#!/usr/bin/perl -w
use strict;
use warnings;

print time_to_string(1234), "\n";
print time_to_string(12345), "\n";
print time_to_string(123456), "\n";

sub time_to_string {
    my $t = shift;  # t=total time in seconds

    my $seconds = $t % 60; $t=($t-$seconds)/60; # t now has minutes
    my $minutes = $t % 60; $t=($t-$minutes)/60; # t now has hours
    my $hours   = $t % 24; $t=($t-$hours)  /24; # t now has days

    my $str = '';
    $str .= "$t days, " if $t>0;
    $str .= sprintf "% 2u:% 2u:% 2u", $hours, $minutes, $seconds;
}

##</code><code>##

roboticus@Boink:~$ ./848005.pl 
 0:20:34
 3:25:45
1 days, 10:17:36
roboticus@Boink:~$