@fanf@mendeddrum.org I've been writing shell scripts for 50 years, and still use the "x-hack" (muscle memory!). As mentioned in the comments, the main use was for testing empty variables. The hack shouldn't be dismissed too readily - there are still commercial systems running with ancient shells where the hack is still needed. Even as various Bourne-style shells were fixed, you still needed the hack to write portable scripts where you didn't know which specific shell would be used to run it. Vive la "x"!