use Gtk2 '-init'; use Gtk2::Helper; use Glib qw/TRUE FALSE/; use IO::Handle; my $cmd = [perl => -e => '$|++; for my $i (0..4) { $sum+= $i; print "Line $i: sum = $sum\r"; sleep 1;}']; my $cb = sub {print "CB: >>" . shift() . "<<\n";}; open(my $fh, '-|', @$cmd) or die "failed to launch external command: $!"; $fh->blocking(0); $tag = Gtk2::Helper->add_watch($fh->fileno, in => sub { if ($fh->eof) { print "pipe EOF\n"; Gtk2::Helper->remove_watch($tag); close $fh; return; } while (1) { my $buf; $fh->sysread($buf, 4095); print "READ: >>$buf<<\n"; last unless $buf; for (split(/[\r\n]/, $buf)) { $cb->($_); } } # keep watch active return TRUE; }); Gtk2->main;