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



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

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 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 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 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 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  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
       /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	 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.

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 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 out-
	      put.

       -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  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 :
       TERM, DISPLAY, SHELLOPTS, _,  PPID,  BASH_VERSINFO,  EUID,  UID,
       GROUPS.
       If  the	user submitting the at job is not the super-user, vari-
       ables 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 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,  ig25@rz.uni-karls-
       ruhe.de.



local				   Nov 1996				 AT(1)