of myhelloworld-doc into /home/lenehan/devel/oe/build/titan-glibc-25/tmp/deploy/ipk/sh4/myhelloworld-doc_0.1-r0_sh4.ipk
NOTE: Not creating empty archive for myhelloworld-dev-0.1-r0
NOTE: Not creating empty archive for myhelloworld-locale-0.1-r0
NOTE: package myhelloworld-0.1-r0: task do_package_write: completed
NOTE: package myhelloworld-0.1-r0: task do_populate_sysroot: started
NOTE: package myhelloworld-0.1-r0: task do_populate_sysroot: completed
NOTE: package myhelloworld-0.1-r0: task do_build: started
NOTE: package myhelloworld-0.1-r0: task do_build: completed
NOTE: package myhelloworld-0.1: completed
Build statistics:
  Attempted builds: 1
$</screen></para>

      <para>The package was successfully built, the output consists of two
      .ipkg files, which are ready to be installed on the target. One contains
      the binary and the other contains the readme file:<screen>$ <command>ls</command> -l tmp/deploy/ipk/*/myhelloworld*
-rw-r--r--  1 lenehan lenehan 3040 Jan 12 14:46 tmp/deploy/ipk/sh4/myhelloworld_0.1-r0_sh4.ipk
-rw-r--r--  1 lenehan lenehan  768 Jan 12 14:46 tmp/deploy/ipk/sh4/myhelloworld-doc_0.1-r0_sh4.ipk
$</screen></para>

      <para>It's worthwhile looking at the working directory to see where
      various files ended up:<screen>$ <command>find</command> tmp/work/myhelloworld-0.1-r0
tmp/work/myhelloworld-0.1-r0
tmp/work/myhelloworld-0.1-r0/myhelloworld-0.1
tmp/work/myhelloworld-0.1-r0/myhelloworld-0.1/patches
tmp/work/myhelloworld-0.1-r0/myhelloworld-0.1/myhelloworld
tmp/work/myhelloworld-0.1-r0/temp
tmp/work/myhelloworld-0.1-r0/temp/run.do_configure.21840
tmp/work/myhelloworld-0.1-r0/temp/log.do_stage.21840
tmp/work/myhelloworld-0.1-r0/temp/log.do_install.21840
tmp/work/myhelloworld-0.1-r0/temp/log.do_compile.21840
tmp/work/myhelloworld-0.1-r0/temp/run.do_stage.21840
tmp/work/myhelloworld-0.1-r0/temp/log.do_configure.21840
tmp/work/myhelloworld-0.1-r0/temp/run.do_install.21840
tmp/work/myhelloworld-0.1-r0/temp/run.do_compile.21840
tmp/work/myhelloworld-0.1-r0/install
tmp/work/myhelloworld-0.1-r0/install/myhelloworld-locale
tmp/work/myhelloworld-0.1-r0/install/myhelloworld-dbg
tmp/work/myhelloworld-0.1-r0/install/myhelloworld-dev
tmp/work/myhelloworld-0.1-r0/install/myhelloworld-doc
tmp/work/myhelloworld-0.1-r0/install/myhelloworld-doc/usr
tmp/work/myhelloworld-0.1-r0/install/myhelloworld-doc/usr/share
tmp/work/myhelloworld-0.1-r0/install/myhelloworld-doc/usr/share/doc
tmp/work/myhelloworld-0.1-r0/install/myhelloworld-doc/usr/share/doc/myhelloworld
tmp/work/myhelloworld-0.1-r0/install/myhelloworld-doc/usr/share/doc/myhelloworld/README.txt
tmp/work/myhelloworld-0.1-r0/install/myhelloworld
tmp/work/myhelloworld-0.1-r0/install/myhelloworld/usr
tmp/work/myhelloworld-0.1-r0/install/myhelloworld/usr/bin
tmp/work/myhelloworld-0.1-r0/install/myhelloworld/usr/bin/myhelloworld
tmp/work/myhelloworld-0.1-r0/image
tmp/work/myhelloworld-0.1-r0/image/usr
tmp/work/myhelloworld-0.1-r0/image/usr/bin
tmp/work/myhelloworld-0.1-r0/image/usr/share
tmp/work/myhelloworld-0.1-r0/image/usr/share/doc
tmp/work/myhelloworld-0.1-r0/image/usr/share/doc/myhelloworld
tmp/work/myhelloworld-0.1-r0/myhelloworld.c
tmp/work/myhelloworld-0.1-r0/README.txt
$</screen>Things to note here are:</para>

      <itemizedlist>
        <listitem>
          <para>The two source files are in <emphasis
          role="bold">tmp/work/myhelloworld-0.1-r0</emphasis>, which is the
          working directory as specified via the <emphasis
          role="bold">${WORKDIR}</emphasis> variable;</para>
        </listitem>

        <listitem>
          <para>There's logs of the various tasks in <emphasis
          role="bold">tmp/work/myhelloworld-0.1-r0/temp</emphasis> which you
          can look at for more details on what was done in each task;</para>
        </listitem>

        <listitem>
          <para>There's an image directory at <emphasis
          role="bold">tmp/work/myhelloworld-0.1-r0/image</emphasis> which
          contains just the directories that were to be packaged up. This is
          actually the destination directory, as specified via the <emphasis
          role="bold">${D}</emphasis> variable. The two files that we
          installed were originally in here, but during packaging they were
          moved into the install area into a subdirectory specific to the
          package that was being created (remember we have a main package and
          a -doc package being created.</para>
        </listitem>

        <listitem>
          <para>The program was actually compiled in the <emphasis
          role="bold">tmp/work/myhelloworld-0.1-r0/myhelloworld-0.1</emphasis>
          directory, this is the source directory as specified via the
          <emphasis role="bold">${S}</emphasis> variable.</para>
        </listitem>

        <listitem>
          <para>There's an install directory at <emphasis
          role="bold">tmp/work/myhelloworld-0.1-r0/install</emphasis> which
          contains the packages that were being generated and the files that
          go in the package. So we can see that the myhelloworld-doc package
          contains the single file <emphasis
          role="bold">/usr/share/doc/myhelloworld/README.txt</emphasis>, the
          myhelloworld package contains the single file <emphasis
          role="bold">/usr/bin/myhelloworld</emphasis> and the -dev, -dbg and
          -local packages are all empty.</para>
        </listitem>
      </itemizedlist>

      <para>At this stage it's good to verify that we really did produce a
      binary for the target and not for our host system. We can check that
      with the file command:<screen>$ <command>file</command> tmp/work/myhelloworld-0.1-r0/install/myhelloworld/usr/bin/myhelloworld
tmp/work/myhelloworld-0.1-r0/install/myhelloworld/usr/bin/myhelloworld: ELF 32-bit LSB executable, Hitachi SH, version 1 (SYSV), for GNU/Linux 2.4.0, dynamically linked (uses shared libs), for GNU/Linux 2.4.0, not stripped
$ <command>file</command> /bin/ls
/bin/ls: ELF 64-bit LSB executable, AMD x86-64, version 1 (SYSV), for GNU/Linux 2.4.0, dynamically linked (uses shared libs), for GNU/Linux 2.4.0, stripped
$</screen>This shows us that the helloworld program is for an SH
      processor (obviously this will change depending on what your target
      system is), while checking the <emphasis role="bold">/bin/ls</emphasis>
      program on the host shows us that the host system is an AMD X86-64 system.
      That's exactly what we wanted.</para>
    </section>

    <section id="recipes_autoconf_example" xreflabel="autoconf example">
      <title>An autotools package</title>

      <para>Now for an example of a package that uses autotools. These are
      programs that you need to run a configure script for, passing various
      parameters, and then make. To make these work when cross-compiling you
      need to provides a lot of variables to the configure script. But all the
      hard work has already been done for you. There's an <xref
      linkend="autotools_class" /> which takes care of most of the complexity
      of building an autotools based package.</para>

      <para>Let's take a look at the tuxnes recipe which is an example of a
      very simple autotools based recipe:<screen>$ <command>cat</command> recipes/tuxnes/tuxnes_0.75.bb
DESCRIPTION = "Tuxnes Nintendo (8bit) Emulator"
HOMEPAGE = "http://prdownloads.sourceforge.net/tuxnes/tuxnes-0.75.tar.gz"
LICENSE = "GPLv2"
SECTION = "x/games"
PRIORITY = "optional"
PR = "r1"

SRC_URI = "http://heanet.dl.sourceforge.net/sourceforge/tuxnes/tuxnes-0.75.tar.gz"

inherit autotools</screen></para>

      <para>This is a really simple recipe. There's the standard header that
      describes the package. Then the SRC_URI, which in this case is an http
      URL that causes the source code to be downloaded from the specified URI.
      And finally there's an "<emphasis role="bold">inherit
      autotools</emphasis>" command which loads the autotools class. The
      autotools class will take care of generating the required configure,
      compile and install tasks. So in this case there's nothing else to do -
      that's all there is to it.</para>

      <para>It would be nice if it was always this simple. Unfortunately
      there's usually a lot more involved for various reasons including the
      need to:</para>

      <itemizedlist>
        <listitem>
          <para>Pass parameters to configure to enable and disable
          features;</para>
        </listitem>

        <listitem>
          <para>Pass parameters to configure to specify where to find
          libraries and headers;</para>
        </listitem>

        <listitem>
          <para>Make modifications to prevent searching for headers and
          libraries in the normal locations (since they belong to the host
          system, not the target);</para>
        </listitem>

        <listitem>
          <para>Make modifications to prevent the configure script from trying
          to compile and run programs - any programs it compiles will be for
          the target and not the host and so cannot be run.</para>
        </listitem>

        <listitem>
          <para>Manually implement staging scripts;</para>
        </listitem>

        <listitem>
          <para>Deal with lots of other more complex issues;</para>
        </listitem>
      </itemizedlist>

      <para>Some of these items are covered in more detail in the advanced
      autoconf section.</para>
    </section>
  </section>

  <section id="recipes_dependencies" xreflabel="dependencies">
    <title>Dependencies: What's needed to build and/or run the
    package?</title>

    <para>Dependencies should be familiar to anyone who has used an .rpm and
    .deb based desktop distribution. A dependency is something that a package
    requires either to run the package (a run-time dependency) or to build the
    package (a build-time or compile-time, dependency).</para>

    <para>There are two variables provided to allow the specifications of
    dependencies:</para>

    <variablelist>
      <varlistentry>
        <term>DEPENDS</term>

        <listitem>
          <para>Specifies build-time dependencies, via a list of bitbake
          recipes to build prior to building the recipe. These are programs
          (flex-native) or libraries (libpcre) that are required in order to
          build the package.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>RDEPENDS</term>

