http://qs1969.pair.com?node_id=1176357


in reply to Re^2: Run and kill external programm after x seconds
in thread Run and kill external programm after x seconds

Apologies. Here's a version that eliminates much of the extra stuff, and adds a bunch of comments:

#!/usr/bin/env perl use strict; use warnings; use Time::HiRes qw(usleep); use IO::Select; use File::Spec::Functions qw(catfile); use constant USLEEP_TIME => 25_000; # Microseconds use constant RUN_TIME => 30; # Seconds my $cmd = catfile((getpwnam($ENV{USER}))[7],'scripts','outputter'); # +This just sets up the path to the external script. print "Our command is >>>$cmd<<<\n"; open my $r, '-|', $cmd or die $!; # Open a pipe to read output f +rom a command. my $s = IO::Select->new($r); # Create an IO::Select object +on our pipe's filehandle, $r. my $pinged = 0; # Poor-man's messaging: We hav +en't received a ping yet. my $start = time(); # Record our start time so we +can calculate when to exit. while(time() < $start + RUN_TIME) { # Iterate until we run out of +time. if ($r->eof) { # Finish if the target command + has finished all output and termianted. last; } elsif ($s->can_read(0)) { # See if there's something + available to read. chomp(my $i = <$r>); # Read from our pipe and c +homp. print "\n<$i>\n"; # Print what we read. $pinged = 1 if $i eq 'ping'; # Send a message that we r +ead something. } elsif ($pinged) { # If we have a ping messag +e, print a pong. print "(pong)\n"; $pinged = 0; # And unset the message. } else { usleep USLEEP_TIME; # If there's nothing to do +, sleep briefly. print '.'; # Print something to let e +veryone know we're thinking of them. STDOUT->flush; } } # lather, rinse, repeat.

Again, the "outputter" script (terribly named) should be:

#!/usr/bin/env perl use strict; use warnings; use IO::Handle; STDOUT->autoflush(1); while (1) { print STDOUT "ping\n"; sleep 2; }

The output is going to look approximately like this:

Our command is >>>/home/......./scripts/outputter<<< ...................................................................... +.......... <ping> (pong) ...................................................................... +.......... <ping> (pong) .................................^C Command terminated

If I had let it run long enough it would time out and exit cleanly.


Dave