Shell Programming and Scripting

awk -F: 'FNR==NR { 
              users[$2]
              next
         } 
         !( $1 in users ) { print $1 }' <userfile> /etc/passwd

#!/usr/bin/perl
use strict;
use warnings;

my @pins;
open (PIN_FILE, "< pinfile")  or  die "Failed to read file pinfile : $!";
while (my $line = <PIN_FILE>) {
    push (@pins, (split (/:/, $line))[0]);
}
close (PIN_FILE);

open (PASS_FILE, "< /etc/passwd")  or  die "Failed to read /etc/passwd file : $! ";
while (my $pass_line = <PASS_FILE>) {
    my $uid = (split (/:/, $pass_line))[2];
    my $found = "no";
    foreach my $pin (@pins) {
        if ($pin eq $uid) {
            $found = "yes";
            last;  # this id is found, so stop searching further
        }
    }
    if ($found eq "no") {
        print "$uid is not found in pinfile \n $pass_line \n\n";
    }
}
close (PASS_FILE);

>cat passwordfile
pin:userid:comments:
9876:clooneyg:"George Clooney,Los Angeles CA,123-123-1234":
1652:simpsonh:"Homer Simpson,Los Angeles CA,123-123-1234":

>cat userfile
pin:userid:comments:
1234:pittb:"Brad Pitt,Los Angeles CA,123-123-1234":
9876:clooneyg:"George Clooney,Los Angeles CA,123-123-1234":
6548:dansont:"Ted Danson,Los Angeles CA,123-123-1234":
9685:owenc:"Clive Owen,Los Angeles CA,123-123-1234":
1652:simpsonh:"Homer Simpson,Los Angeles CA,123-123-1234":

awk -F":" 'BEGIN{ while(getline < "passwordfile") { arr[$2]=i++ } }{ for ( i in arr ) { if ( i == $2 ) { cnt=1} } if ( cnt != 1 ) { print } cnt=0; }' userfile

1234:pittb:"Brad Pitt,Los Angeles CA,123-123-1234":
6548:dansont:"Ted Danson,Los Angeles CA,123-123-1234":
9685:owenc:"Clive Owen,Los Angeles CA,123-123-1234":