#! usr/bin/perl
use strict;
use warnings;

# length of end-of-line marker
my $eol_len = length $/;

opendir my $dh, "." or die "Can't open current directory: $!\n";

while( my ( $file ) = readdir $dh ) {
	next if $file !~ /\.txt/;

	open my $fh, '+<', $file
		or warn( "Can't open $file for read/write: $!\n" ), next;

	# read data from last possible location of end-of-line
	seek $fh, -$eol_len, 2;
	my $tail = <$fh>;

	# if chomp finds an EOL, rewind and truncate
	if( chomp $tail ) {
		seek $fh, -$eol_len, 2;
		truncate $fh, tell $fh;
	}
}