open(PS, "ps -ef |") or die "Problem invoking 'ps': $!\n";
while (<PS>) {
  next unless /$version/ && /online/;
  my($pid) = (split)[2];
  print "pid $pid\n";
}
close(PS);
[download]

Cheers,
Matt

P.S. If you want to access the value of $pid outside of the while loop, drop the 'my' but keep the parens, but that will break if there's more than one match:

while (<PS>) {
  next unless /$version/ && /online/;
  ($pid) = (split)[2];
}
print "pid $pid\n";
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The return value of system is the exit code of the command run. If you want to capture STDOUT from the command, you should use `` (Backticks), or qx//;.

You could also look at using a CPAN module: Proc::ProcessTable. While not perfect, it does a good job on most flavors of *nix.

Most likely, Perl interpolates the $2 in your awk invocation. I test Perl scripts that call other programs by printing out the command line and comparing that to my expectations:

my $command = "ps -ef | grep $version | grep online| awk '{print $2}'"
+;
print "Invoking: >>>$command<<<\n";
my $output = `$command`;
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Most likely, the output you will see above is not what you want, and you want instead something like:

my $command = sprintf q(ps -ef | grep %s | grep online| awk '{print $2
+}'), $version;
print "Invoking: >>>$command<<<\n";
my $output = `$command`;
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which circumvents the interpolation of variables. There are many other ways to build up $command without interpolating variables.

Update: Reading JediWizards reply, I realize you're using system - if you want the output of commands, don't use system, use backticks, just like in the shell.

@proc = `ps -ef | grep $param`;
foreach $proc(@proc){
  ($userid, $pid, @rest) = split(' ', $proc);
  print "$userid $pid\n";
}
[download]