Adding to this, it's not just bash you have to worry about: also grep, wc, head, cut, and all other external utilities you're calling.
There are actually quite a few incompatibilities between different implementations and versions of many of those utilities. Even if you try your best to restrict to the POSIX standard it's quite easy to "accidentally" use an extension, leading to breakage when someone runs it on Linux distro $foo or macOS.
Dependencies is a big problem in shell scripts, much more so than most other environments.
There are actually quite a few incompatibilities between different implementations and versions of many of those utilities. Even if you try your best to restrict to the POSIX standard it's quite easy to "accidentally" use an extension, leading to breakage when someone runs it on Linux distro $foo or macOS.
Dependencies is a big problem in shell scripts, much more so than most other environments.