Bug #365439: Add set_unless_changed() and unset_unless_changed().

1 files changed, 17 insertions, 3 deletions

diff --git a/man/portage.5 b/man/portage.5
index fc51481d1..a210e8d2d 100644
--- a/man/portage.5
+++ b/man/portage.5
@@ -1,4 +1,4 @@
-.TH "PORTAGE" "5" "Feb 2011" "Portage VERSION" "Portage"
+.TH "PORTAGE" "5" "May 2011" "Portage VERSION" "Portage"
 .SH NAME
 portage \- the heart of Gentoo
 .SH "DESCRIPTION"
@@ -674,8 +674,22 @@ In this directory additional package\-specific bashrc files can be created.
 Note that if package\-specific environment variable settings are all that's
 needed, then \fB/etc/portage/package.env\fR should be used instead of the
 bashrc approach that is described here.
-Portage will source all of them after \fB/etc/portage/bashrc\fR in the following
-order:
+
+set_unless_changed and unset_unless_changed functions can be used to set or
+unset given variables only if these variable have not been set to values
+different than values set in make.conf. This functionality can be useful for
+temporary overriding of these variables during emerge invocation. Variables
+set in the usual VARIABLE=VALUE style will unconditionally override variables
+set during emerge invocation.
+
+.I Syntax:
+.nf
+set_unless_changed VARIABLE VALUE
+unset_unless_changed VALUE
+.fi
+
+Portage will source all of these bashrc files after \fB/etc/portage/bashrc\fR
+in the following order:
 .nr step 1 1
 .IP \n[step]. 3
 /etc/portage/env/${CATEGORY}/${PN}