        <listitem>
          <para>Specifies run-time dependencies, via a list of packages to
          install prior to installing the current package. These are programs
          or libraries that are required in order to run the program. Note
          that libraries which are dynamically linked to an application will
          be automatically detected and added to <emphasis
          role="bold">RDEPENDS</emphasis> and therefore do not need to be
          explicitly declared. If a library was dynamically loaded then it
          would need to be explicitly listed.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>If we take openssh for an example, it requires zlib and openssl in
    order to both build and run. In the recipe we have:<screen>DEPENDS = "zlib openssl"</screen>This
    tells bitbake that it will need to build and stage zlib and openssl prior
    to trying to build openssh, since openssh requires both of them. Note that
    there is no <emphasis role="bold">RDEPENDS</emphasis> even though openssh
    requires both of them to run. The run time dependencies on libz1 (the name
    of the package containing the zlib library) and libssl0 (the name of the
    package containing the ssl library) are automatically determined and added
    via the auto shared libs dependency code.</para>
  </section>

  <section id="recipes_methods" xreflabel="methods">
    <title>Methods: Built-in methods to make your life easier</title>

    <para>There are several helper functions defined by the base class, which
    is included by default for all recipes. Many of these are used a lot in
    both recipes and other classes.</para>

    <para>The most commonly seen, and most useful functions, include:</para>

    <variablelist>
      <varlistentry>
        <term>oe_runmake</term>

        <listitem>
          <para>This function is used to run make. However unlike calling make
          yourself this will pass the EXTRA_OEMAKE settings to make, will
          display a note about the make command and will check for any errors
          generated via the call to make.</para>

          <para>You should never have any reason to call make directly and
          should also use oe_runmake when you need to run make.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>oe_runconf (autotools only)</term>

        <listitem>
          <para>This function is used to run the configure script of a package
          that is using the autotools class. This takes care of passing all of
          the correct parameters for cross-compiling and for installing into
          the appropriate target directory.</para>

          <para>It also passes the value of the <emphasis
          role="bold">EXTRA_OECONF</emphasis> variable to the configure
          script. For many situations setting <emphasis
          role="bold">EXTRA_OECONF</emphasis> is sufficient and you'll have no
          need to define your own configure task in which you call oe_runconf
          manually.</para>

          <para>If you need to write your own <emphasis>configure</emphasis>
          task for an autotools package you can use oe_runconf to manually
          call the configure process when it is required. The following
          example from net-snmp shows oe_runconf being called manually so that
          the parameter for specifying the endianess can be computed and
          passed in to the configure script:<screen>do_configure() {
    # Additional flag based on target endianess (see siteinfo.bbclass)
    ENDIANESS="${@base_conditional('SITEINFO_ENDIANNESS', 'le', '--with-endianness=little', '--with-endianness=big', d)}"
    oenote Determined endianess as: $ENDIANESS
    oe_runconf $ENDIANESS
}</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>oe_libinstall</term>

        <listitem>
          <para>This function is used to install <emphasis
          role="bold">.so</emphasis>, <emphasis role="bold">.a</emphasis> and
          associated libtool <emphasis role="bold">.la</emphasis> libraries.
          It will determine the appropriate libraries to install and take care
          of any modifications that may be required for <emphasis
          role="bold">.la</emphasis> files.</para>

          <para>This function supports the following options:</para>

          <variablelist>
            <varlistentry>
              <term>-C &lt;dir&gt;</term>

              <listitem>
                <para>Change into the specified directory before attempting to
                install a library. Used when the libraries are in
                subdirectories of the main package.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>-s</term>

              <listitem>
                <para>Require the presence of a <emphasis
                role="bold">.so</emphasis> library as one of the libraries
                that is installed.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>-a</term>

              <listitem>
                <para>Require the presence of a <emphasis
                role="bold">.a</emphasis> library as one of the libraries that
                is installed.</para>
              </listitem>
            </varlistentry>
          </variablelist>

          <para>The following example from gdbm shows the installation of
          <emphasis role="bold">.so</emphasis>, <emphasis
          role="bold">.a</emphasis> (and associated <emphasis
          role="bold">.la</emphasis>) libraries into the staging library
          area:<screen>do_stage () {
    oe_libinstall -so -a libgdbm ${STAGING_LIBDIR}
    install -m 0644 ${S}/gdbm.h ${STAGING_INCDIR}/
}</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>oenote</term>

        <listitem>
          <para>Used to display informational messages to the user.</para>

          <para>The following example from net-snmp uses oenote to tell the
          user which endianess it determined was appropriate for the target
          device:<screen>do_configure() {
    # Additional flag based on target endianess (see siteinfo.bbclass)
    ENDIANESS="${@base_conditional('SITEINFO_ENDIANNESS', 'le', '--with-endianness=little', '--with-endianness=big', d)}"
    oenote Determined endianess as: $ENDIANESS
    oe_runconf $ENDIANESS
}</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>oewarn</term>

        <listitem>
          <para>Used to display a warning message to the user, warning of
          something that may be problematic or unexpected.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>oedebug</term>

        <listitem>
          <para>Used to display debugging related information. These messages
          will only be visible when bitbake is run with the <emphasis
          role="bold">-D</emphasis> flag to enable debug output.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>oefatal</term>

        <listitem>
          <para>Used to display a fatal error message to the user, and then
          abort the bitbake run.</para>

          <para>The following example from linux-libc-headers shows the use of
          oefatal to tell the user when it cannot find the kernel source code
          for the specified target architecture:<screen>do_configure () {
    case ${TARGET_ARCH} in
        alpha*)   ARCH=alpha ;;
        arm*)     ARCH=arm ;;
        cris*)    ARCH=cris ;;
        hppa*)    ARCH=parisc ;;
        i*86*)    ARCH=i386 ;;
        ia64*)    ARCH=ia64 ;;
        mips*)    ARCH=mips ;;
        m68k*)    ARCH=m68k ;;
        powerpc*) ARCH=ppc ;;
        s390*)    ARCH=s390 ;;
        sh*)      ARCH=sh ;;
        sparc64*) ARCH=sparc64 ;;
        sparc*)   ARCH=sparc ;;
        x86_64*)  ARCH=x86_64 ;;
    esac
    if test !  -e include/asm-$ARCH; then
        oefatal unable to create asm symlink in kernel headers
    fi
...</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>base_conditional (python)</term>

        <listitem>
          <para>The base conditional python function is used to set a variable
          to one of two values based on the definition of a third variable.
          The general usage is:<screen>${@base_conditional('&lt;variable-name&gt;', '&lt;value&gt;', '&lt;true-result&gt;', '&lt;false-result&gt;', d)}"</screen>where:</para>

          <variablelist>
            <varlistentry>
              <term>variable-name</term>

              <listitem>
                <para>This is the name of a variable to check.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>value</term>

              <listitem>
                <para>This is the value to compare the variable
                against.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>true-result</term>

              <listitem>
                <para>If the variable equals the value then this is what is
                returned by the function.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>false-result</term>

              <listitem>
                <para>If the variable does not equal the value then this is
                what is returned by the function.</para>
              </listitem>
            </varlistentry>
          </variablelist>

          <note>
            <para>The ${@...} syntax is used to call python functions from
            within a recipe or class. This is described in more detail in the
            <xref linkend="recipes_advanced_python" /> section.</para>
          </note>

          <para>The following example from the openssl recipe shows the
          addition of either <emphasis role="bold">-DL_ENDIAN</emphasis> or
          <emphasis role="bold">-DB_ENDIAN</emphasis> depending on the value
          of <emphasis role="bold">SITEINFO_ENDIANNESS</emphasis> which is set
          to le for little endian targets and to be for big endian
          targets:<screen>do_compile () {
    ...
    # Additional flag based on target endianess (see siteinfo.bbclass)
    CFLAG="${CFLAG} ${@base_conditional('SITEINFO_ENDIANNESS', 'le', '-DL_ENDIAN', '-DB_ENDIAN', d)}"
    ...</screen></para>
        </listitem>
      </varlistentry>
    </variablelist>
  </section>

  <section id="recipes_packages" xreflabel="packages">
    <title>Packaging: Defining packages and their contents</title>

    <para>A bitbake recipe is a set of instructions for creating one, or
    more, packages for installation on the target device. Typically these are
    .ipkg or .deb packages (although bitbake itself isn't associated with any
    particular packaging format).</para>

    <para>By default several packages are produced automatically without any
    special action required on the part of the recipe author. The following
    example of the packaging output from the helloworld example above shows
    this packaging in action:<screen>[NOTE: package helloworld-0.1-r0: task do_package_write: started
NOTE: Not creating empty archive for helloworld-dbg-0.1-r0
Packaged contents of helloworld into /home/lenehan/devel/oe/build/titan-glibc-25/tmp/deploy/ipk/sh4/helloworld_0.1-r0_sh4.ipk
Packaged contents of helloworld-doc into /home/lenehan/devel/oe/build/titan-glibc-25/tmp/deploy/ipk/sh4/helloworld-doc_0.1-r0_sh4.ipk
NOTE: Not creating empty archive for helloworld-dev-0.1-r0
NOTE: Not creating empty archive for helloworld-locale-0.1-r0
NOTE: package helloworld-0.1-r0: task do_package_write: completed</screen>We
    can see from above that the packaging did the following:</para>

    <itemizedlist>
      <listitem>
        <para>Created a main package, <emphasis
        role="bold">helloworld_0.1-r0_sh4.ipk</emphasis>. This package
        contains the helloworld binary <emphasis
        role="bold">/usr/bin/helloworld</emphasis>.</para>
      </listitem>

      <listitem>
        <para>Created a documentation package, <emphasis
        role="bold">helloworld-doc_0.1-r0_sh4.ipk</emphasis>. This package
        contains the readme file <emphasis
        role="bold">/usr/share/doc/helloworld/README.txt</emphasis>.</para>
      </listitem>

      <listitem>
        <para>Considered creating a debug package, <emphasis
        role="bold">helloworld-dbg-0.1-r0_sh4.ipk</emphasis>, a development
        package <emphasis role="bold">helloworld-dev-0.1-r0_sh4.ipk</emphasis>
        and a locale package <emphasis
        role="bold">helloworld-locale-0.1-r0_sh4.ipk</emphasis>. It didn't
        create the packages due to the fact that it couldn't find any files
        that would actually go in the packages.</para>
      </listitem>
    </itemizedlist>

    <para>There are several things happening here which are important to
    understand:</para>

