Shell Programming and Scripting

#!/usr/bin/perl

use warnings;
use strict;

my @array = ();

### Load file into array
for my $i (split '\n', `more file1`) {
    push @array, [ split ',', $i ] ;
}


### Define valid prefix
my @prefix_list=qw(07774 888493 777);

### Create loop for each line
LINE: for (my $line=0; $line<=$#array; $line++) {
    
    ### Print first part of each line.
    print "$array[$line][0],";

    ### Create loop for each prefix
    PREFIX: for my $prefix (@prefix_list) {
        
        ### Find length of prefix
        my $prefix_lngth = length $prefix;

        ### Check the second column in the line for a prefix match
        if (substr($array[$line][1], 0, $prefix_lngth) =~ /$prefix/) {

            ### If the prefix is found, print the prefix and then the rest of the line using substr
            print substr($array[$line][1], 0, $prefix_lngth), ",", substr($array[$line][1], $prefix_lngth), "\n";

            ### Jump to the next line now that you've parsed the entire line
            next LINE;
        }
    }

    ### If the prefixes don't match, just print second column
    print ",$array[$line][1]\n"
}