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authorJamie Lenehan <lenehan@twibble.org>2006-08-28 00:14:20 +0000
committerJamie Lenehan <lenehan@twibble.org>2006-08-28 00:14:20 +0000
commit5e78e83f9caba3e8633c8362b4776f2ff127e160 (patch)
tree294df7395df1820c97f16832720a25f06c85ffb5 /usermanual/reference
parent0dad985a7a48ba2a239fdb9a29e4e349309c80d7 (diff)
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usermanual class_autotools: Document the site file syntax, in particular
mention the use of the shell syntax for conditionally setting a variable only if teh variable is not already set.
Diffstat (limited to 'usermanual/reference')
-rw-r--r--usermanual/reference/class_autotools.xml11
1 files changed, 11 insertions, 0 deletions
diff --git a/usermanual/reference/class_autotools.xml b/usermanual/reference/class_autotools.xml
index 36b377a14a..e4ed62ece0 100644
--- a/usermanual/reference/class_autotools.xml
+++ b/usermanual/reference/class_autotools.xml
@@ -114,6 +114,17 @@ do_install_append () {
</listitem>
</orderedlist>
+ <para>All site files are shell scripts which are run by autoconf and
+ therefore the syntax is the same as you would use in sh. There are two
+ current methods of settings variables that is used in the existing site
+ files. This include explicitly settings the value of the variable:<screen>ac_cv_sys_restartable_syscalls=yes</screen>and
+ conditionally setting the value of the variable:<screen>ac_cv_uchar=${ac_cv_uchar=no}</screen>The
+ conditional version is using shell syntax to say "<emphasis>only set this
+ to the specified value if it is not currently set</emphasis>". The
+ conditional version allows the variable to be set in the shell prior to
+ calling configure and it will then not be replaced by the value from the
+ site file.</para>
+
<para>Sometimes it's useful to manually check values from the site file.
This can prove useful in situations where autotools is not used but you
still need some of the same information that an autotools configure script