AT(1)							      General Commands Manual							     AT(1)

NAME

       at, batch, atq, atrm - queue, examine or delete jobs for later execution

SYNOPSIS

       at [-V] [-q queue] [-f file] [-mldv] timespec...
       at [-V] [-q queue] [-f file] [-mkdv] [-t time]
       at -c job [job...]
       atq [-V] [-q queue]
       atrm [-V] job [job...]
       batch
       at -b

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 out-
	       put 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 spe-
       cific 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 exact 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.

       If the file /etc/at.allow exists, only usernames mentioned in it are allowed to use at.

       If /etc/at.allow does not exist, /etc/at.deny is checked, every username not mentioned in it is then allowed to use at.

       If neither exists, only the superuser is allowed use of at.

       An empty /etc/at.deny means that every user is allowed use these commands, this is the default configuration.

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 spe-
	       cial 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.

       -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.

       -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

SEE ALSO

       cron(1), nice(1), sh(1), umask(2), atd(8).

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.

AUTHOR

       At was mostly written by Thomas Koenig, ig25@rz.uni-karlsruhe.de.

								    2009-11-14								     AT(1)