at

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] [-u username] [-mMlv] timespec ...
       at [-V] [-q queue] [-f file] [-u username] [-mMkv] [-t time]
       at -c job [...]
       atq [-V] [-q queue]
       at [-rd] job [...]
       atrm [-V] 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
               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 0.8, 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.

       If you specify a job to absolutely run at a specific time and date in the
       past, the job will run as soon as possible.  For example, if it is 8pm
       and you do a at 6pm today, it will run more likely at 8:05pm.

       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/bin/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.

       -u username
               Sends mail to username rather than the current 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/atd
       /var/spool/atd
       /proc/loadavg
       /var/run/utmp
       /etc/at.allow
       /etc/at.deny

SEE ALSO
       at.allow(5), at.deny(5), atd(8), cron(1), nice(1), sh(1), umask(2).

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.



                                   2009-11-14                              AT(1)