    <orderedlist>
      <listitem>
        <para>There is a default set of packages that are considered for
        creation. This set of packages is controlled via the <emphasis
        role="bold">PACKAGES</emphasis> variable.</para>
      </listitem>

      <listitem>
        <para>For each package there is a default set of files and/or
        directories that are considered to belong to those packages. The
        documentation packages for example include anything found <emphasis
        role="bold">/usr/share/doc</emphasis>. The set of files and
        directories are controlled via the <emphasis
        role="bold">FILES_&lt;package-name&gt;</emphasis> variables.</para>
      </listitem>

      <listitem>
        <para>By default packages that contain no files are not created and no
        error is generated. The decision to create empty packages or not is
        controlled via the <emphasis role="bold">ALLOW_EMPTY</emphasis>
        variable.</para>
      </listitem>
    </orderedlist>

    <section>
      <title>Philosophy</title>

      <para>Separate packaging, where possible, is of high importance in
      OpenEmbedded. Many of the target devices have limited storage space and
      RAM and giving distributions and users the option of not installing a
      part of the package they don't need allows them to reduce the amount of
      storage space required.</para>

      <para>As an example almost no distributions will include documentation
      or development libraries since they are not required for the day to day
      operation of the device. In particular if your package provides multiple
      binaries, and it would be common to only use one or the other, then you
      should consider separating them into separate packages.</para>

      <para>By default several groups of files are automatically separated out,
      including:</para>

      <variablelist>
        <varlistentry>
          <term>dev</term>

          <listitem>
            <para>Any files required for development. This includes header
            files, static libraries, the shared library symlinks required only
            for linking etc. These would only ever need to be installed by
            someone attempting to compile applications on the target device.
            While this does happen it is very uncommon and so these files are
            automatically moved into a separate package</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>doc</term>

          <listitem>
            <para>Any documentation related files, including man pages. These
            are files which are of informational purposes only. For many
            embedded devices there is no way for the user to see any of the
            documentation anyway, and documentation can consume a lot of
            space. By separating these out they don't take any space by
            default but distributions and/or users may choose to install them
            if they need some documentation on a specific package.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>locale</term>

          <listitem>
            <para>Locale information provides translation information for
            packages. Many users do not require these translations, and many
            devices will only want to provide them for user visible
            components, such as UI related items, and not for system binaries.
            By separating these out it is left up to the distribution or users
            to decide if they are required or not.</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </section>

    <section>
      <title>Default packages and files</title>

      <para>The default package settings are defined in <emphasis
      role="bold">conf/bitbake.conf</emphasis> and are suitable for a lot of
      recipes without any changes. The following list shows the default values
      for the packaging related variables:</para>

      <para><variablelist>
          <varlistentry>
            <term>PACKAGES</term>

            <listitem>
              <para>This variable lists the names of each of the packages that
              are to be generated.<screen>PACKAGES = "${PN}-dbg ${PN} ${PN}-doc ${PN}-dev ${PN}-locale"</screen>Note
              that the order of packages is important: the packages are
              processed in the listed order. So if two packages specify the
              same file then the first package listed in packages will get the
              file. This is important when packages use wildcards to specify
              their contents.</para>

              <para>For example if the main package, <emphasis
              role="bold">${PN}</emphasis>, contains <emphasis
              role="bold">/usr/bin/*</emphasis> (i.e. all files in <emphasis
              role="bold">/usr/bin</emphasis>), but you want <emphasis
              role="bold">/usr/bin/tprogram</emphasis> in a separate package,
              <emphasis role="bold">${PN}-tpackage</emphasis>, you would need
              to either ensure that <emphasis
              role="bold">${PN}-tpackage</emphasis> is listed prior to
              <emphasis role="bold">${PN}</emphasis> in <emphasis
              role="bold">PACKAGES</emphasis> or that <emphasis
              role="bold">FILES_${PN}</emphasis> was modified to not contain
              the wildcard that matches <emphasis
              role="bold">/usr/bin/tprogram</emphasis>.</para>

              <para>Note that the -dbg package contains the debugging
              information that has been extracted from binaries and libraries
              prior to them being stripped. This package should always be the
              first package in the package list to ensure that the debugging
              information is correctly extracted and moved to the package
              prior to any other packaging decisions being made.</para>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term>FILES_${PN}</term>

            <listitem>
              <para>The base package, this includes everything needed to
              actually run the application on the target system.<screen>FILES_${PN} = "\
    ${bindir}/* \
    ${sbindir}/* \
    ${libexecdir}/* \
    ${libdir}/lib*.so.* \
    ${sysconfdir} \
    ${sharedstatedir} \
    ${localstatedir} \
    /bin/* \
    /sbin/* \
    /lib/*.so* \
    ${datadir}/${PN} \
    ${libdir}/${PN}/* \
    ${datadir}/pixmaps \
    ${datadir}/applications \
    ${datadir}/idl \
    ${datadir}/omf \
    ${datadir}/sounds \
    ${libdir}/bonobo/servers"</screen></para>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term>FILES_${PN}-dbg</term>

            <listitem>
              <para>The debugging information extracted from non-stripped
              versions of libraries and executable's. OpenEmbedded
              automatically extracts the debugging information into files in
              .debug directories and then strips the original files.<screen>FILES_${PN}-dbg = "\
    ${bindir}/.debug \
    ${sbindir}/.debug \
    ${libexecdir}/.debug \
    ${libdir}/.debug \
    /bin/.debug \
    /sbin/.debug \
    /lib/.debug \
    ${libdir}/${PN}/.debug"</screen></para>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term>FILES_${PN}-doc</term>

            <listitem>
              <para>Documentation related files. All documentation is
              separated into its own package so that it does not need to be
              installed unless explicitly required.<screen>FILES_${PN}-doc = "\
    ${docdir} \
    ${mandir} \
    ${infodir} \
    ${datadir}/gtk-doc \
    ${datadir}/gnome/help"</screen></para>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term>FILES_${PN}-dev</term>

            <listitem>
              <para>Development related files. Any headers, libraries and
              support files needed for development work on the target.<screen>FILES_${PN}-dev = "\
    ${includedir} \
    ${libdir}/lib*.so \
    ${libdir}/*.la \
    ${libdir}/*.a \
    ${libdir}/*.o \
    ${libdir}/pkgconfig \
    /lib/*.a \
    /lib/*.o \
    ${datadir}/aclocal"</screen></para>
            </listitem>
          </varlistentry>

          <varlistentry>
            <term>FILES_${PN}-locale</term>

            <listitem>
              <para>Locale related files.<screen>FILES_${PN}-locale = "${datadir}/locale"</screen></para>
            </listitem>
          </varlistentry>
        </variablelist></para>
    </section>

    <section>
      <title>Wildcards</title>

      <para>Wildcards used in the <emphasis role="bold">FILES</emphasis>
      variables are processed via the python function <emphasis
      role="bold">fnmatch</emphasis>. The following items are of note about
      this function:</para>

      <itemizedlist>
        <listitem>
          <para><emphasis role="bold">/&lt;dir&gt;/*</emphasis>: This will
          match all files and directories in the <emphasis
          role="bold">dir</emphasis> - it will not match other
          directories.</para>
        </listitem>

        <listitem>
          <para><emphasis role="bold">/&lt;dir&gt;/a*</emphasis>: This will
          only match files, and not directories.</para>
        </listitem>

        <listitem>
          <para><emphasis role="bold">/dir</emphasis>: will include the
          directory <emphasis role="bold">dir</emphasis> in the package, which
          in turn will include all files in the directory and all
          subdirectories.</para>
        </listitem>
      </itemizedlist>

      <para>Note that the order of packages effects the files that will be
      matched via wildcards. Consider the case where we have three binaries in
      the <command>/usr/bin</command> directory and we want the test program
      in a separate package:<screen>/usr/bin/programa /usr/bin/programb /usr/bin/test</screen>So
      we define a new package and instruct bitbake to include /usr/bin/test in
      it.</para>

      <screen>FILES-${PN}-test = "${bindir}/test"
PACKAGES += "FILES-${PN}-test"</screen>

      <para>When the package is regenerated no <emphasis
      role="bold">${PN}-test</emphasis> package will be created. The reason
      for this is that the <emphasis role="bold">PACKAGES</emphasis> line now
      looks like this:<screen>{PN}-dbg ${PN} ${PN}-doc ${PN}-dev ${PN}-locale ${PN}-test</screen>Note
      how <emphasis role="bold">${PN}</emphasis> is listed prior to <emphasis
      role="bold">${PN}-test</emphasis>, and if we look at the definition of
      <emphasis role="bold">FILES-${PN}</emphasis> it contains the <emphasis
      role="bold">${bindir}/*</emphasis> wildcard. Since <emphasis
      role="bold">${PN}</emphasis> is first it'll match that wildcard and be
      moved into the <emphasis role="bold">${PN}</emphasis> package prior to
      processing of the <emphasis role="bold">${PN}-test</emphasis>
      package.</para>

      <para>To achieve what we are trying to accomplish we have two
      options:</para>

      <orderedlist>
        <listitem>
          <para>Modify the definition of <emphasis
          role="bold">${PN}</emphasis> so that the wildcard does not match the
          test program.</para>

          <para>We could do this for example:<screen>FILES-${PN} = "${bindir}/p*"</screen>So
          now this will only match things in the bindir that start with p, and
          therefore not match our test program. Note that <emphasis
          role="bold">FILES-${PN}</emphasis> contains a lot more entries and
          we'd need to add any of the others that refer to files that are to be
          included in the package. In this case we have no other files, so
          it's safe to do this simple declaration.</para>
        </listitem>

        <listitem>
          <para>Modify the order of packages so that the <emphasis
          role="bold">${PN}-test</emphasis> package is listed first.</para>

          <para>The most obvious way to do this would be to prepend our new
          package name to the packages list instead of appending it:<screen>PACKAGES =+ "FILES-${PN}-test"</screen>In
          some cases this would work fine, however there is a problem with
          this for packages that include binaries. The package will now be
          listed before the -dbg package and often this will result in the
          .debug directories being included in the package. In this case we
          are explicitly listing only a single file (and not using wildcards)
          and therefore it would be ok.</para>

          <para>In general it's more common to have to redefine the entire
          package list to include your new package plus any of the default
          packages that you require:<screen>PACKAGES = "${PN}-dbg ${PN}-test ${PN} ${PN}-doc ${PN}-dev ${PN}-locale"</screen></para>
        </listitem>
      </orderedlist>
    </section>

    <section>
      <title>Checking the packages</title>

      <para>During recipe development it's useful to be able to check on
      exactly what files went into each package, which files were not packaged
      and which packages contain no files.</para>

