Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=47656

Add information on system property replacement in config files.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@889615 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/webapps/docs/config/index.xml b/webapps/docs/config/index.xml
index 3969a77..83e40a2 100644 (file)
--- a/webapps/docs/config/index.xml
+++ b/webapps/docs/config/index.xml
@@ -39,6 +39,14 @@ attempt to describe which configuration directives should be used to perform
 specific tasks - for that, see the various <em>HOW-TO</em> documents on the
 main index page.</p>
 
+<p>The Tomcat configuration files support Apache Ant style variable
+substitution. A system property with the name <code>propname</code> may be
+used in a configuration file using the syntax <code>${propname}</code>. All
+system properties are available including those set using the <code>-D</code>
+syntax, those automatically made available by the JVM and those configured in
+the <code>$CATALINA_BASE/conf/catalina.properties</code> file.
+</p>
+
 <p>The configuration element descriptions are organized into the following
 major categories:</p>
 <ul>