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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 user-
               name.

       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 exe-
       cuted.  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 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.

       -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 submit-
       ted 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.

       -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]MMD-
              Dhhmm).

ENVIRONMENT
       SHELL   The  value  of  the SHELL environment variable at the time of at invocation will determine which
               shell is used to execute the at job commands. 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  vari-
       ables 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  unde-
       fined 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.



local                              Nov 1996                              AT(1)