my @files = map { IO::File->new($_->[0], $_->[1]) || die $! } ([shift, 'r'], [shift, 'w']); $files[1]->print( sort $files[0]->getlines ); $_->close for @files;
use autodie; open my $out, '>', $ARGV[1]; print {$out} sort do {open my $in, '<', $ARGV[0]; <$in>};