[oe-commits] org.oe.documentation usermanual class_autotools: Document the site file syntax, in particular

[lenehan commit]

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.

Author: lenehan at openembedded.org
Branch: org.openembedded.documentation
Revision: e49f3539929602ea80e545f168e045116c000378
ViewMTN: http://monotone.openembedded.org/revision.psp?id=e49f3539929602ea80e545f168e045116c000378
Files:
1
usermanual/reference/class_autotools.xml
Diffs:

#
# mt diff -rc23c92a45bf75bf4253fa4f05175a4aed000a601 -re49f3539929602ea80e545f168e045116c000378
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# 
# 
# patch "usermanual/reference/class_autotools.xml"
#  from [79ebe0ad5dc5bbee6497bfd946a89eea7cf90770]
#    to [89f48232bbcd846de7167fe39469e653090781dd]
# 
============================================================
--- usermanual/reference/class_autotools.xml	79ebe0ad5dc5bbee6497bfd946a89eea7cf90770
+++ usermanual/reference/class_autotools.xml	89f48232bbcd846de7167fe39469e653090781dd
@@ -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