      <para>One of the easiest methods is to run find on the install directory. In
      the install directory there is one subdirectory created per package, and
      the files are moved into the install directory as they are matched to a
      specific package. The following shows the packages and files for the
      helloworld example:<screen>$ <command>find</command> tmp/work/helloworld-0.1-r0/install
tmp/work/helloworld-0.1-r0/install
tmp/work/helloworld-0.1-r0/install/helloworld-locale
tmp/work/helloworld-0.1-r0/install/helloworld-dbg
tmp/work/helloworld-0.1-r0/install/helloworld-dev
tmp/work/helloworld-0.1-r0/install/helloworld-doc
tmp/work/helloworld-0.1-r0/install/helloworld-doc/usr
tmp/work/helloworld-0.1-r0/install/helloworld-doc/usr/share
tmp/work/helloworld-0.1-r0/install/helloworld-doc/usr/share/doc
tmp/work/helloworld-0.1-r0/install/helloworld-doc/usr/share/doc/helloworld
tmp/work/helloworld-0.1-r0/install/helloworld-doc/usr/share/doc/helloworld/README.txt
tmp/work/helloworld-0.1-r0/install/helloworld
tmp/work/helloworld-0.1-r0/install/helloworld/usr
tmp/work/helloworld-0.1-r0/install/helloworld/usr/bin
tmp/work/helloworld-0.1-r0/install/helloworld/usr/bin/helloworld
$</screen>The above shows that the -local, -dbg and -dev packages are
      all empty, and the -doc and base package contain a single file each.
      Using the "<emphasis role="bold">-type f</emphasis>" option to find to show
      just files will make this clearer as well.</para>

      <para>In addition to the install directory the image directory (which
      corresponds to the destination directory, <emphasis
      role="bold">D</emphasis>) will contain any files that were not
      packaged:<screen>$ <command>find</command> tmp/work/helloworld-0.1-r0/image
tmp/work/helloworld-0.1-r0/image
tmp/work/helloworld-0.1-r0/image/usr
tmp/work/helloworld-0.1-r0/image/usr/bin
tmp/work/helloworld-0.1-r0/image/usr/share
tmp/work/helloworld-0.1-r0/image/usr/share/doc
tmp/work/helloworld-0.1-r0/image/usr/share/doc/helloworld
$</screen>In this case all files were packaged and so there are no
      left over files. Using find with "<emphasis role="bold">-type
      f</emphasis>" makes this much clearer:<screen>$ <command>find</command> tmp/work/helloworld-0.1-r0/image -type f
$</screen></para>

      <para>Messages regarding missing files are also displayed by bitbake during
      the package task:<screen>NOTE: package helloworld-0.1-r0: task do_package: started
NOTE: the following files were installed but not shipped in any package:
NOTE:   /usualdir/README.txt
NOTE: package helloworld-0.1-r0: task do_package: completed</screen>Except in
      very unusual circumstances there should be no unpackaged files left
      behind by a recipe.</para>
    </section>

    <section>
      <title>Excluding files</title>

      <para>There's no actual support for explicitly excluding files from
      packaging. You could just leave them out of any package, but then you'll
      get warnings (or errors if requesting full package checking) during
      packaging which is not desirable. It also doesn't let other people know
      that you've deliberately avoided packaging the file or files.</para>

      <para>In order to exclude a file totally you should avoid installing it
      in the first place during the install task.</para>

      <para>In some cases it may be easier to let the package install the file
      and then explicitly remove the file at the end of the install task. The
      following example from the samba recipe shows the removal of several
      files that get installed via the default install task generated by the
      <xref linkend="autotools_class" />. By using
      <emphasis>do_install_append</emphasis> these commands are run after the
      autotools generated install task:</para>

      <screen>do_install_append() {
    ...
    rm -f ${D}${bindir}/*.old
    rm -f ${D}${sbindir}/*.old
    ...
}</screen>
    </section>

    <section>
      <title>Debian naming</title>

      <para>A special <emphasis>debian library name</emphasis> policy can be
      applied for packages that contain a single shared library. When enabled
      packages will be renamed to match the debian policy for such
      packages.</para>

      <para>Debian naming is enabled by including the debian class via either
      <command>local.conf</command> or your distribution's configuration
      file:<screen>INHERIT += "debian"</screen></para>

      <para>The policy works by looking at the shared library name and version
      and will automatically rename the package to
      <emphasis>&lt;libname&gt;&lt;lib-major-version&gt;</emphasis>. For
      example if the package name (PN) is <command>foo</command> and the
      package ships a file named <command>libfoo.so.1.2.3</command> then the
      package will be renamed to <command>libfoo1</command> to follow the
      debian policy.</para>

      <para>If we look at the <emphasis>lzo_1.08.bb</emphasis> recipe,
      currently at release 14, it generates a package containing a single
      shared library :<screen>$ <command>find</command> tmp/work/lzo-1.08-r14/install/
tmp/work/lzo-1.08-r14/install/lzo
tmp/work/lzo-1.08-r14/install/lzo/usr
tmp/work/lzo-1.08-r14/install/lzo/usr/lib
tmp/work/lzo-1.08-r14/install/lzo/usr/lib/liblzo.so.1
tmp/work/lzo-1.08-r14/install/lzo/usr/lib/liblzo.so.1.0.0</screen>Without
      debian naming this package would have been called
      <command>lzo_1.08-r14_sh4.ipk</command> (and the corresponding dev and
      dbg packages would have been called
      <command>lzo-dbg_1.08-r14_sh4.ipk</command> and
      <command>lzo-dev_1.08-r14_sh4.ipk</command>). However with debian naming
      enabled the package is renamed based on the name of the shared library,
      which is <command>liblzo.so.1.0.0</command> in this case. So the name
      <command>lzo</command> is replaced with
      <command>liblzo1</command>:<screen>$ <command>find</command> tmp/deploy/ipk/ -name '*lzo*'  
tmp/deploy/ipk/sh4/liblzo1_1.08-r14_sh4.ipk
tmp/deploy/ipk/sh4/liblzo-dev_1.08-r14_sh4.ipk
tmp/deploy/ipk/sh4/liblzo-dbg_1.08-r14_sh4.ipk</screen></para>

      <para>Some variables are available which effect the operation of the
      debian renaming class:</para>

      <variablelist>
        <varlistentry>
          <term>LEAD_SONAME</term>

          <listitem>
            <para>If the package actually contains multiple shared libraries
            then one will be selected automatically and a warning will be
            generated. This variable is a regular expression which is used to
            select which shared library from those available is to be used for
            debian renaming.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>DEBIAN_NOAUTONAME_&lt;pkgname&gt;</term>

          <listitem>
            <para>If this variable is set to 1 for a package then debian
            renaming will not be applied for the package.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>AUTO_LIBNAME_PKGS</term>

          <listitem>
            <para>If set this variable specifies the prefix of packages which
            will be subject to debian renaming. This can be used to prevent
            all of the packages being renamed via the renaming policy.</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </section>

    <section>
      <title>Empty packages</title>

      <para>By default empty packages are ignored. Occasionally you may wish
      to actually create empty packages, typically done when you want a
      virtual package which will install other packages via dependencies
      without actually installing anything itself. The <emphasis
      role="bold">ALLOW_EMPTY</emphasis> variable is used to control the
      creation of empty packages:</para>

      <variablelist>
        <varlistentry>
          <term>ALLOW_EMPTY</term>

          <listitem>
            <para>Controls if empty packages will be created or not. By
            default this is <emphasis role="bold">"0"</emphasis> and empty
            packages are not created. Setting this to <emphasis
            role="bold">"1"</emphasis> will permit the creation of empty
            packages (packages containing no files).</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </section>
  </section>

  <section id="recipes_tasks" xreflabel="tasks">
    <title>Tasks: Playing with tasks</title>

    <para>Bitbake steps through a series of tasks when building a recipe.
    Sometimes you need to explicitly define what a class does, such as
    providing a <emphasis role="bold">do_install</emphasis> function to
    implement the <emphasis>install</emphasis> task in a recipe and sometimes
    they are provided for you by common classes, such as the autotools class
    providing the default implementations of <emphasis>configure</emphasis>,
    <emphasis>compile</emphasis> and <emphasis>install</emphasis>
    tasks.</para>

    <para>There are several methods available to modify the tasks that are
    being run:</para>

    <variablelist>
      <varlistentry>
        <term>Overriding the default task implementation</term>

        <listitem>
          <para>By defining your own implementation of a task you'll override
          any default or class provided implementations.</para>

          <para>For example, you can define your own implementation of the
          compile task to override any default implementation:<screen>do_compile() {
      oe_runmake DESTDIR=${D}
}</screen></para>

          <para>If you wish to totally prevent the task from running you need
          to define your own empty implementation. This is typically done via
          the definition of the task using a single colon:<screen>do_configure() {
    :
}</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Appending or prepending to the task</term>

        <listitem>
          <para>Sometimes you want the default implementation, but you require
          additional functionality. This can done by appending or pre-pending
          additional functionality onto the task.</para>

          <para>The following example from units shows an example of
          installing an addition file which for some reason was not installed
          via the autotools normal <emphasis>install</emphasis> task:<screen>do_install_append() {
       install -d ${D}${datadir}
       install -m 0655 units.dat ${D}${datadir}
}</screen></para>

          <para>The following example from the cherokee recipe shows an example
          of adding functionality prior to the default
          <emphasis>install</emphasis> task. In this case it compiles a
          program that is used during installation natively so that it will
          work on the host. Without this the autotools default
          <emphasis>install</emphasis> task would fail since it'd try to run
          the program on the host which was compiled for the target:<screen>do_install_prepend () {
        # It only needs this app during the install, so compile it natively
        $BUILD_CC -DHAVE_SYS_STAT_H -o cherokee_replace cherokee_replace.c
}</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Defining a new task</term>

        <listitem>
          <para>Another option is to define a totally new task, and then register
          that with bitbake so that it runs in between two of the existing
          tasks.</para>

          <para>The following example shows a situation in which a cvs tree
          needs to be copied over the top of an extracted tar.gz archive, and
          this needs to be done before any local patches are applied. So a new
          task is defined to perform this action, and then that task is
          registered to run between the existing <emphasis>unpack</emphasis>
          and <emphasis>patch</emphasis> tasks:<screen>do_unpack_extra(){
    cp -pPR ${WORKDIR}/linux/* ${S}
}
addtask unpack_extra after do_unpack before do_patch</screen></para>

