Good advice. Security can also be improved by using the safer "flavor" of system. If you pass system a string, it will use a sub-shell to figure out what that string means. This can easily be abused and is almost always overkill anyway.

It's safer to pass system a list. The first element will be treated as the program name to fork, the rest are params to said program. Perhaps a concrete example is best: 

#!/usr/bin/perl -w
use strict;

# malicious input
my $dir = '/tmp; echo "GOT YA"';

# system using shell
print "AS STRING\n";
system("ls $dir");

# system w/o the shell
print "\nAS LIST\n";
system('ls', $dir);

=OUTPUT
AS STRING
  [snip -- same as `ls /tmp`]
GOT YA

AS LIST
 ls: /tmp; echo "GOT YA": No such file or directory

[download]
Notice how 'ls /tmp; echo "GOT YA"' is parsed into two separate commands by the shell. By calling system in a safer way we can force everything in $dir to be treated as a filename.

-Blake

In reply to Re: Apple, quoting, and system() by blakem
in thread Apple, quoting, and system() by Masem

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