use strict;
use warnings;

my $outFile = 'extractedData.txt';
my @sampleLines;

for my $file ( grep !/^\Q$outFile\E$/, <*.txt> ) {
	open my $fh, '<', $file or die $!;

	# Get data from file...
	push @sampleLines, $data;

	close $fh;
}

open my $outFH, '>', $outFile or die $!;
print $outFH @sampleLines;
close $outFH