chomp($phi = `ls slk`);
chomp($phi2 = `ls *.csv`);
open(OUT,"> /home/Aug18.csv") or die "Cannot open output file;
open(READDATA, "< /home/$phi") or die "Cannot Open file;

##</code><code>##

@phi2 = `ls *.csv`;
chomp @phi2;  # chomp will apply to every element of the array

##</code><code>##

  your_script.pl  slk  someinput.csv > /home/Aug18.csv

##</code><code>##

#!/usr/bin/perl -w

use strict;

die "Usage: $0 infile1 infile2\n" unless (@ARGV==2 and -f $ARGV[0]);
my ($infile1, $infile2) = @ARGV;
open( READDATA, $infile1 ) or die "Cannot open $infile1: $!\n";

my %h = ();
while (<READDATA>)
{
    if ( /(\d{4}\w\d?)\s+(\w*)/ ){
        my ( $port, $lsn ) = ( $1, $2 );
        $h{$port} = $lsn;
    }
}
close READDATA;

open( READDATA2, $infile2 ) or die "Cannot open $infile2: $!\n";
while (<READDATA2>)
{
    chomp;
    if ( /(\d{4}\w\d?)/ and exists( $h{$1} )) {
        print "$_,$h{$1}\n";
    }
}