Yes, it’s true that #!/usr/bin/env bash is a more reliable way to get bash, but you mentioned that you wanted a POSIX shell, not that you specifically needed bash, so #!/bin/sh will work on any system including NixOS.
Also, export a=bdoes work in Fish. But you don’t have to use it if you don’t know how it works.
Actually,
/bin/shis available on NixOS 🤓Yes, it’s true that
#!/usr/bin/env bashis a more reliable way to get bash, but you mentioned that you wanted a POSIX shell, not that you specifically needed bash, so#!/bin/shwill work on any system including NixOS.Also,
export a=bdoes work in Fish. But you don’t have to use it if you don’t know how it works.