at

AT(1)                       General Commands Manual                      AT(1)

NAME
       at,  batch, atq, atrm - queue, examine, or delete jobs for later execu-
       tion

SYNOPSIS
       at [-V] [-q queue] [-f file] [-mMlv] timespec ...
       at [-V] [-q queue] [-f file] [-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 supe-
               ruser; 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 spe-
       cific time of day.  (If that time is already past, the next day is  as-
       sumed.)   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  morn-
       ing  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 giv-
       ing  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  specifica-
       tion  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 to-
       day 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/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  success-
               fully.

       -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

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)