At sign after shebang?

Question

In the Apache httpd project's "support/apxs.in" script, a text surrounded with @ signs comes after #!. That is, the first line of the script is:

#!@perlbin@ -w

Is this a Perl thing or a UNIX kernel thing? In other words, it it possible to execute this script using path/to/script/script_name.in?

If not, then what is the reason to start the script with a #!?

those are [`.in` files](http://unix.stackexchange.com/q/84380) (i.e. templates) — don_crissti, Feb 02 '17 at 18:50
As a side note, `@` is fine in filenames so **if** you have an executable called `@perlbin@` which accepts the `-w` option and is able to interpret the contents of that file, then *yes* you can run that file. — Bakuriu, Feb 03 '17 at 13:05

Kusalananda · Accepted Answer · 2017-02-03T17:32:08.103

47

This looks like a placeholder in an GNU Automake template which is going to be filled in by a configure script. So it's neither a Perl or Unix kernel thing, but a GNU autotools thing.

It is probably from a file in a source distribution, not from a file that was installed on the system through make install or a package manager.

Alternatively, it's from a broken build with GNU autotools that never defined perlbin properly.

That the file has a .in suffix confirms that it is supposed to be processed by configure.

No, you can not execute this file as it is. The placeholder will be replaced with the proper path to the perl executable when you run configure.

edited Feb 03 '17 at 17:32

answered Feb 02 '17 at 19:01

Kusalananda

320,670
36
633
936

Yeah the link in the question leads to a source code repository. – Lightness Races in Orbit Feb 03 '17 at 17:22
@LightnessRacesinOrbit You know what, I didn't even see that there was a link there. – Kusalananda Feb 03 '17 at 17:24
1

Hehe I thought that may have been the case. I have suggested an edit that fixes a couple of problems with it, this being one of them :) – Lightness Races in Orbit Feb 03 '17 at 17:29
1

Seems like a problem with the styling of Unix.SE -- the link color isn't very distinct from the normal text color. – Barmar Feb 08 '17 at 18:56
@Barmar It's not the first time I miss a link that's not explicitly advertised as a link. – Kusalananda Feb 08 '17 at 18:57
1

[meta question about link color](http://meta.unix.stackexchange.com/questions/4220/make-link-colors-brighter-and-or-add-dotted-underline) – Barmar Feb 08 '17 at 19:23

At sign after shebang?

1 Answers1