More specifically, every shell script should have "set -eu" at its second line, directly after the sh'bang line:
#!...
set -eu
#!...
set -euvxDo you have a strong reason to prefer "set" over shebang flags? I have a slight preference for shebang flags so I can deliberately override them from the command line (but it's not a hill I'd die on):
$ cat foo
#!/bin/bash -eu
cd /nowhere
echo 'still here'
$ ./foo
./foo: line 2: cd: nowhere: No such file or directory
$ bash -c ./foo # thinking about system(3)
./foo: line 2: cd: nowhere: No such file or directory
$ bash +e ./foo # override
./foo: line 2: cd: nowhere: No such file or directory
still here
$
https://google.github.io/styleguide/shell.xml?showone=Which_...
So the portable sh'bang line for bash is:
#!/usr/bin/env bash
So
#!/usr/bin/env bash
set -eu
#!/bin/sh -euNitpick: on every BSD system I've used, it's /usr/local/bin/bash. But I definitely agree that using /usr/bin/env bash is the preferred solution for when you want to use bash (although I don't think it's even installed by default on most BSD's); as an Arch user (where /usr/bin/python is symlinked to python3 rather than python2), I appreciate those who go out of their way to use proper, portable shebangs.
#!/bin/sh -eu