> - #!/usr/bin/env > #!/bin/bash for portability

Yes... but do not take that as a "cargo cult script shebang".

If you're a sysadmin writing a script for a company with 2k linux servers, that has a policy of "we only use linux version Foo X"... and we do not use other bash in the system than /bin/bash (no bash compiled by hand, no multiple versions of bash, etc)... then portability via "env" does not make sense.

If you have two laptops and a raspberry at home, with debian or arch, and you write a script for yourself... then portability via "env" does not make sense.

And last but not least... using env is slower.

See:

    strace -fc /bin/bash -c ':'

Vs

    strace -fc /usr/bin/env bash -c ':'

On my system, that's 92 syscalls and 3 errors, Vs 152 syscalls and 8 errors.

Just to start procesing.

Diferent levels of system bloat (environment, library paths, etc) can give different results than my example.

And as others said... if you're not using GNU/bash syntax and the script is really simple, the best for portbility is to go with /bin/sh.

    strace -fc /bin/sh -c ':'

On my system 41 syscalls and 1 error... (and less RAM, CPU and pagefaults).

If you're not using associative arrays, array indexes, non POSIX builtin options, and other bash extensions... if the script is just to join a few commands and variables... it pays the effort to write it in simple sh, both, for portability and performance.