Then you'll notice that in some places you've used $input2 and some places $input_file2 (I'm guessing you probably want the latter, to match the other variables).

Here's what I've done to get rid of all the warnings, in most cases merely adding my to your variables to make them lexically scoped:

use File::Copy;
use Tie::File;

use strict;
use warnings;

my($input_file1) = $ARGV[0];
my($input_file2) = $ARGV[1];
my($output_file) = $ARGV[2];

if ( !defined($input_file1) || !defined($input_file2) || !defined($out
+put_file) ) {
    print "Error: usage: ./SS7Merge input_file1 input_file2 output_fil
+e\n";
}
else {
    # -----Backup the input files in case of error-----
    copy( $input_file1, $input_file1 . ".bak" ) or
        die "Could not backup file 1 $input_file1 to $input_file1.bak:
+ $!\n";
    copy( $input_file2, $input_file2 . ".bak" ) or
        die "Could not backup file 2 $input_file2 to $input_file2.bak:
+ $!\n";

    # -----Attempt to open all of the files-----
    open( INFILE1, $input_file1 ) || die( "Could not read input file 1
+ ($input_file1): $!" );
    open( OUTPUT, "> " . $output_file ) || die( "Could not open output
+ file ($output_file): $!" );

# We are going to read file2 into an array. The file will not be loade
+d into memory which will improve processing of large files.

use FileHandle;
my $fh = new FileHandle;
my @input_file2;
tie @input_file2, 'Tie::File', \$fh, or die "Problem tying file $input
+_file2: $!"; 

while (<INFILE1>) {
        my $line = $_;
        chomp($line);

        # -----A line starting with a '2' is a header and is left unch
+anged
        if ( $line !~ m/^2/ ) {

            foreach my $line2 (@input_file2) {
                my $date = substr( $line, 6, 6 );
                my $number_dialed = substr( $line, 29, 10 );

                if ( index( $line2, $date ) != -1 and index( $line2, $
+number_dialed ) != -1 ) {
                    my $record_type = substr( $line, 5, 2 );

                    # -----From File2-----
                    my $carrier_info = substr( $line2, 44, 5 );
                    my $destination_number = substr( $line2, 122, 10 )
+;

                    my $connect_time = substr( $line, 54, 6 );
                    my $send_to_OCN = substr( $line, 186, 4 );

                    $record_type = "25";
                    $send_to_OCN = "2604";

                    #-----Generate the output string-----
                    my $output_line = substr( $line, 0, 4 ) . $record_
+type . $date . substr( $line, 12, 17 )
                        . $number_dialed . substr( $line, 39, 5 )
                        . $carrier_info . substr( $line, 49, 5 )
                        . $connect_time . substr( $line, 60, 62 )
                        . $destination_number . substr( $line, 132, 54
+ )
                        . $send_to_OCN . substr( $line, 190, 20 ) . "\
+n";

#                    -----Debug code. Add in if you are experiencing p
+roblems-----
#                    print OUTPUT $output_line;
#                    print STDOUT "Output " . ++$outputcount . "\n";

                    last;
                }
            }
        }
        else {
            print OUTPUT $line . "\n";
        }
    }
# Untie the array before closing the file use

    untie @input_file2;

# -----Close all of the files-----
    close( INFILE1 );
    close( OUTPUT );
}
[download]

Hopefully that will get you farther...

Thank you liverpole. I was just reading about using "my" and your post confirmed this is what I ought to do. My useage of tie::file seems to be the only thing holding back this script now. The only error I now get is this:

usage: tie @array, Tie::File, filename, [option => value]... at ./SS7Merge line 42

Thanks again,
Stephen

use FileHandle;
my $fh = new FileHandle;
my @input_file2;
tie @input_file2, 'Tie::File', \$fh, or die "Problem tying file $input
+_file2: $!";
[download]

... gives...

usage: tie @array, Tie::File, filename, [option => value]... at ./SS7M
+erge line 42
[download]

What's all that stuff with $fh? You appear to be trying to pass Tie::File a reference to a reference to (sic) a GLOB when all it really wants is a filename.

Surely you just meant...

tie my @input_file2, 'Tie::File', $input_file2
   or die "Problem tying file $input_file2: $!";
[download]

You can pass 'Tie::File' a filehandle (aka a reference to a GLOB not a reference to a reference to a GLOB) but you'd need open it first.

open my $fh, '+<', $input_file2
  or die "Problem opening file $input_file2: $!";
tie my @input_file2, 'Tie::File', $fh
  or die "Problem tying file $input_file2: $!";
[download]

Note, the FileHandle module was long ago superceeded by the IO::* modules (particularly IO::File and IO::Handle) but you rarely need to construct them explicitly.