document RRD_DEFAULT_FONT environment variable

git-svn-id: svn://svn.oetiker.ch/rrdtool/branches/1.2/program@364 a5681a0c-68f1-0310-ab6d-d61299d08faa

diff --git a/doc/rrdgraph.src b/doc/rrdgraph.src
index b829a7b..69a2fc9 100644 (file)
--- a/doc/rrdgraph.src
+++ b/doc/rrdgraph.src
@@ -317,6 +317,9 @@ for the graph legend.
 
 Use Times for the title: C<--font TITLE:13:/usr/lib/fonts/times.ttf>
 
+RRDtool comes with a preset default font. You can set the environment
+variable C<RRD_DEFAULT_FONT> if you want to change this.
+
 B<[-a|--imgformat C<PNG>|C<SVG>|C<EPS>|C<PDF>]>
 
 Image format for the generated graph.