[prg318]

So long as you don't need to "source" any of these POSIX-compliant scripts into your environment... A shebang'd script cannot affect the environment of the parent process

[ronjouch]

Indeed, thanks for the precision. Never ran into that, though; config.fish is the only thing touching my environment.

[prg318]

Lucky for you. I have really come to love zsh's sh and ksh emulation features for this very reason. I have worked in various work environments where setting up a build environment or a testing environment required sourcing ksh scripts that sourced even more ksh scripts. The majority of the engineers on these teams would "deal with" ksh for this reason but a few of the "geekier" engineers would set up zsh with ksh emulation in order to work in a more usable shell.