at
rm queue, examine or delete jobs for later execution
see also :
batch - atq - atrm - atd - cron - nice - sh
Synopsis
at
[-V] [-q queue] [-f file]
[-mMlv] timespec...
at [-V] [-q queue] [-f
file] [-mMkv] [-t time]
at -c job [job...]
atq [-V] [-q queue]
at [-rd] job [job...]
atrm [-V] job [job...]
batch
at -b
add an example, a script, a trick and tips
examples
source
Linux at command with seconds precision
Use cron to run a script that calls the sleep
command for the sub-miniute precision bit of it? So
sleep 10 ; foo.sh
should run foo.sh 10 seconds after the command is
called.
source
Getting zenity and at to work properly
Check your /var/log/messages, chances are you'll
have some "Cannot open display" errors from your X Server.
You need to provide utilities like at and
cron access to your X Display by name. Edit your
~/.bashrc to include the following:
xhost local:USERNAME > /dev/null
Substitute your username for the USERNAME value
above. This will provide the at utility with the
name of your X Display so it can attempt to fork zenity on it.
Modify your zenity command to include the --display
switch:
echo "zenity --info --display=:0.0" | at now + 1 min
source
How can at execute a command from the command line
at read the command from standard input (or a file
if you specify it with -f).
This should work:
echo 'find /path -name "pattern" > output.lst' | at now +X minutes
source
How to list all 'at' jobs without root privileges?
This may not be the answer you want, but strictly speaking, you
could boot a Live CD and use that to look at the files in
/var/spool/at (or equivalent).
The privacy and security provisions of Unix/Linux does not allow
you to do what you want. The at files are stored by default with
"other" read privilege set to off.
source
'at' command output on Mac
That is because you're echoing the output of $ at
08.00 into at_output.txt.
Try this instead.
$ at 08:00
./VM-run.sh > at_output.txt
^D
Then you'll get a confirmation like this.
job 1 at Sat Sep 24 08:00:00 2011
Edit: Alternatively for shell scripts, you can
restructure the command like this.
#!/bin/bash
./VM-run.sh > at_output.txt | at 08:00
source
Have the at command return the job id of the task just submitted
Assuming that the job you want to run is in a file called
test.sh, the following will return the id:
$ at now -f test.sh 2>&1 | grep job | awk '{print $2}'
8
The 2>&1 redirects stderr to stdout so you
can manipulate it. The grep gets the job line. The
awk returns the second field in the line found by
grep, which contains the job id.
So it get it into a variable, you can do:
$ TEST=`at now -f test.sh 2>&1 | grep job | awk '{print $2}'`
$ echo $TEST
9
source
Linux 'at' command history
On my system I can find the list at /var/log/cron/*.
You might look for something similar.
source
How configure email the at/batch results is sent to?
I don't see a way of doing that in the at invocation, but you
could probably do something like this with the command you're
calling via at:
$ at 16:00
at> some-command [arguments, &c.] 2>&1 | sendmail [-f <from-address>] <recipient>
at> ^D
When the command runs, it will hand off its output to sendmail
for delivery to the specified recipient, and in the quick test
I've just run, this does work.
Of course, if you're already redirecting the output from
some-command to go somewhere else, you might be out of luck --
but, then, you could always tee(1) the output, or add a final
line to the at job calling sendmail to push out the message.
source
Puzzle of atrm vs at -d
Program code can know what the name of the executable was that
launched it. It's possible that the at program does
something like this:
if (my name is 'atrm') then
add '-d' parmeter
end
do stuff like regular 'at' program.
description
at and
batch read commands from standard input or a
specified file which are to be executed at a later time,
using /bin/sh.
at
executes commands at a specified time.
atq
lists the user’s pending jobs, unless the user is
the superuser; in that case, everybody’s jobs are
listed. The format of the output lines (one for each job)
is: Job number, date, hour, queue, and username.
atrm
deletes jobs, identified by their job number.
batch
executes commands when system load levels permit; in
other words, when the load average drops below 1.5, or the
value specified in the invocation of atd.
