my $EA_Mac_Counter = 0; 
until ($EA_Mac =~ /^(a|b|c|d|e|f|A|B|C|D|E|F|0|1|2|3|4|5|6|7|8|9){12}$/)        #Checks for a valid Polycom MAC 
{ 
        if ($EA_Mac_Counter < 1) 
        { 
                print "Please enter the MAC address of the Executive Assistant: ";  #Executive Assistant input 
        } 
 
 
        elsif ($EA_Mac_Counter > 2) 
        { 
                print "You have entered an invalid MAC address too many times!   Script is closing....\n"; 
                exit; 
        } 
 
        else 
        { 
                print "The MAC address you entered is invalid!  Please enter again: "; 
        } 
 
        chomp($EA_Mac=<STDIN>); #This chomps the data for the if statement and the else statement. 
        $EA_Mac = lc($EA_Mac); #Converts MAC address to lower case 
        $EA_Mac_Counter++; 
} 
 
print "How many users are being monitored? ";  #Amount of monitored users input 
chomp($Mon_User_Count=<STDIN>); 
 
print "Please enter the first and last name of monitored user: ";  #Monitored user name input 
chomp($Mon_UserName=<STDIN>);

my @Mon_UserName; 
 
for my $i (1..$Mon_User_Count) { 
    print "Please enter the first and last name of monitored user: "; 
    chomp($Mon_UserName[$i-1]=<STDIN>); 
}

$Mon_UserName[1]

for my $Mon_UserName_Loop (1..$Mon_User_Count) 
{ 
        print "Please enter the first and last name of monitored user: ";  #Monitored user name input 
        chomp($Mon_UserName[$Mon_UserName_Loop-1]=<STDIN>);     #Access proper Array Index 
} 
 
 
my $UserMac_Counter = 0; 
for my $Mon_UserMac_Loop (1..$Mon_User_Count) 
{ 
        until ($Mon_UserMac[$UserMac_Counter] =~ /^(a|b|c|d|e|f|A|B|C|D|E|F|0|1|2|3|4|5|6|7|8|9){12}$/) 
        { 
 
                if ($UserMac_Counter < 1) 
                { 
                        print "Please enter the MAC address of $Mon_UserName[$UserMac_Counter]: ";  #Monitored user MAC input 
                } 
 
                elsif ($UserMac_Counter > 2) 
                { 
                        print "You have entered an invalid MAC address too many times!   Script is closing....\n"; 
                        exit; 
                } 
 
                else 
                { 
                        print "The MAC address you entered is invalid!  Please enter again: "; 
                } 
 
                chomp($Mon_UserMac[$Mon_UserMac_Loop-1]=<STDIN>); 
                #$Mon_UserMac = lc($Mon_UserMac); #Converts MAC Address to lower case 
                $UserMac_Counter++; 
        } 
}

/^[abcdef\d]{12}$/i

#!/usr/bin/perl  
use strict; 
use warnings; 
 
print "Enter nr of users: "; 
my $nr = <>; 
 
my @a; 
 
for (1 .. $nr) { 
    print "Enter name of user nr $_\n"; 
    my $name = <>; 
    chomp $name; 
    push @a, $name; 
} 
 
# pieces of the MAC regex 
my $d = "[0-9A-Fa-f]"; 
my $dd = "$d$d"; 
 
my $max_tries = 3; 
 
for my $i ( 0 .. $#a ) { 
    my $tries = 0; 
    LOOP: { 
        print "Enter MAC address for user $a[$i]\n"; 
        my $mac = <>; 
        chomp $mac; 
 
        if ( $mac =~ /^$dd([:;-])$dd(\1$dd){4}$/ ) { 
            print "$a[$i] has MAC $mac\n"; 
        } 
        else { 
            $tries++; 
            if ( $tries < $max_tries ) { 
                print "False MAC, try again.\n"; 
                redo LOOP; 
            } 
            else { 
                print "Too many false tries. Bye.\n"; 
                exit; 
            } 
        } 
    } 
}

open my $fh, '<', "/path/to/$mac.cfg" or die $!; 
my @cfg = <$fh>; 
for my $line ( @cfg ) { 
    # do stuff with $line 
} 
close $fh;

open my $fh, '<', "/path/to/$mac.cfg" or die $!; 
while (<$fh>) { 
    # each line is now in $_, do stuff with that 
} 
close $fh;

for my $i ( 0 .. $#a ) {