          <note>
            <para>The task to add does not have the do_ prepended to it,
            however the tasks to insert it after and before do have the do_
            prepended. No errors will be generated if this is wrong, the
            additional task simply won't be executed.</para>
          </note>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Using overrides</term>

        <listitem>
          <para>Overrides (described fully elsewhere) allow for various
          functionality to be performed conditionally based on the target
          machine, distribution, architecture etc.</para>

          <para>While not commonly used it is possible to use overrides when
          defining tasks. The following example from udev shows an additional
          file being installed for the specified machine only by performing an
          append to the <emphasis>install</emphasis> task for the h2200
          machine only:<screen>do_install_append_h2200() {
    install -m 0644 ${WORKDIR}/50-hostap_cs.rules         ${D}${sysconfdir}/udev/rules.d/50-hostap_cs.rules
}</screen></para>
        </listitem>
      </varlistentry>
    </variablelist>
  </section>

  <section id="recipes_classes" xreflabel="classes">
    <title>Classes: The separation of common functionality</title>

    <para>Often a certain pattern is followed in more than one recipe, or
    maybe some complex python based functionality is required to achieve the
    desired end result. This is achieved through the use of classes, which can
    be found in the classes subdirectory at the top-level of an OE
    checkout.</para>

    <para>Being aware of the available classes and understanding their
    functionality is important because classes:</para>

    <itemizedlist>
      <listitem>
        <para>Save developers time by performing actions that they would
        otherwise need to perform themselves;</para>
      </listitem>

      <listitem>
        <para>Perform a lot of actions in the background making a lot of
        recipes difficult to understand unless you are aware of classes and
        how they work;</para>
      </listitem>

      <listitem>
        <para>A lot of detail on how things work can be learnt from looking at
        how classes are implemented.</para>
      </listitem>
    </itemizedlist>

    <para>A class is used via the inherit method. The following is an example
    for the <emphasis>curl</emphasis> recipe showing that it uses three
    classes:<screen>inherit autotools pkgconfig binconfig</screen>In this case
    it is utilizing the services of three separate classes:</para>

    <variablelist>
      <varlistentry>
        <term>autotools</term>

        <listitem>
          <para>The <xref linkend="autotools_class" /> is used by programs
          that use the GNU configuration tools and takes care of the
          configuration and compilation of the software;</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>pkgconfig</term>

        <listitem>
          <para>The <xref linkend="pkgconfig_class" /> is used to stage the
          <emphasis>.pc</emphasis> files which are used by the <emphasis
          role="bold">pkg-config</emphasis> program to provide information
          about the package to other software that wants to link to this
          software;</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>binconfig</term>

        <listitem>
          <para>The <xref linkend="binconfig_class" /> is used to stage the
          <emphasis>&lt;name&gt;-config</emphasis> files which are used to
          provide information about the package to other software that wants
          to link to this software;</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>Each class is implemented via the file in the <emphasis
    role="bold">classes</emphasis> subdirectory named <emphasis
    role="bold">&lt;classname&gt;.bbclass</emphasis> and these can be examined
    for further details on a particular class, although sometimes it's not
    easy to understand everything that's happening. Many of the classes are
    covered in detail in various sections in this user manual.</para>
  </section>

  <section id="recipes_staging" xreflabel="staging">
    <title>Staging: Making includes and libraries available for
    building</title>

    <para>Staging is the process of making files, such as include files and
    libraries, available for use by other recipes. This is different to
    installing because installing is about making things available for
    packaging and then eventually for use on the target device. Staging on the
    other hand is about making things available on the host system for use in
    building later applications.</para>

    <para>Taking bzip2 as an example you can see that it stages a header file
    and its library files:<screen>do_stage () {
    install -m 0644 bzlib.h ${STAGING_INCDIR}/
    oe_libinstall -a -so libbz2 ${STAGING_LIBDIR}
}</screen></para>

    <para>The <emphasis>oe_libinstall</emphasis> method used in the bzip2
    recipe is described in the <xref linkend="recipes_methods" /> section, and
    it takes care of installing libraries (into the staging area in this
    case). The staging variables are automatically defined to the correct
    staging location, in this case the main staging variables are used:</para>

    <variablelist>
      <varlistentry>
        <term>STAGING_INCDIR</term>

        <listitem>
          <para>The directory into which staged header files should be
          installed. This is the equivalent of the standard <emphasis
          role="bold">/usr/include</emphasis> directory.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>STAGING_LIBDIR</term>

        <listitem>
          <para>The directory into which staged library files should be
          installed. This is the equivalent of the standard <emphasis
          role="bold">/usr/lib</emphasis> directory.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>Additional staging related variables are covered in the <xref
    linkend="directories_staging" /> section in <xref
    linkend="chapter_reference" />.</para>

    <para>Looking in the staging area under tmp you can see the result of the
    bzip2 recipes staging task:<screen>$ <command>find</command> tmp/staging -name '*bzlib*'
tmp/staging/sh4-linux/include/bzlib.h
$ <command>find</command> tmp/staging -name '*libbz*'
tmp/staging/sh4-linux/lib/libbz2.so
tmp/staging/sh4-linux/lib/libbz2.so.1.0
tmp/staging/sh4-linux/lib/libbz2.so.1
tmp/staging/sh4-linux/lib/libbz2.so.1.0.2
tmp/staging/sh4-linux/lib/libbz2.a</screen></para>

    <para>As well as being used during the stage task the staging related
    variables are used when building other packages. Looking at the gnupg
    recipe we see two bzip2 related items:<screen>DEPENDS = "zlib <emphasis
          role="bold">bzip2</emphasis>"
...
EXTRA_OECONF = "--disable-ldap \
        --with-zlib=${STAGING_LIBDIR}/.. \
        <emphasis role="bold">--with-bzip2=${STAGING_LIBDIR}/..</emphasis> \
        --disable-selinux-support"
</screen></para>

    <para>Bzip2 is referred to in two places in the recipe:</para>

    <variablelist>
      <varlistentry>
        <term>DEPENDS</term>

        <listitem>
          <para>Remember that <emphasis role="bold">DEPENDS</emphasis> defines
          the list of build time dependencies. In this case the staged headers
          and libraries from bzip2 are required to build gnupg, and therefore
          we need to make sure the bzip2 recipe has run and staged the
          headers and libraries. By adding the <emphasis
          role="bold">DEPENDS</emphasis> on bzip2 this ensures that this
          happens.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">EXTRA_OECONF</emphasis></term>

        <listitem>
          <para>This variable is used by the <xref
          linkend="autotools_class" /> to provide options to the configure
          script of the package. In the gnupg case it needs to be told where
          the bzip2 headers and libraries are, and this is done via the
          <emphasis>--with-bzip2</emphasis> option. In this case it points to
          the directory which includes the lib and include subdirectories.
          Since OE doesn't define a variable for one level above the include
          and lib directories <emphasis role="bold">..</emphasis> is used to
          indicate one directory up. Without this, gnupg would search the host
          system headers and libraries instead of those we have provided in
          the staging area for the target.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>Remember that staging is used to make things, such as headers and
    libraries, available for use by other recipes later on. While headers and
    libraries are the most common items requiring staging, other items such as
    the pkgconfig files need to be staged as well. For native packages,
    the binaries also need to be staged.</para>
  </section>

  <section id="recipes_autoconf" xreflabel="about autoconf">
    <title>Autoconf: All about autotools</title>

    <para>This section is to be completed:</para>

    <itemizedlist>
      <listitem>
        <para>About building autoconf packages</para>
      </listitem>

      <listitem>
        <para>EXTRA_OECONF</para>
      </listitem>

      <listitem>
        <para>Problems with /usr/include, /usr/lib</para>
      </listitem>

      <listitem>
        <para>Configuring to search in the staging area</para>
      </listitem>

      <listitem>
        <para>-L${STAGING_LIBDIR} vs ${TARGET_LDFLAGS}</para>
      </listitem>

      <listitem>
        <para>Site files</para>
      </listitem>
    </itemizedlist>
  </section>

  <section id="recipes_installation_scripts" xreflabel="installation scripts">
    <title>Installation scripts: Running scripts during package installation and/or
    removal</title>

    <para>Packaging systems such as .ipkg and .deb support pre and post
    installation and pre and post removal scripts which are run during package
    installation and/or package removal on the target system.</para>

    <para>These scripts can be defined in your recipes to enable actions to be
    performed at the appropriate time. Common uses include starting new
    daemons on installation, stopping daemons during uninstall, creating new
    user and/or group entries during install, registering and unregistering
    alternative implementations of commands and registering the need for
    volatiles.</para>

    <para>The following scripts are supported:</para>

    <variablelist>
      <varlistentry>
        <term>preinst</term>

        <listitem>
          <para>The preinst script is run prior to installing the contents of
          the package. During preinst the contents of the package are not
          available to be used as part of the script. The preinst scripts are
          not commonly used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>postinst</term>

        <listitem>
          <para>The postinst script is run after the installation of the
          package has completed. During postinst the contents of the package
          are available to be used. This is often used for the creation of
          volatile directories, registration of daemons, starting of daemons
          and fixing up of SUID binaries.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>prerm</term>

        <listitem>
          <para>The prerm is run prior to the removal of the contents of a
          package. During prerm the contents of the package are still
          available for use by the script.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>postrm</term>

        <listitem>
          <para>The postrm script is run after the completion of the removal
          of the contents of a package. During postrm the contents of the
          package no longer exist and therefore are not available for use by
          the script. Postrm is most commonly used for update alternatives (to
          tell the alternatives system that this alternative is not available
          and another should be selected).</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>Scripts are registered by defining a function for:</para>

    <itemizedlist>
      <listitem>
        <para>pkg_&lt;scriptname&gt;_&lt;packagename&gt;</para>
      </listitem>
    </itemizedlist>

    <para>The following example from ndisc6 shows postinst scripts being
    registered for three of the packages that ndisc6 creates:<screen># Enable SUID bit for applications that need it
pkg_postinst_${PN}-rltraceroute6 () {
    chmod 4555 ${bindir}/rltraceroute6
}
pkg_postinst_${PN}-ndisc6 () {
    chmod 4555 ${bindir}/ndisc6
}
pkg_postinst_${PN}-rdisc6 () {
    chmod 4555 ${bindir}/rdisc6
}</screen></para>

    <note>
      <para>These scripts will be run via <emphasis
      role="bold">/bin/sh</emphasis> on the target device, which is typically
      the busybox sh but could also be bash or some other sh compatible shell.
      As always you should not use any bash extensions in your scripts and
      stick to basic sh syntax.</para>
    </note>

    <para>Note that several classes will also register scripts, and that any
    script you declare will have the script for the classes appended by these
    classes. The following classes all generate additional script
    contents:</para>

