From: Akinori MUSHA <knu@...>
Date: 2009-11-10T01:10:02+09:00
Subject: [ruby-core:26655] Re: [Bug #2351] system() hardlinked to /bin/sh

--pgp-sign-Multipart_Tue_Nov_10_01:09:24_2009-1
Content-Type: text/plain; charset=US-ASCII

At Mon, 9 Nov 2009 23:41:29 +0900,
Marcus Franke wrote:
> I encountered this problem while using a feature of the very powerful zsh(ell).
>
> In zsh one can use regular expressions in shell commands, like accessing files in
> different locations with one command:
>
> cat -la /mnt/server(1|2)/some/path/and/file_log

The /bin/sh is hardcoded in system() because it is the only shell on
Unix-like systems you can rely on, and it is a good thing to fix the
shell in terms of writing a portable program.  For example, sh and csh
are so different you don't even have a common way to redirect stderr
output.

> Example:
>  % irb
>  >> ENV['SHELL']
>  => "/usr/bin/zsh"
>  >> system('cat /mnt/server(1|2|3)/file | sed, awk, etc.')
>  sh: Syntax error: "(" unexpected
>  => false

If you need to run a command-line that relies on a specific shell, you
can and should specify it.

system('/bin/zsh', '-c', 'cat /mnt/server(1|2|3)/file | sed, awk, etc.');

Or if you mean you want to run a command-line with the user's shell:

system(ENV['SHELL'], '-c', command_line);


I think the problem here is a documentation flaw.  The desciption of
system() should explicitly say that the method will call the standard
shell of the running system, which is /bin/sh on Unix family systems
(including Cygwin) and cmd.exe on Windows family systems.

--
Akinori MUSHA / http://akinori.org/

--pgp-sign-Multipart_Tue_Nov_10_01:09:24_2009-1
Content-Type: application/pgp-signature
Content-Transfer-Encoding: 7bit

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.10 (FreeBSD)

iEYEABECAAYFAkr4PrQACgkQkgvvx5/Z4e5wpgCbBbrGPtbdWn+QM+cEs/+M5XZK
0JcAoMTgJMq6E7ymekSJwwkEOgsh/95R
=2ZB4
-----END PGP SIGNATURE-----

--pgp-sign-Multipart_Tue_Nov_10_01:09:24_2009-1--