Index: source.c
===================================================================
RCS file: /cvs/src/src/gdb/source.c,v
retrieving revision 1.76
diff -u -p -r1.76 source.c
--- source.c	8 Aug 2006 22:06:06 -0000	1.76
+++ source.c	12 Jan 2007 06:32:06 -0000
@@ -1997,16 +2007,26 @@ Show number of source lines gdb will lis
 
   add_cmd ("substitute-path", class_files, set_substitute_path_command,
            _("\
-Add a source path substitution rule.  If a substitution rule was previously\n\
-set, it is overridden."), &setlist);
+set substitute-path FROM TO\n\
+Add a source path substitution rule replacing FROM into TO in source paths.\n\
+If a substitution rule was previously set for FROM, the old rule is replaced\n\
+by the new one."),
+           &setlist);
 
   add_cmd ("substitute-path", class_files, unset_substitute_path_command,
            _("\
-Remove the current source path substitution rule.  This has no effect\n\
-if no path substitution rule was previously specified."),
+unset substitute-path [FROM]\n\
+If a path is specified (FROM), delete the associated rule from the current\n\
+list of substitution rules.  A warning is emmitted by the debugger if\n\
+no rule could be found.\n\
+If no path is specified, then all substitution rules are deleted."),
            &unsetlist);
 
   add_cmd ("substitute-path", class_files, show_substitute_path_command,
-           _("Show the current source path substitution rule."),
+           _("\
+show substitute-path [FROM]\n\
+If a path is specified (FROM), print the source path substitution rule which\n\
+would rewrite that path.\n\
+If no path is specified, print all source path substitution rules."),
            &showlist);
 }