If I add logic to the main program to exit the while loop before the subprogram has finished, the subprogram does not get terminated early.

use strict;
use warnings;

#1176332

my $cmd_1 = "perl 1176332p2.pl";  # (renamed from OP's hello.pl)
 
open (CMD, "$cmd_1 2>&1|") or warn ("!!! Can't run program: $!\n");
my $start = time();
printf "Started at %s\n",$start;

while (my $line = <CMD>)  {
  print "->" . $line;
  if (time() > $start + 2) {
    printf "Stopping at %d!\n",time();
    last;
  }
  if ($line =~ m/^xyz/) {
    print "\n Pretending to do some string manipulation\n";
  } else {
    print "(from $0): Nothing yet | ";
  }
}
close CMD;
printf "Actually stopped at %d\n", time();

[download]
H:\perl>perl 1176335.pl
Started at 1479848254
->Hello World from 1176332 PART 2
(from 1176335.pl): Nothing yet | ->Sleeping 10 seconds
(from 1176335.pl): Nothing yet | ->.
(from 1176335.pl): Nothing yet | ->.
(from 1176335.pl): Nothing yet | ->.
Stopping at 1479848257!
Actually stopped at 1479848264

[download]

The main program does not return control to the command line until 7 seconds later, not until the subprogram has terminated on its own.

But God demonstrates His own love toward us, in that while we were yet sinners, Christ died for us. Romans 5:8 (NASB)

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

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