At
allows fairly complex time specifications, extending the
POSIX.2 standard. It accepts times of the form HH:MM
to run a job at a specific time of day. (If that time is
already past, the next day is assumed.) You may also specify
midnight, noon, or teatime (4pm) and you can
have a time-of-day suffixed with AM or PM for
running in the morning or the evening. You can also say what
day the job will be run, by giving a date in the form
month-name day with an optional year, or
giving a date of the form MMDD[CC]YY,
MM/DD/[CC]YY,
DD.MM.[CC]YY or
[CC]YY-MM-DD. The specification
of a date must follow the specification of the time
of day. You can also give times like now + count
time-units, where the time-units can be minutes,
hours, days, or weeks and you can tell at
to run the job today by suffixing the time with today
and to run the job tomorrow by suffixing the time with
tomorrow.
For example, to
run a job at 4pm three days from now, you would do at 4pm
+ 3 days, to run a job at 10:00am on July 31, you would
do at 10am Jul 31 and to run a job at 1am tomorrow,
you would do at 1am tomorrow.
The definition
of the time specification can be found in
/usr/share/doc/at/timespec.
For both
at and batch, commands are read from standard
input or the file specified with the -f option and
executed. The working directory, the environment (except for
the variables BASH_VERSINFO, DISPLAY,
EUID, GROUPS, SHELLOPTS, TERM,
UID, and _) and the umask are retained from
the time of invocation.
As at is
currently implemented as a setuid program, other environment
variables (e.g. LD_LIBRARY_PATH or LD_PRELOAD)
are also not exported. This may change in the future. As a
workaround, set these variables explicitly in your job.
An at
- or batch - command invoked from a
su(1) shell will retain the current userid. The user
will be mailed standard error and standard output from his
commands, if any. Mail will be sent using the command
/usr/sbin/sendmail. If at is executed from a
su(1) shell, the owner of the login shell will
receive the mail.
The superuser
may use these commands in any case. For other users,
permission to use at is determined by the files
/etc/at.allow and /etc/at.deny. See
at.allow(5) for details.
options
-V
prints the version number to
standard error and exit successfully.
-q
queue
uses the specified queue. A
queue designation consists of a single letter; valid queue
designations range from a to z and A to
Z. The a queue is the default for at
and the b queue for batch. Queues with higher
letters run with increased niceness. The special queue
"=" is reserved for jobs which are currently
running.
If a job is
submitted to a queue designated with an uppercase letter,
the job is treated as if it were submitted to batch at the
time of the job. Once the time is reached, the batch
processing rules with respect to load average apply. If
atq is given a specific queue, it will only show jobs
pending in that queue.
-m
Send mail to the user when the job has completed even if
there was no output.
-M
Never send mail to the user.
-f file
Reads the job from file rather than standard
input.
-t time
run the job at time, given in the format
[[CC]YY]MMDDhhmm[.ss]
-l
Is an alias for atq.
-r
Is an alias for atrm.
-d
Is an alias for atrm.
-b
is an alias for batch.
-v
Shows the time the job will be executed before reading
the job.
Times displayed
will be in the format "Thu Feb 20 14:50:00
1997".
-c
cats the jobs listed on the
command line to standard output.
files
/var/spool/cron/atjobs
/var/spool/cron/atspool
/proc/loadavg
/var/run/utmp
/etc/at.allow
/etc/at.deny
bugs
The correct
operation of batch for Linux depends on the presence
of a proc- type directory mounted on
/proc.
If the file
/var/run/utmp is not available or corrupted, or if
the user is not logged on at the time at is invoked,
the mail is sent to the userid found in the environment
variable LOGNAME. If that is undefined or empty, the
current userid is assumed.
At and
batch as presently implemented are not suitable when
users are competing for resources. If this is the case for
your site, you might want to consider another batch system,
such as nqs.
see also
at.allow,
at.deny, atd , cron ,
nice , sh , umask.
author
At was mostly
written by Thomas Koenig, ig25[:at:]rz[:dot:]uni-karlsruhe.de.