Merge pull request #12 from glennj/UUID-validation-for-bash

Fix UUID validity check for bash. Closes #9.

xr.sh

@@ -86,7 +86,7 @@ function _src_track() {
 
 # Tests whether the given string is a valid UUID or not.
 function _is_uuid() {
-    [[ "$1" =~ '^[a-z0-9]{32}$' ]]
+    [[ "$1" =~ ^[[:xdigit:]]{32}$ ]]
 }
 
 # Public function.