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


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


       at [-V] [-q queue] [-f file] [-mldbv] TIME
       at [-V] [-q queue] [-f file] [-mldbv] -t time_arg
       at -c job [job...]
       atq [-V] [-q queue]
       atrm [-V] job [job...]
       batch [-V] [-q queue] [-f file] [-mv] [TIME]


       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 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, job class.

       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 atrun.

       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
       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.  The specifi-
       cation 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

       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 com-
       mands, 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

       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 user-
       name 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  com-
       mands, this is the default configuration.


       -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

       If a job is submitted to a queue designated with an  uppercase  letter,
       it  is  treated  as if it had been submitted to batch at that time.  If
       atq is given a specific queue, it will only show jobs pending  in  that

       -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.

       -l      Is an alias for atq.

       -d      Is an alias for atrm.

       -v      Shows the time the job will be executed.

       Times displayed will be in the format "1997-02-20 14:50"  unless
       the  environment  variable POSIXLY_CORRECT is set; then, it will
       be "Thu Feb 20 14:50:00 1997".

       -c     cats the jobs listed on the command line to standard out-

       -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).


       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; other-
               wise, if SHELL is set when at is invoked, it  must  con-
               tain  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   speci-
       fied  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 :
       If the user submitting the at job is not the  super-user,  vari-
       ables  that  alter the behaviour of the loader, such as
       LD_LIBRARY_PATH , cannot be recorded and restored by at .




       cron(1), nice(1), sh(1), umask(2), atd(8).


       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


       At  was  mostly  written  by  Thomas  Koenig,  ig25@rz.uni-karl-

local                              Nov 1996                              AT(1)

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