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I'm trying to schedule download at nights. I have created a atd job which starts download script at 2 AM. Now I want to stop the same job at 7 AM if it is still running. What I'm doing now is just shutdown -h 7:00. Is it possible to stop atd job at specified time?

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Stop as in kill them or pause them to be resumed later? – slm Oct 10 '13 at 20:03
@slm Does it make difference? I thought using "wget -c" will make both options look same. – Majid Azimi Oct 10 '13 at 20:06
Why not just have at run killall wget at the specified time? – terdon Oct 10 '13 at 20:11
Didn't know what exactly you were doing until you mentioned wget, so it's hard for us to say. Perhaps you could expand your Q so we know exactly what you're trying to do. Incidentally it can make a difference b/c we could just have the process go to sleep at 7AM vs. killing it and then resume later on in the day (would be one approach). – slm Oct 10 '13 at 20:15
up vote 2 down vote accepted

I don't see a mechanism within at to allow you to specify a stop time. I would just schedule another at job at 7am that would check if any of these at jobs are still running and kill them.

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At jobs are executed using a shell interpreter (on Linux, it is usually /bin/sh). It means that any command you are going to run as at job can be tracked by a PID number of the shell which is going to run that command. You can simply catch this PID with special shell variable $$. You can save it to a file (single quotes are mandatory to not expand it in your current session shell):

at 'echo $$ > /var/run/my_at_job.pid; your_command; rm /var/run/my_at_jon.pid' | at TIME_SPEC

and later, in another at job, you can kill the job and all its spawned child processes (you_command):

if [ -r /var/run/at_job.pid ]; then
  for PID in $(ps --ppid `cat /var/run/at_job.pid` -o pid | sed -e '1d'); do
    kill $PID
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You could incorporate the timeout into your job.

timeout "$(($(date +%s -d '7am') - $(date +%s)))" wget -c http://example.com/wibble

Alternatively, have your job write its process ID somewhere so that you can kill it. In the 2am job:

echo $$ >~/.at.download.pid
wget -c http://example.com/wibble
rm ~/.at.download.pid

In the 7am job:

if [ -e ~/.at.download.pid ]; then
  kill $(~/.at.download.pid)
  rm ~/.at.download.pid
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