Anyways, you should probably keep in mind, that you're about to write a fork bomb.

I see what you mean. Original code (not published here) had a check for that (see below) which is executed in the loop as launch(@ARGV). And if a Bash script should run periodically, we have a special Bash script to check if only one instance of a particular script is running. Although I must say, we are currently in the middle of porting of the Bash scripts to Perl.

sub launch {
    return if fork;
    exec @_;
    die "Couldn't exec";
}

$SIG{CHLD} = 'IGNORE';
[download]

For Perl scripts, we use the Highlander function to eliminate the forks. This, however, could effectively kill the processes we want to run each second (n seconds), when one instance is running longer that the period.

And generally, we need n * second intervals. Some scripts run each second, others every 5 seconds. I have created this question to find a way to run the scripts every n seconds most accurately.

Beside of this, I guess, best way for really exact timing would be spawning the script, which now wait's within a spinlock for the current second to change.

This is interesting to me, but I am not a Perl guru (not even a pro programmer), therefore I’d like to ask you for more info what exactly is the spawning and the spinlock (although for this I should open another question I think). Thanks. :)

You also don't write, which platform you're on.

We run the scripts (and Perl) on CentOS exclusively. No need for portability.