#! perl
use strict;
use warnings;

my $file = 'passwd';

open(my $fh, '<', $file) or die "Cannot open file '$file' for reading: $!";

# The while loop reads one line of the data file at a time by implicitly
# splitting on newlines. So, on the first iteration, $line =
# bsulli03:*:32452:5002:barry sullivan,l230,555-6666,:/students/bsulli03:/usr/bin/ksh

while (my $line = <$fh>)
{
    chomp $line;    # Remove the trailing newline

    # Split the line on the colon character. On the first loop iteration,
    # @fields = ('bsulli03',                        # $fields[0]
    #            '*',                               # $fields[1]
    #            '32452',                           # $fields[2]
    #            '5002',                            # $fields[3]
    #            'barry sullivan,l230,555-6666,',   # $fields[4]
    #            '/students/bsulli03',              # $fields[5]
    #            '/usr/bin/ksh');                   # $fields[6]
    # (Note that array indexes start at zero.)

    my @fields = split /:/, $line;

    # Now split the fifth field (index 4) on the comma character. On the first
    # loop iteration, @names = ('barry sullivan', 'l230', '555-6666');

    my @names  = split /,/, $fields[4];

    # Now split the first field (index 0) on the space character. On the first
    # loop iteration, @first = ('barry', 'sullivan');

    my @first  = split / /, $names [0];

    # Print the first name, which on the first loop iteration is 'barry'

    print "$first[0]\n";
}

close $fh or die "Cannot close file '$file': $!";