From: JJ <jjnoakes@...>
Date: 2008-01-07T05:14:59+09:00
Subject: Ruby's Kernel::exec (and system and %x)

I was reading about Kernel::exec (and the related Kernel::system
function and %x operator).

These routines follow the Perl-ish idiom, which is "If there is one
argument, pass it to the shell; if there is more than one argument,
execute it directly". I call it the Perl-ish idiom simply because that
is the first place I saw this one-exec-routine-to-serve-them-all
behavior.

Now, there is a serious limitation to this, which exists on all
platforms that allow shell meta-characters in file names (space,
asterisk, etc). I usually come across the bug when running
applications on Windows. The problem is this:

  exec("C:\\Program Files\\Anything\\Foo.exe");

Since this is a one-argument call to Kernel::exec, Ruby passes it to
the command interpreter, which tries to split the single argument on
shell meta-characters as it would for "echo *" or "ls -al". However,
"C:\\Program" is not the executable that we desire.

In Perl, one can force the no-shell-interpreter path by calling exec
(and system) like so:

  my $cmd = "C:\\Program Files\\...";
  exec( { $cmd } $cmd );

Is there any such option in Ruby?

-JJ