Perl Look behind + look ahead

Look behind:

    open(FILE,"passwd");
while($line=<FILE>)
    {
    if($line=~/(?<=lpd\:\/)bin/)
        {
        print $line."\n";
        }
    }
close(FILE);



daemon:x:1:1:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh
sys:x:3:3:sys:/dev:/bin/sh
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/bin/sh
man:x:6:12:man:/var/cache/man:/bin/sh
lp:x:7:7:lp:/var/spool/lpd:/bin/sh mail:x:8:8:mail:/var/mail:/bin/sh
news:x:9:9:news:/var/spool/news:/bin/sh


 eptuwya@JDQ08R1:~$ perl passwdple
lp:x:7:7:lp:/var/spool/lpd:/bin/sh



Look Ahead:


open(FILE,"passwd");
    while($line=<FILE>)
        {
        if($line=~/bin(?=\/sync)/)
            {
            print $line."\n";
            }
        }
close(FILE);


root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh
sys:x:3:3:sys:/dev:/bin/sh
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/bin/sh
man:x:6:12:man:/var/cache/man:/bin/sh
lp:x:7:7:lp:/var/spool/lpd:/bin/sh
mail:x:8:8:mail:/var/mail:/bin/sh
news:x:9:9:news:/var/spool/news:/bin/sh


eptuwya@JDQ08R1:~$ perl passwdplepost
sync:x:4:65534:sync:/bin:/bin/sync