A question about the at scheduler...

trist007 · 03-07-2011, 05:50 PM

Reading the man page says that it takes commands from stdin and that it uses /bin/sh to execute commands.

When I run

Code:

echo "eject" | at now + 1 minute

It doesn't run because obviously sh /usr/bin/eject will not work. /bin/sh is only for scripts not binaries. So this forces me to put the command /usr/bin/eject in a file then run sh file.

Is there any other way around that? Just curious.

trist007 · 03-07-2011, 05:59 PM

Nevermind, it's a dumb question.

Code:

echo /usr/bin/eject > script.sh;echo "sh script.sh" | at now + 1 minute

GazL · 03-07-2011, 06:30 PM

You shouldn't need to put it in a script. I would expect that first example you posted to have worked (assuming permissions and environment allowed for it)

Woodsman · 03-07-2011, 06:39 PM

Quote:

It doesn't run because...

Full path names will help avoid some problems, but your text runs fine here, exactly as you typed.

Do the commands eject and /usr/bin/eject run okay for you directly from the command line?

trist007 · 03-07-2011, 07:53 PM

Yes they do, eject is in the path and yes /usr/bin/eject works fine. But if I do

Code:

echo "/usr/bin/eject" | at now + 1 minute

it gets scheduled but never executes. Even tried

Code:

echo -n "/usr/bin/eject" | at now + 1 minute

Would the newline matter?
Yet it works if I put it in a script.
man at specifically says it uses /bin/sh to execute the command. So /bin/sh /usr/bin/eject would not work.

Richard Cranium · 03-07-2011, 08:10 PM

Code:

echo "exec /usr/bin/eject" | at now + 1 minute

Woodsman · 03-07-2011, 08:16 PM

Is the at scheduler daemon running?

ps ax | grep /usr/sbin/atd | grep -v grep

You say the job gets scheduled. Just to be sure, after executing the command, run atq to verify the command is in the at spool queue. You should see the job file in /var/spool/atjobs.

When you view the job in the spool directory you should see something like this:

Code:

#!/bin/sh
# atrun uid=1000 gid=1000
# mail slacky 0
umask 22
...
...
/usr/bin/eject

The middle of the text will be filled with environment variables.

Do you have a file at /usr/sbin/atrun?

Is /bin/sh linked to a valid shell command, such as /bin/bash?