Shell Programming and Scripting

#!/usr/bin/perl
# The script is to couting time (show clock) and support Ctrl-C to pause clock
# then choose a key to continue couting or exit.

use strict 'vars';

$SIG{'INT'} = 'Pause';	# use signal handling, if press ^C, will interrupt and call sub Pause.

print "Press Ctrl-C to pause couting time \n";

our ($hour,$min,$sec) = ();
($hour,$min,$sec) = clock (0,0,0); # start couting with at 00:00:00

sub Pause {
  print "\nCaught ^C\n";
  print "Press \"c\" to continue, \"e\" to exit: ";
  while (1) {
    my $input = lc(getc());
    chomp ($input);
    if ($input eq 'c') {
      clock($hour,$min,$sec);
    }
    elsif ($input eq 'e') {
      exit 1;
    }
  }
}

# sub clock is to count time
sub clock {
  our ($hour, $min, $sec) = @_;	# declare as the global variables
  while (1) {
      sleep 1;	# get clock of system for each one second
      $sec++;
      if ($sec == 60) {
	$sec = 0;
	$min++;
	if ($min == 60) {
          $min = 0;
	  $hour++;
	  $hour = 0 if ($hour == 24)
	}
      }
      printf ("%2d:%2d:%2d\n",$hour,$min,$sec);
  }    
  return ($hour,$min,$sec);
}

C:\Program Files\Perl\mine>pause_func.pl
Press Ctrl-C to pause couting time
 0: 0: 1
 0: 0: 2
 0: 0: 3

Caught ^C
Press "c" to continue, "e" to exit: c
 0: 0: 4
 0: 0: 5

Caught ^C
Press "c" to continue, "e" to exit: e

C:\Program Files\Perl\mine>