TIL: Some surprising code execution sources in bash

I ran across two surprising sources of code execution in bash (and probably other shells) recently. In a historic context these probably weren't too serious of a problem, but in the context of CI systems where everything is a rats' nest of shell and YAML they could be useful execution primitives. Edit 2024-11-22: the Bash Pitfalls page in the Wooledge Bash Guide contains examples of these, among o