AT(1)                                                                                                                      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 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 mid-
       night, 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-3.1.12/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 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 aver-
               age 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/at
       /var/spool/at/spool
       /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, ig25ATrz.de.



                                                           2009-11-14                                                      AT(1)