From: akr <akr@...>
Date: 2012-03-18T15:22:36+09:00
Subject: [ruby-core:43396] [ruby-trunk - Feature #2715] Optimization to avoid spawning shell in Kernel#system call should check for failure conditions


Issue #2715 has been updated by akr.

Description updated

I feel the optimization (avoid shell when no meta characters) can be removed.

We have many ways to avoid shell such as system(command, arg1, arg2).

And recent computers are fast enough to run command via shell.
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Feature #2715: Optimization to avoid spawning shell in Kernel#system call should check for failure conditions
https://bugs.ruby-lang.org/issues/2715#change-24705

Author: taw
Status: Feedback
Priority: Normal
Assignee: 
Category: core
Target version: 


=begin
 This is an old issue, I think going all the way back to Perl's system().
 
 Kernel#system is supposed to spawn shell and pass its argument to shell process just like C system(); except it's optimized for a common case of very simple argument, in which case Ruby (like Perl) simply does fork and exec of the string passed, split on whitespace.
 
 This almost works, except shell error reporting is not duplicated. If command doesn't exist, shell would print an error message on stderr, while Ruby like Perl fails silently.
 
 Problem is present in all versions of Ruby including 1.8.7 and 1.9.1.
 
 To reproduce:
 $ ruby -e 'system "fail"'
 $ ruby -e 'system "\"\"fail"'
 sh: fail: command not found
 
 Output of both commands should be identical (or at least close enough, details of error message might differ by Unix flavor).
 
 rb_f_system code for VMS and Windows uses different code paths, so I don't know if it's also affected or not.
 
 I wrote a bit more about background of this issue on my blog: http://t-a-w.blogspot.com/2010/02/what-is-all-this-perl-doing-in-my-ruby.html
=end



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