Any Simulated Time Services?

Tim Chase blinux.list at
Sat Oct 18 04:02:36 UTC 2008

There seem to be two of syncing your system clock to 
a global time-standard and one for notifying you of the time.

For the first issue of syncing up your clock, the ntpd program 
keeps your computer clock from drifting.

For the second issue, most distros have the "at" command which 
I've found to be accurate to within about a second on my system. 
  You can do something like

   echo "/usr/bin/play /path/to/ding.wav" | at 21:15

to queue up the playing of ding.wav at 9:15:00pm.  The "at" 
command takes a fairly flexible date/time specification, and you 
can easily choose your player & wave-file.  You can use the "atq" 
("at queue") and "atrm" ("at remove") commands to view and delete 
queued jobs.  I often use this as a simple alarm-clock, 
triggering my "redalert.wav" klaxon sound to remind myself.

Remember to use the full path to the executable and .wav file 
because when they're run, they may not be run in the same 
environment as when you queued them up.

The "at" command isn't limited to just playing wave 
can look busy:

   bash$ at 21:45
   at> mail boss at -s "Working late" < /tmp/late.txt
   at> EOF

or schedule a large transfer for late at night:

   echo "wget" | at 2:00am tomorrow

or any other sort of deferred behavior you want.

As usual, the man-pages are a font of additional information.


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