Portable shebang line

Question

#!/usr/bin/perl

This is the shebang line to a lot of scripts I'm writing lately.

Hard coding the path of the binary seems like it could create some problems. For instance, if one of my users has Perl installed at /something_else/bin then they'd have to change all the shebangs.

I've seen some tools that will automatically replace the shebangs, but I'm wondering if there is something simpler.

score 16 · Accepted Answer · answered May 17 '10 at 00:23

16

env(1)

#!/usr/bin/env perl

answered May 17 '10 at 00:23

Ignacio Vazquez-Abrams

776,304
153
1,341
1,358

what is /usr/bin/env is somewhere else on their system? – Mike May 17 '10 at 00:25
2

Then it most likely will be there *as well as* in `/usr/bin`. – Ignacio Vazquez-Abrams May 17 '10 at 00:30
You *could* maybe just use "#!env perl" of "#!perl" and rely on the path being set (But I don't like it). – Brenton Alker May 17 '10 at 00:31
4

@Brenton, sorry $PATH is not parsed by #!. – Joshua May 17 '10 at 00:46
1

Ah, true... knew there had to be a reason I hadn't ever seen it done :) – Brenton Alker May 17 '10 at 01:00
Works for plain `#!/usr/bin/perl`, but if you need to pass an option to perl (e.g. `#!/usr/bin/env perl -lp`) it will fail on many systems because the kernel can only handle up to one argument. This is in line with the UNIX motto: *Why Solve the Problem Properly?* – j_random_hacker Sep 01 '11 at 01:50
Related information: [Why is #!/usr/bin/env bash superior to #!/bin/bash?](https://stackoverflow.com/questions/21612980/why-is-usr-bin-env-bash-superior-to-bin-bash) – ynn Jan 01 '20 at 09:29

score 1 · Answer 2 · edited May 23 '17 at 12:16

1

For odd embedded systems where env is not in /usr/bin/env (E.g. NAS boxes running funplug etc) this might work. Based on the ActivePerl / DOS trick

#!/bin/sh
exec perl -x -S "$0" "$@"
#!perl
print "hello";

edited May 23 '17 at 12:16

Community

1
1

answered Apr 07 '12 at 13:35

ydrol

139
1
3

Portable shebang line

2 Answers2