    <variablelist>
      <varlistentry>
        <term>update-rc.d</term>

        <listitem>
          <para>This class is used by daemons to register their init scripts
          with the init code.</para>

          <para>Details are provided in the <xref
          linkend="recipes_initscripts" /> section.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>module</term>

        <listitem>
          <para>This class is used by linux kernel modules. It's responsible
          for calling depmod and update-modules during kernel module
          installation and removal.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>kernel</term>

        <listitem>
          <para>This class is used by the linux kernel itself. There is a lot
          of housekeeping required both when installing and removing a kernel
          and this class is responsible for generating the required
          scripts.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>qpf</term>

        <listitem>
          <para>This class is used when installing and/or removing qpf fonts.
          It registers scripts to update the font paths and font cache
          information to ensure that the font information is kept up to date
          as fonts are installed and removed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>update-alternatives</term>

        <listitem>
          <para>This class is used by packages that contain binaries which may
          also be provided by other packages. It tells the system that
          another alternative is available for consideration. The alternatives
          system will create a symlink to the correct alternative from one or
          more available on the system.</para>

          <para>Details are provided in the <xref
          linkend="recipes_alternatives" /> section.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>gtk-icon-cache</term>

        <listitem>
          <para>This class is used by packages that add new gtk icons. It's
          responsible for updating the icon cache when packages are installed
          and removed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>gconf</term>

        <listitem>
          <para></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>package</term>

        <listitem>
          <para>The base class used by packaging classes such as those for
          .ipkg and .deb. The package class may create scripts used to update
          the dynamic linker's ld cache.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>The following example from p3scan shows a postinst script which
    ensures that the required user and group entries exist, and registers the
    need for volatiles (directories and/or files under <emphasis
    role="bold">/var</emphasis>). In addition to explicitly declaring a
    postinst script it uses the update-rc.d class which will result in an
    additional entry being added to the postinst script to register the init
    scripts and start the daemon (via call to update-rc.d as described in the
    <xref linkend="recipes_alternatives" /> section).<screen>inherit autotools update-rc.d

...

# Add havp's user and groups
pkg_postinst_${PN} () {
        grep -q mail: /etc/group || addgroup --system havp
        grep -q mail: /etc/passwd || \
            adduser --disabled-password --home=${localstatedir}/mail --system \
                    --ingroup mail --no-create-home -g "Mail" mail
        /etc/init.d/populate-volatile.sh update
}</screen></para>

    <para>Several scripts in existing recipes will be of the following
    form:<screen>if [ x"$D" = "x" ]; then
    ...
fi</screen></para>

    <para>This is testing if the installation directory, <emphasis
    role="bold">D</emphasis>, is defined and if it is no actions are
    performed. The installation directory will not be defined under normal
    circumstances. The primary use of this test is to permit the application
    to be installed during root filesystem generation. In that situation the
    scripts cannot be run since the root filesystem is generated on the host
    system and not on the target. Any required script actions would need to be
    performed via an alternative method if the package is to be installed in
    the initial root filesystem (such as including any required users and
    groups in the default <emphasis role="bold">passwd</emphasis> and
    <emphasis role="bold">group</emphasis> files for example.)</para>
  </section>

  <section id="recipes_conffiles" xreflabel="conf files">
    <title>Configuration files</title>

    <para>Configuration files that are installed as part of a package require
    special handling. Without special handling as soon as the user upgrades to
    a new version of the package then changes they have made to the
    configuration files will be lost.</para>

    <para>In order to prevent this from happening you need to tell the
    packaging system which files are configuration files. Such files will
    result in the user being asked how they want to handle any
    configuration file changes (if any), as shown in this example:<screen>Downloading http://nynaeve.twibble.org/ipkg-titan-glibc//./p3scan_2.9.05d-r1_sh4.ipk
    Configuration file '/etc/p3scan/p3scan.conf'
    ==&gt; File on system created by you or by a script.
    ==&gt; File also in package provided by package maintainer.
       What would you like to do about it ?  Your options are:
        Y or I  : install the package maintainer's version
        N or O  : keep your currently-installed version
          D     : show the differences between the versions (if diff is installed)
     The default action is to keep your current version.
    *** p3scan.conf (Y/I/N/O/D) [default=N] ?</screen>To declare a file as a
    configuration file you need to define the
    <command>CONFFILES_&lt;pkgname&gt;</command> variable as a whitespace
    separated list of configuration files. The following example from clamav
    shows two files being marked as configuration files:<screen>CONFFILES_${PN}-daemon = "${sysconfdir}/clamd.conf \
                          ${sysconfdir}/default/clamav-daemon"</screen>Note
    the use of <command>${PN}-daemon</command> as the package name. The
    <command>${PN}</command> variable will expand to <command>clamav</command>
    and therefore these conf files are declared as being in the clamav-daemon
    package.</para>
  </section>

  <section id="recipes_package_relationships"
           xreflabel="package relationships files">
    <title>Package relationships</title>

    <para>Explicit relationships between packages are support by packaging
    formats such as ipkg and deb. These relationships include describing
    conflicting packages and recommended packages.</para>

    <para>The following variables control the package relationships in the
    recipes:</para>

    <variablelist>
      <varlistentry>
        <term>RRECOMMENDS</term>

        <listitem>
          <para>Used to specify other packages that are recommended to be
          installed when this package is installed. Generally this means while
          the recommended packages are not required they provide some sort of
          functionality which users would usually want.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>RCONFLICTS</term>

        <listitem>
          <para>Used to specify other packages that conflict with this
          package. Two packages that conflict cannot be installed at the same
          time.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>RREPLACES</term>

        <listitem>
          <para>Used to specify that the current package replaces an older
          package with a different name. During package installation the package
          that is being replaced will be removed since it is no longer needed
          when this package is installed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>RSUGGESTS</term>

        <listitem>
          <para>Used to provide a list of suggested packages to install. These
          are packages that are related to and useful for the current package
          but which are not actually required to use the package.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>RPROVIDES</term>

        <listitem>
          <para>Used to explicitly specify what a package provides at runtime.
          For example hotplug support is provided by several packages, such as
          udev and linux-hotplug. Both declare that they runtime provide
          "hotplug". So any packages that require "hotplug" to work simply
          declare that it RDEPENDS on "hotplug". It's up to the distribution
          to specify which actual implementation of "virtual/hotplug" is
          used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>PROVIDES</term>

        <listitem>
          <para>Used to explicitly specify what a package provides at build
          time. This is typically used when two or more packages can provide
          the same functionality. For example there are several different X
          servers in OpenEmbedded, and each declared as providing
          "virtual/xserver". Therefore a package that depends on an X server
          to build can simply declare that it DEPENDS on "virtual/xserver".
          It's up to the distribution to specify which actual implementation
          of "virtual/xserver" is used.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </section>

  <section id="recipes_fakeroot" xreflabel="fakeroot">
    <title>Fakeroot: Dealing with the need for "root"</title>

    <para>Sometimes packages require root permissions in order to perform
    some action, such as changing user or group owners or creating device
    nodes. Since OpenEmbedded will not keep the user and group information
    it's usually preferable to remove that from the makefiles. For device
    nodes it's usually preferable to create them from the initial device node
    lists or via udev configuration.</para>

    <para>However if you can't get by without root permissions then you can
    use <xref linkend="fakeroot" /> to simulate a root environment, without
    the need to really give root access.</para>

    <para>Using <xref linkend="fakeroot" /> is done by prefixing the
    task:<screen>fakeroot do_install() {</screen>Since this requires fakeroot
    you also need to add a dependency on
    <command>fakeroot-native</command>:<screen>DEPENDS = "fakeroot-native"</screen>See
    the fuse recipe for an example. Further information on <xref
    linkend="fakeroot" />, including a description of how it works, is provided in
    the reference section: <xref linkend="fakeroot" />.</para>
  </section>

  <section id="recipes_native" xreflabel="native">
    <title>Native: Packages for the build host</title>

    <para>This section is to be completed.</para>

    <itemizedlist>
      <listitem>
        <para>What native packages are</para>
      </listitem>

      <listitem>
        <para>Using require with the non-native package</para>
      </listitem>
    </itemizedlist>
  </section>

  <section id="recipes_development" xreflabel="development">
    <title>Development: Strategies for developing recipes</title>

    <para>This section is to be completed.</para>

    <itemizedlist>
      <listitem>
        <para>How to go about developing recipes</para>
      </listitem>

      <listitem>
        <para>How to handle incrementally creating patches</para>
      </listitem>

      <listitem>
        <para>How to deal with site file issues</para>
      </listitem>

      <listitem>
        <para>Strategies for autotools issues</para>
      </listitem>
    </itemizedlist>
  </section>

  <section id="recipes_advanced_versioning" xreflabel="advanced versioning">
    <title>Advanced versioning: How to deal with rc and pre versions</title>

    <para>Special care needs to be taken when specify the version number for
    rc and pre versions of packages.</para>

    <para>Consider the case where we have an existing 1.5 version and there's
    a new 1.6-rc1 release that you want to add.</para>

    <itemizedlist>
      <listitem>
        <para>1.5: Existing version;</para>
      </listitem>

      <listitem>
        <para>1.6-rc1: New version.</para>
      </listitem>
    </itemizedlist>

    <para>If the new package is given the version number 1.6-rc1 then
    everything will work fine initially. However when the final release
    happens it will be called 1.6. If you now create a 1.6 version of the
    package you'll find that the packages are sorted into the following
    order:</para>

    <orderedlist>
      <listitem>
        <para>1.5</para>
      </listitem>

      <listitem>
        <para>1.6</para>
      </listitem>

      <listitem>
        <para>1.6-rc1</para>
      </listitem>
    </orderedlist>

    <para>This results in the packaging system, such as ipkg, considering
    the released version to be older than the rc version.</para>

    <para>In OpenEmbedded the correct naming of pre and rc versions is to use
    the previous version number followed by a + followed by the new version
    number. So the 1.6-rc1 release would be given the version number:</para>

    <itemizedlist>
      <listitem>
        <para>1.5+1.6-rc1</para>
      </listitem>
    </itemizedlist>

    <para>These would result in the eventually ordering being:</para>

    <orderedlist>
      <listitem>
        <para>1.5</para>
      </listitem>

      <listitem>
        <para>1.5+1.6-rc1</para>
      </listitem>

      <listitem>
        <para>1.6</para>
      </listitem>
    </orderedlist>

    <para>This is the correct order and the packaging system will now work as
    expected.</para>
  </section>

  <section id="recipes_require" xreflabel="require">
    <title>Require/include: Reusing recipe contents</title>

