MINOR: config: add predicate "defined()" to conditional expression blocks
"defined(name)" will return true if <name> is a defined environment variable
otherwise false, regardless of its contents.
diff --git a/doc/configuration.txt b/doc/configuration.txt
index a6af2f2..ff90526 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -807,9 +807,20 @@
- an empty string, always returns "false"
- the integer zero ('0'), always returns "false"
- a non-nul integer (e.g. '1'), always returns "true".
+ - a predicate optionally followed by argument(s) in parenthesis.
+
+The list of currently supported predicates is the following:
+
+ - defined(<name>) : returns true if an environment variable <name>
+ exists, regardless of its contents
+
+Example:
-Other patterns are not supported yet but the purpose is to bring a few
-functions to test for certain build options and supported features.
+ .if defined(HAPROXY_MWORKER)
+ listen mwcli_px
+ bind :1111
+ ...
+ .endif
Three other directives are provided to report some status: