Perl: Infinite Output

Just a little ditty … Let’s say you wanted a process to block infinitely, without using much CPU, and producing continous, non-buffered output?  Try this:

inf.pl:

#!/usr/bin/perl
my $timeout = $ARGV[0];
if ((defined $timeout) && ($timeout > 0)) {
  $timeout = time() + $timeout;
} else {
  $timeout = 0;
}
my $k = 0;
$SIG{INT} = \&caught_int;
sub caught_int {
	$SIG{INT} = 'DEFAULT';
	print "\nCaptured SIGINT.  Exiting after $k seconds.\n";
	#die;
	exit;
}
$| = 1;
while (!$timeout || (time() < $timeout)) {
	$k++;
	print "$k\n";
	sleep 1;
}

Running this program with default yields an infinite stream of numbers with output every second, until you press Control-C, like so:

$ inf.pl
1
2
3
4
5
6
7
8
9
10
11
^C
Captured SIGINT.  Exiting after 11 seconds.

If a numerical argument is provided, then output is generated for that number of seconds, and then the program exits, like so:

$ inf.pl 3
1
2
3

It’s a simple Perl script that demonstrates simple command-line argument parsing, catching Control-C (interrupts), watching the clock, and producing steady output with minimal CPU usage. … Plus, it comes in handy while testing other, more complex Perl scripts.