use IO::Select qw( ); my $sel = IO::Select->new(\*STDIN, \*TNIN); my %bufs; MAIN_LOOP: while (my @ready = $sel->can_read()) { for my $fh (@ready) { our $buf; local *buf = \$bufs{$fh}; # Alias my $bytes_read = sysread($fh, $buf, 4096, length($buf)) or last MAIN_LOOP; my $line_end = index($buf, $/); next if $line_end < 0; my $line = substr($buf, 0, $line_end+1, ''); if ($fh == \*STDIN) { print TNOUT do_this($line); } else { print STDOUT do_that($line); } } }