Before every tick, get the current time, and wait whatever time is left till the next tick.

Here's a simple example. 

perl -we 'use Time::HiRes qw"time sleep"; use IO::Handle; $length = 60
+/$ARGV[0]; my $next = time; for (;;) { $next += $length; $now = time;
+ sleep($next - $now); printflush STDOUT "\a."; }' 80

[download]

Of course, this can still be inexact if the load is high (especially if the system is doing io heavily).

On the +%s thing, there's perl -we 'print time() . "\n";'.

In reply to Re: making something happen in real time by ambrus
in thread making something happen in real time by bcrowell2

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