    <para>In many packages where you are maintaining multiple versions you'll
    often end up with several recipes which are either identical, or have only
    minor differences between them.</para>

    <para>The require and/or include directive can be used to include common
    content from one file into other. You should always look for a way to
    factor out common functionality into an include file when adding new
    versions of a recipe.</para>

    <note>
      <para>Both require and include perform the same function - including the
      contents of another file into this recipe. The difference is that
      require will generate an error if the file is not found while include
      will not. For this reason include should not be used in new
      recipes.</para>
    </note>

    <para>For example the clamav recipe looks like this:<screen>require clamav.inc

PR = "r0"</screen>Note that all of the functionality of the recipe is provided
    in the clamav.inc file, only the release number is defined in the recipe.
    Each of the recipes includes the same <emphasis
    role="bold">clamav.inc</emphasis> file to save having to duplicate any
    functionality. This also means that as new versions are released it's a
    simple matter of copying the recipe and resetting the release number back
    to zero.</para>

    <para>The following example from iproute2 shows the recipe adding
    additional patches that are not specified by the common included file.
    These are patches only needed for newer release and by only adding them in
    this recipe it permits the common code to be used for both old and new
    recipes:<screen>PR = "r1"

SRC_URI += "file://iproute2-2.6.15_no_strip.diff;striplevel=0 \
            file://new-flex-fix.patch"

require iproute2.inc

DATE = "060323"</screen></para>

    <para>The following example from cherokee shows a similar method of
    including additional patches for this version only. However it also shows
    another technique in which the configure task is defined in the recipe for
    this version, thus replacing the <emphasis>configure</emphasis> task that
    is provided by the common include:<screen>PR = "r7"

SRC_URI_append = "file://configure.patch \
                  file://Makefile.in.patch \
                  file://Makefile.cget.patch \
                  file://util.patch"

require cherokee.inc

do_configure() {
        gnu-configize
        oe_runconf
        sed -i 's:-L\$:-L${STAGING_LIBDIR} -L\$:' ${S}/*libtool
}</screen></para>
  </section>

  <section id="recipes_advanced_python" xreflabel="advanced python">
    <title>Python: Advanced functionality with python</title>

    <para>Recipes permit the use of python code in order to perform complex
    operations which are not possible with the normal recipe syntax and
    variables. Python can be used in both variable assignments and in the
    implementation of tasks.</para>

    <para>For variable assignments python code is indicated via the use of
    <emphasis>${@...}</emphasis>, as shown in the following example:<screen>TAG = ${@bb.data.getVar('PV',d,1).replace('.', '_')}</screen></para>

    <para>The above example retrieves the PV variable from the bitbake data
    object, then replaces any dots with underscores. Therefore if the <emphasis
    role="bold">PV</emphasis> was <emphasis role="bold">0.9.0</emphasis> then
    <emphasis role="bold">TAG</emphasis> will be set to <emphasis
    role="bold">0_9_0</emphasis>.</para>

    <para>Some of the more common python code in use in existing recipes is
    shown in the following list:</para>

    <variablelist>
      <varlistentry>
        <term>bb.data.getVar(&lt;var&gt;,d,1)</term>

        <listitem>
          <para>Retrieve the data for the specified variable from the bitbake
          database for the current recipe.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>&lt;variable&gt;.replace(&lt;key&gt;,
        &lt;replacement&gt;)</term>

        <listitem>
          <para>Find each instance of the key and replace it with the
          replacement value. This can also be used to remove part of a string
          by specifying <emphasis role="bold">''</emphasis> (two single
          quotes) as the replacement.</para>

          <para>The following example would remove the <emphasis
          role="bold">'-frename-registers'</emphasis> option from the
          <emphasis role="bold">CFLAGS</emphasis> variable:<screen>CFLAGS := "${@'${CFLAGS}'.replace('-frename-registers', '')}"</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>os.path.dirname(&lt;filename&gt;)</term>

        <listitem>
          <para>Return the directory only part of a filename.</para>

          <para>This is most commonly seen in existing recipes when setting
          the <emphasis role="bold">FILESDIR</emphasis> variable (as described
          in the <xref linkend="recipes_filespath_dir" /> section). By
          obtaining the name of the recipe file itself, <emphasis
          role="bold">FILE</emphasis>, and then using os.path.dirname to strip
          the filename part:<screen>FILESDIR = "${@os.path.dirname(bb.data.getVar('FILE',d,1))}/make-${PV}"</screen>Note
          however that this is no longer required as <emphasis
          role="bold">FILE_DIRNAME</emphasis> is automatically set to the
          dirname of the <emphasis role="bold">FILE</emphasis> variable and
          therefore this would be written in new recipes as:<screen>FILESDIR = "$FILE_DIRNAME/make-${PV}"</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>&lt;variable&gt;.split(&lt;key&gt;)[&lt;index&gt;]</term>

        <listitem>
          <para>Splits the variable around the specified key. Use <emphasis
          role="bold">[&lt;index&gt;]</emphasis> to select one of the matching
          items from the array generated by the split command.</para>

          <para>The following example from the recipe <emphasis
          role="bold">genext2fs_1.3+1.4rc1.bb</emphasis> would take the
          <emphasis role="bold">PV</emphasis> of <emphasis
          role="bold">1.3+1.4rc1</emphasis> and split it around the <emphasis
          role="bold">+</emphasis> sign, resulting in an array containing
          <emphasis role="bold">1.3</emphasis> and <emphasis
          role="bold">1.4rc1</emphasis>. It then uses the index of <emphasis
          role="bold">[1]</emphasis> to select the second item from the list
          (the first item is at index <emphasis role="bold">0</emphasis>).
          Therefore <emphasis role="bold">TRIMMEDV</emphasis> would be set to
          <emphasis role="bold">1.4rc1</emphasis> for this recipe:</para>

          <screen>TRIMMEDV = "${@bb.data.getVar('PV', d, 1).split('+')[1]}"</screen>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>As well as directly calling built-in python functions, those
    functions defined by the existing classes may also be called. A set of
    common functions is provided by the base class in <emphasis
    role="bold">classes/base.bbclass</emphasis>:</para>

    <variablelist>
      <varlistentry>
        <term>base_conditional</term>

        <listitem>
          <para>This function is used to set a variable to one of two values
          based on the definition of a third variable. The general usage
          is:<screen>${@base_conditional('&lt;variable-name&gt;', '&lt;value&gt;', '&lt;true-result&gt;', &lt;false-result&gt;', d)}"</screen>where:</para>

          <variablelist>
            <varlistentry>
              <term>variable-name</term>

              <listitem>
                <para>This is the name of a variable to check.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>value</term>

              <listitem>
                <para>This is the value to compare the variable
                against.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>true-result</term>

              <listitem>
                <para>If the variable equals the value then this is what is
                returned by the function.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>false-result</term>

              <listitem>
                <para>If the variable does not equal the value then this is
                what is returned by the function.</para>
              </listitem>
            </varlistentry>
          </variablelist>

          <para>The following example from the openssl recipe shows the
          addition of either <emphasis role="bold">-DL_ENDIAN</emphasis> or
          <emphasis role="bold">-DB_ENDIAN</emphasis> depending on the value
          of <emphasis role="bold">SITEINFO_ENDIANNESS</emphasis> which is set
          to le for little endian targets and to be for big endian
          targets:<screen>do_compile () {
    ...
    # Additional flag based on target endianess (see siteinfo.bbclass)
    CFLAG="${CFLAG} ${@base_conditional('SITEINFO_ENDIANNESS', 'le', '-DL_ENDIAN', '-DB_ENDIAN', d)}"
    ...</screen></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>base_contains</term>

        <listitem>
          <para>Similar to base_conditional except that it is checking for the
          value being an element of an array. The general usage is:<screen>${@base_contains('&lt;array-name&gt;', '&lt;value&gt;', '&lt;true-result&gt;', &lt;false-result&gt;', d)}"</screen></para>

          <para>where:<variablelist>
              <varlistentry>
                <term>array-name</term>

                <listitem>
                  <para>This is the name of the array to search.</para>
                </listitem>
              </varlistentry>

              <varlistentry>
                <term>value</term>

                <listitem>
                  <para>This is the value to check for in the array.</para>
                </listitem>
              </varlistentry>

              <varlistentry>
                <term>true-result</term>

                <listitem>
                  <para>If the value is found in the array then this is what
                  is returned by the function.</para>
                </listitem>
              </varlistentry>

              <varlistentry>
                <term>false-result</term>

                <listitem>
                  <para>If the value is not found in the array then this is
                  what is returned by the function.</para>
                </listitem>
              </varlistentry>
            </variablelist>The following example from the task-angstrom-x11
          recipe shows base_contains being used to add a recipe to the runtime
          dependency list but only for machines which have a
          touchscreen:</para>

          <screen>RDEPENDS_angstrom-gpe-task-base := "\
    ...
    ${@base_contains("MACHINE_FEATURES", "touchscreen", "libgtkstylus", "",d)} \
    ...</screen>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>Tasks may be implemented in python by prefixing the task function
    with "python ". In general this should not be needed and should be avoided
    where possible. The following example from the devshell recipe shows how
    the compile task is implemented in python:<screen>python do_compile() {
    import os
    import os.path

    workdir = bb.data.getVar('WORKDIR', d, 1)
    shellfile = os.path.join(workdir, bb.data.expand("${TARGET_PREFIX}${DISTRO}-${MACHINE}-devshell", d))

    f = open(shellfile, "w")

    # emit variables and shell functions
        devshell_emit_env(f, d, False, ["die", "oe", "autotools_do_configure"])

    f.close()
}</screen></para>
  </section>

  <section id="recipes_defaultpreference" xreflabel="default preference">
    <title>Preferences: How to disable packages</title>

    <para>When bitbake is asked to build a package and multiple versions of
    that package are available then bitbake will normally select the version
    that has the highest version number (where the version number is defined
    via the <command>PV</command> variable).</para>

    <para>For example if we were to ask bitbake to build procps and the
    following packages are available:<screen>$ <command>ls</command> recipes/procps
procps-3.1.15/    procps-3.2.1/    procps-3.2.5/    procps-3.2.7/    procps.inc
procps_3.1.15.bb  procps_3.2.1.bb  procps_3.2.5.bb  procps_3.2.7.bb
$</screen>then we would expect it to select version
    <command>3.2.7</command> (the highest version number) to build.</para>

