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AT(1)                      Linux Programmer's Manual                     AT(1)



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

SYNOPSIS
       at [-V] [-q queue] [-f file] [-mMlbv] TIME
       at [-V] [-q queue] [-f file] [-mMlbv] -t time_arg
       at -c job [job...]
       at [ -rd ] job [job...]
       atq [-V] [-q queue]
       atrm [-V] job [job...]
       batch

DESCRIPTION
       at  and batch read commands from standard input or a specified file which are to be
       executed at a later time.

       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 MMDDYY or MM/DD/YY or DD.MM.YY or YYYY-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-3.1.10/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 TERM, DISPLAY and _) and the umask are retained from the time of
       invocation.  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  men-
       tioned 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.

       -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 out-
               put.

       -M      Never send mail to the user.

       -f file Reads the job from file rather than standard input.

       -l      Is an alias for atq.

       -r      Is an alias for atrm.

       -d      Is an alias for atrm.


       -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.

       -t time_arg
              Submit the job to be run at the time specified by the time_arg option
              argument,  which  must  have  the  same  format  as specified for the
              touch(1) utility's -t time option argument ([[CC]YY]MMDDhhmm).

ENVIRONMENT
       SHELL   The value of the SHELL environment variable at the time of at  invo-
               cation will determine which shell is used to execute the at job com-
               mands. If SHELL is unset when at is invoked, the user's login  shell
               will be used; otherwise, if SHELL is set when at is invoked, it must
               contain the path of a shell interpreter executable that will be used
               to run the commands at the specified time.

       at  will  record  the  values of environment variables present at time of at
       invocation. When the commands are  run  at  the   specified  time,  at  will
       restore  these  variables  to  their  recorded values .  These variables are
       excluded from this processing and are never set by at when the commands  are
       run :
       TERM, DISPLAY, SHELLOPTS, _, PPID, BASH_VERSINFO, EUID, UID, GROUPS.
       If  the  user  submitting  the  at job is not the super-user, variables that
       alter the behaviour of the loader ld.so(8), such as LD_LIBRARY_PATH , cannot
       be recorded and restored by at .


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 com-
       peting 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 AT rz.de.



local                              Nov 1996                              AT(1)

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