#!/usr/bin/perl

alarm 3;  # have the OS send myself a SIGALRM after 3 seconds

for (1..100) {
    print "sending line $_\n";
    select undef, undef, undef, 0.5;
}
print "Done.\n";

##</code><code>##

$ ./887855.pl
sending line 1
sending line 2
sending line 3
sending line 4
sending line 5
sending line 6
sending line 7
Alarm clock