Automate paired analysis - perl

Question

I have a growing number of files to process using a simple Perl script I wrote. The script takes two files as input and prints an output. I want to use a bash script (or anything really) to automate the following usage:
perl Program.pl GeneLevels_A GeneLevels_B > GeneLevels_A_B
with every paired, non-directional combination of files in a particular directory.
Here is the Perl script:
#!/usr/bin/perl
use strict;
use warnings;
die "Usage: $0 <File_1> <File_2>\n" unless #ARGV == 2;
my $file1 = shift #ARGV;
my $file2 = shift #ARGV;
my %hash1;
my %hash2;
my $counter = 0;
my $amt = 25;
my $start = 244 - $amt;
open (REF, $file1);
while (<REF>) {
my $line = $_;
chomp $line;
if ($counter < $start) {
$counter++;
next;
}
my #cells = split('\t', $line);
my $ID = $cells[2];
my $row = $cells[0];
$hash1{$ID} = $row;
$counter++;
}
close REF;
$counter = 0;
open (FILE, $file2);
while (<FILE>) {
my $line = $_;
chomp $line;
if ($counter < $start) {
$counter++;
next;
}
my #cells = split('\t', $line);
my $ID = $cells[2];
my $row = $cells[0];
$hash2{$ID} = $row;
$counter++;
}
close FILE;
while ( my ($key, $value) = each(%hash1) ) {
if ( exists $hash2{$key} ) {
print "$key\t$value\t$hash2{$key}\n";
}
}
A good solution would allow me to run the Perl script on every file with an appropriate suffix.
An even better solution would assess the suffixes of existing files to determine which pairs of files have already been processed this way and omit those. For example if File_A, File_B, File_C, and File_B_C exist then only File_A_B and File_A_C would be produced. Note that File_A_B and File_B_A are equivalent.

Answer 1

This should work. Better checks for bad arguments would be a good thing to add:
#!/bin/bash
if [ $# != 2 ]; then
echo "usage: pair <suffix1> <suffix2>"
exit
fi
suffix1=$1
suffix2=$2
for file1 in *_${suffix1}; do
fileCheck=$(echo $file1 | sed -e "s#_$suffix2##")
if [ "$fileCheck" = "$file1" ]; then
file2=${file1/_$suffix1/_$suffix2}
if [[ ( ! -f ${file1}_${suffix2} ) && ( ! -f ${file2}_${suffix1} ) ]]; then
echo processing ${file1}_${suffix2}
perl Program.pl $file1 $file2 > ${file1}_${suffix2}
fi
fi
done