First off this is dangerous - or at least can be. Whatever you do make sure that you are not passing values to the command line that could be passed to the CGI program without doing some serious checking of the values.

Next is that by default anything executed by a CGI program is going to be run as user nobody (or some rather anonymous and less powerful user). There is good documentation at Apache's web site that can help you set up scripts to run SUID. Basically as whatever user you want. Again this is dangerous - the whole point of a nobody user is that they cannot do as much damage.

Now, it's hard to tell your level of experience from your question, but a few things you should know in general about CGI coding (and even more generally about Perl coding). You want to specify use strict; at the top of your code and use CGI; since this is a CGI program. Using strict forces some good coding habits upon you. Using CGI protects you in other ways - like some basic taint checking from your incoming request.

From here executing system commands is easy if you have the rest of your script working properly. The following (untested) snippit sets up a CGI object then upon receiving a certain value from the user executes a system command:

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

my $q = new CGI;
my @result;

# other stuff happens

if ($q->param('command') eq "command1")
{
    # Notice how I pass NOTHING to the
    # system command that was handed to 
    # the CGI script.
    @result = `/usr/local/bin/script.sh`;
}
elsif ($q->param('command') eq "command2")
{
    # command 2...
}
#  more stuff happens.

# Include code to render your html around here
# then display the result of your system command here:
print join "<BR>", @result;
# Close out your html document.
[download]

Good luck,

{NULE}
--
http://www.nule.org

We need more information. Is it a daemon process which must live after the cgi process is gone? Does it exit with a return code you must check? Do you need to capture the processeses ouput? Each of these is done differently.

The perlfunc manpage has a useful introduction which lists functions by category. "Processes and Process Groups" is a good start.

Update: tid, I wrote a node on starting a daemon process at Re: Daemons???. Your daemon is probably dying because it hasn't made itself a process group leader before the parent exits. It is then inherited by init, which ruthlessly kills widows and orphans. 2: You may want to arrange for your daemon to restart or reread config on, say, SIGHUP. Then kill 'HUP', $pid; would suffice.

After Compline,
Zaxo

Jason