$? returns the result code from the last system() call or backtick operation, I believe, so you can both capture output and process result codes.

Example:

#!/bin/perl
# first command deliberately generates an error....
print `rubbish`;
print "Rubbish Result: $?\n";
# this command should succeed
print "ls Output:\n";
print `ls -l`;
print "ls Result: $?\n";
[download]

Rubbish Result: -1
ls Output:
total 10
-rw-r--r-- 1 Userid Domain Users 1242 Oct 30 10:04 1.txt
-rw-r--r-- 1 Userid Domain Users 1531 Oct 30 10:04 2.txt
-rwxr-xr-x 1 Userid Domain Users  351 Oct 30 10:48 test.pl
-rwxr-xr-x 1 Userid Domain Users  108 Oct 31 14:21 var.pl
ls Result: 0
[download]