What is the proper way to make a bash script portable between Linux and FreeBSD?

Question

I am working on some bash scripts that I'd like to work across my Linux and FreeBSD systems.

Since I mostly work in Linux, I am used to starting my bash scripts with

#!/bin/bash

But this doesn't work on FreeBSD since bash lives at /usr/local/bin/bash. So on FreeBSD my scripts need to start with

#!/usr/local/bin/bash

So is there something else I could use that would be portable across both systems? I'd rather not maintain two versions of the scripts.

Answer 1

#!/usr/bin/env bash

should do the trick, provided that bash is on the path somewhere. See here for more details.

Answer 2

Honestly, if you want portability, invoke as /bin/sh and code to POSIX. It's less pretty, but you will run into fewer potential issues if you do.