diff --git a/document/linux/config/bash/module/autocomplete.sh b/document/linux/config/bash/module/autocomplete.sh
index 78fa209..e6cad74 100644
--- a/document/linux/config/bash/module/autocomplete.sh
+++ b/document/linux/config/bash/module/autocomplete.sh
@@ -1,3 +1,6 @@
+# bash autocomplete.
+# usage: complete -F _foo foo
+# there are also options like -o nospace. see man for more info.
 autocomplete()
 {
   local commands="$@"