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Comment by njharman | Hacker News Reader

No a lot of stuff broke because people depended on implicit rather than being explicit.

    #!/bin/bash

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  wilya@home $ /bin/bash
  zsh: no such file or directory: /bin/bash
  wilya@home $ which bash
  /usr/local/bin/bash

(Yes, I'm annoyed when I see #!/bin/bash, especially on scripts which are otherwise basic enough to be portable everywhere)

It is still better to write #!/bin/bash for bashism using scripts than #!/bin/sh. I recently had to run sed -i (well, another GNUism) 1s%/sh%/bash% on bunch of customer's scripts to make them work on debian. At least when script wants /bin/bash it is going to fail cleanly (and not in the middle after modifying random things) and with mostly meaningful error.

It's probably safer to use:

    #!/usr/bin/env bash

Assuming env is installed (I believe I had to install a package on OpenBSD to use it) this will find the first instance of bash in the PATH.

How do you know env is in /usr/bin rather than in /bin or /usr/local/bin? I'm just curious...

You don't, but I've run into more problems with bash being in unexpected places than env.

Right on, thanks.

Good question. I've used systems, e.g. AIX, where env(1) was in /bin.

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