    <para>Sometimes this is not actually what you want to happen though.
    Perhaps you have added a new version of the package that does not yet work
    or maybe the new version has no support for your target yet. Help is at
    hand since bitbake is not only looking at the version numbers to decided
    which version to build but it is also looking at the preference for each
    of those version. The preference is defined via the
    <command>DEFAULT_PREFERENCE</command> variable contained within the
    recipe.</para>

    <para>The default preference (when no
    <command>DEFAULT_PREFERENCE</command> is specified) is zero. Bitbake will
    find the highest preference that is available and then for all the
    packages at the preference level it will select the package with the
    highest version. In general this means that adding a positive
    <command>DEFAULT_PREFERENCE</command> will cause the package to be
    preferred over other versions and a negative
    <command>DEFAULT_PREFERENCE</command> will cause all other packages to be
    preferred.</para>

    <para>Imagine that you are adding procps version 4.0.0, but that it does
    not yet work. You could delete or rename your new recipe so you can build
    a working image, but what you really want to do is just ignore the new 4.0.0
    version until it works. By adding:<screen>DEFAULT_PREFERENCE = "-1"</screen>to
    the recipe this is what will happen. Bitbake will now ignore this version
    (since all of the existing versions have a preference of 0). Note that you
    can still call bitbake directly on the recipe:<screen>bitbake -b recipes/procps/procps_4.0.0.bb</screen>This
    enables you to test, and fix the package manually without having bitbake
    automatically select it normally.</para>

    <para>By using this feature in conjunction with overrides you can also
    disable (or select) specific versions based on the override. The following
    example from glibc shows that this version has been disabled for the sh3
    architecture because it doesn't support sh3. This will force bitbake to
    try and select one of the other available versions of glibc
    instead:<screen>recipes/glibc/glibc_2.3.2+cvs20040726.bb:DEFAULT_PREFERENCE_sh3 = "-99"</screen></para>
  </section>

  <section id="recipes_initscripts" xreflabel="initscripts">
    <title>Initscripts: How to handle daemons</title>

    <para>This section is to be completed.</para>

    <itemizedlist>
      <listitem>
        <para>update-rc.d class</para>
      </listitem>

      <listitem>
        <para>sh syntax</para>
      </listitem>

      <listitem>
        <para>stop/stop/restart params</para>
      </listitem>

      <listitem>
        <para>sample/standard script?</para>
      </listitem>

      <listitem>
        <para>volatiles</para>
      </listitem>
    </itemizedlist>
  </section>

  <section id="recipes_alternatives" xreflabel="alternatives">
    <title>Alternatives: How to handle the same command in multiple
    packages</title>

    <para>Alternatives are used when the same command is provided by multiple
    packages. A classic example is busybox, which provides a whole set of
    commands such as <emphasis role="bold">/bin/ls</emphasis> and <emphasis
    role="bold">/bin/find</emphasis>, which are also provided by other
    packages such as coreutils (<emphasis role="bold">/bin/ls</emphasis>) and
    findutils (<emphasis role="bold">/bin/find</emphasis>).</para>

    <para>A system for handling alternatives is required to allow the user to
    choose which version of the command they wish to have installed. It should
    be possible to install either one, or both, or remove one when both are
    installed etc, and to have no issues with the packages overwriting files
    from other packages.</para>

    <para>The most common reason for alternatives is to reduce the size of the
    binaries. By cutting down on features, built in help, error messages
    and combining multiple binaries into one large binary it's possible to
    save considerable space. Often users are not expected to use the commands
    interactively in embedded appliances and therefore these changes have no
    visible effect to the user. In some situations users may have interactive
    access, or they may be more advanced users who want shell access on
    appliances that normally don't provide it, and in these cases they should be
    able to install the full functional version if they desire.</para>

    <section>
      <title>Example of alternative commands</title>

      <para>Most distributions include busybox in place of the full featured
      version of the commands. The following example shows a typical install
      in which the find command, which we'll use as an example here, is the
      busybox version:<screen>root@titan:~$ find --version
find --version
BusyBox v1.2.1 (2006.12.17-05:10+0000) multi-call binary

Usage: find [PATH...] [EXPRESSION]

root@titan:~$ which find
which find
/usr/bin/find</screen>If we now install the full version of find:<screen>root@titan:~$ ipkg install findutils
ipkg install findutils
Installing findutils (4.2.29-r0) to root...
Downloading http://nynaeve.twibble.org/ipkg-titan-glibc//./findutils_4.2.29-r0_sh4.ipk
Configuring findutils

update-alternatives: Linking //usr/bin/find to find.findutils
update-alternatives: Linking //usr/bin/xargs to xargs.findutils</screen></para>

      <para>Then we see that the standard version of find changes to the full
      featured implementation:<screen>root@titan:~$ find --version
find --version
GNU find version 4.2.29
Features enabled: D_TYPE O_NOFOLLOW(enabled) LEAF_OPTIMISATION
root@titan:~$ which find
which find
/usr/bin/find</screen></para>
    </section>

    <section>
      <title>Using update-alternatives</title>

      <para>Two methods of using the alternatives system are available:</para>

      <orderedlist>
        <listitem>
          <para>Via the <xref linkend="update-alternatives_class" />. This is
          the simplest method, but is not usable in all situations.</para>
        </listitem>

        <listitem>
          <para>Via directly calling the update-alternatives command.</para>
        </listitem>
      </orderedlist>

      <para>The <xref linkend="update-alternatives_class" /> provides
      the simplest method of using alternatives but it only works for a single
      alternative. For multiple alternatives they need to be manually
      registered during post install.</para>

      <para>Full details on both methods is provided in the <xref
      linkend="update-alternatives_class" /> section of the reference
      manual.</para>
    </section>
  </section>

  <section id="recipes_volatiles" xreflabel="volatiles">
    <title>Volatiles: How to handle the /var directory</title>

    <para>The <emphasis role="bold">/var</emphasis> directory is for storing
    volatile information, that is information which is constantly changing and
    which in general may be easily recreated. In embedded applications it is
    often desirable that such files are not stored on disk or flash for
    various reasons including:</para>

    <itemizedlist>
      <listitem>
        <para>The possibility of a reduced lifetime of the flash;</para>
      </listitem>

      <listitem>
        <para>The limited amount of storage space available;</para>
      </listitem>

      <listitem>
        <para>To ensure filesystem corruption cannot occur due to a sudden
        power loss.</para>
      </listitem>
    </itemizedlist>

    <para>For these reasons many of the OpenEmbedded distributions use a tmpfs
    based memory filesystem for <emphasis role="bold">/var</emphasis> instead
    of using a disk or flash based filesystem. The consequence of this is that
    all contents of the <emphasis role="bold">/var</emphasis> directory is
    lost when the device is powered off or restarted. Therefore special
    handling of <emphasis role="bold">/var</emphasis> is required in all
    packages. Even if your distribution does not use a tmpfs based <emphasis
    role="bold">/var</emphasis> you need to assume it does when creating
    packages to ensure the package can be used on those distributions that do
    use a tmpfs based <emphasis role="bold">/var</emphasis>. This special
    handling is provided via the <emphasis
    role="bold">populate-volatiles.sh</emphasis> script.</para>

    <note>
      <para>If your package requires any files, directories or symlinks in
      <emphasis role="bold">/var</emphasis> then it should be using the
      populate-volatiles facilities.</para>
    </note>

    <section>
      <title>Declaring volatiles</title>

      <para>This section is to be completed.</para>

      <itemizedlist>
        <listitem>
          <para>how volatiles work</para>
        </listitem>

        <listitem>
          <para>default volatiles</para>
        </listitem>

        <listitem>
          <para>don't include any /var stuff in packages</para>
        </listitem>

        <listitem>
          <para>even if your distro doesn't use /var in tmpfs, others do</para>
        </listitem>

        <listitem>
          <para>updating the volatiles cache during install</para>
        </listitem>
      </itemizedlist>
    </section>

    <section>
      <title>Logging and log files</title>

      <para>As a consequence of the volatile and/or small capacity of the
      <emphasis role="bold">/var</emphasis> file system some distributions
      choose methods of logging other than writing to a file. The most typical
      is the use of an in-memory circular log buffer which can be read using
      the <emphasis role="bold">logread</emphasis> command.</para>

      <para>To ensure that each distribution is able to implement logging in a
      method that is suitable for its goals all packages should be configured
      by default to log via syslog, and not log directly to a file, if
      possible. If the distribution and/or end-user requires logging to a file
      then they can configure syslog and/or your application to implement
      this.</para>
    </section>

    <section>
      <title>Summary</title>

      <para>In summary the following are required when dealing with
      <command>/var</command>:</para>

      <itemizedlist>
        <listitem>
          <para>Configure all logging to use syslog whenever possible. This
          leaves the decision on where to log up to the individual
          distributions.</para>
        </listitem>

        <listitem>
          <para>Don't include any <command>/var</command> directories, files or
          symlinks in packages. They would be lost on a reboot and so should
          not be included in packages.</para>
        </listitem>

        <listitem>
          <para>The only directories that you can assume exist are those
          listed in the default volatiles file:
          <command>recipes/initscripts/initscripts-1.0/volatiles</command>.</para>
        </listitem>

        <listitem>
          <para>For any other directories, files or links that are required in
          <command>/var</command> you should install your own volatiles list
          as part of the package.</para>
        </listitem>
      </itemizedlist>
    </section>
  </section>

  <section id="recipes_misc">
    <title>Miscellaneous</title>

    <para>This section is to be completed.</para>

    <itemizedlist>
      <listitem>
        <para>about optimization</para>
      </listitem>

      <listitem>
        <para>about download directories</para>
      </listitem>

      <listitem>
        <para>about parallel builds</para>
      </listitem>

      <listitem>
        <para>about determining endianess (aka net-snmp, openssl, hping etc
        style)</para>
      </listitem>

      <listitem>
        <para>about PACKAGES_DYNAMIC</para>
      </listitem>

      <listitem>
        <para>about LEAD_SONAME</para>
      </listitem>

      <listitem>
        <para>about "python () {" - looks like it is always run when a recipe
        is parsed? see pam/libpam</para>
      </listitem>

      <listitem>
        <para>about SRCDATE with svn/cvs?</para>
      </listitem>

      <listitem>
        <para>about INHIBIT_DEFAULT_DEPS?</para>
      </listitem>

      <listitem>
        <para>about COMPATIBLE_MACHINE and COMPATIBLE_HOST</para>
      </listitem>

      <listitem>
        <para>about SUID binaries, and the need for postinst to fix them
        up</para>
      </listitem>

      <listitem>
        <para>about passwd and group (some comment in install scripts section
        already).</para>
      </listitem>
    </itemizedlist>

    <para></para>
  </section>
</chapter>