Scheduling tasks in linux – the at command

I did an article a while back about cron and scheduling tasks in linux (I also mentioned kron which is a graphical interface for cron scheduling…). That works well and good for things that happen on a recurring basis, but the next question is what if I want to schedule a command (or series of commands) to happen once and not again? Well, to tell the truth I’ve used cron for this on occasion, being sure to revisit the crontab and remove the entry before it repeats again, but there is a better way. At.

I could probably do a bad vaudeville-esque bit and say “at what..”, but there is a very powerful and simple scheduler called at in linux. If you open up a command shell and want to run the command “killall mplayer” to end all running mplayer processes at 10 pm, here’s how you’d do it…..

$at 10 pm
warning: commands will be executed using (in order) a) $SHELL b) login shell c) /bin/sh
at> killall mplayer
job 12 at 2006-01-16 22:00

So, I typed “at 10 pm” (without the quotes) a the $ prompt… it gave me an interactive way of entering commands…. next I typed “killall mplayer” (and pressed enter), then since I didn’t have another command I wanted to schedule, I merely pressed ctrl-d to exit and was promptly told that the task was scheduled for 2200 hours tonight (which is 10 pm).

at can handle fairly human-friendly time scheduling…. at 5 tuesday for instance would schedule for 5 am on tuesday (today is Monday and so it schedules for tomorrow, but it is swift enough to figure that if the time has already passed for the week, then it will do it the next time it comes around.)

atq can show what’s scheduled…
$ atq
13 2006-01-17 05:00 a avery
12 2006-01-16 22:00 a avery

atrm can remove scheduled tasks…. atrm 13
atrm 12
for instance removes the above entries….

it’s also possible to feed at a file with a list of commands…. at -f listofcommands.txt
the format is usually one command per line. More information on at is available by typing “man at”
(again without the quotes) at the command line.

Related Posts

Blog Traffic Exchange Related Posts
  • Another Dumaru variant Sunbelt has found another keylogger in the dumaru family and has updated their free tool to scan for it and clean it up. This is the same family of trojans/keyloggers that contributed to the large ID theft discovery they made earlier in the month. From their post... The SSA-KeyLogger spyware......
  • Scheduling tasks in linux cron Windows has scheduled tasks which most people are only halfway aware of. Linux has very powerful scheduling capabilities coming from it's unix heritage. cron is the daemon that deals with scheduled tasks under most linux distributions. There are a couple ways that you can schedule cron tasks. The first is......
  • Evolution email error MAIL FROM command failed: Unknown Some time back, I was teetering on the brink.... I've used Evolution as my linux mail client for ages (since I switched), because it had the calender integrated etc... However, Kontact has REALLY looked nice for some time, but I didn't have time to mess with changing. Then one day,......
Blog Traffic Exchange Related Websites
  • Your Triathlon Training Schedule The most important part of your triathlon training schedule will happen in the planning phase. It is important that your plan is well thought out and the time table is well defined for your training schedule to work well. Those who are training for a triathlon must begin their training......
  • An A-Z Index of the Bash command line for Linux From   adduser Add a user to the system addgroup Add a group to the system alias Create an alias • apropos Search Help manual pages (man -k) apt-get Search for and install software packages (Debian/Ubuntu) aptitude Search for and install software packages (Debian/Ubuntu) aspell Spell Checker awk Find......
  • French Open Gets Started The French Open got underway this week with much anticipation as to what would be seen from some of the greatest players on the circuit. There were some immediate disappointments with players like Hewitt out of the French Open due to an ankle injury. Marin Cilic was eliminated early by......
PDF24    Send article as PDF   

Similar Posts

See what happened this day in history from either BBC Wikipedia
Amazon Logo

Comments are closed.

Switch to our mobile site