at



AT(1)                      OpenBSD Reference Manual                      AT(1)


NAME

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


SYNOPSIS

     at [-bm] [-f file] [-l [user ...]] [-q queue] -t time_arg | timespec
     at -c | -r job ...
     batch [-m] [-f file] [-q queue] [timespec]


DESCRIPTION

     at and batch read commands from standard input or a specified file which
     are to be executed at a later time, via the user's shell as specified by
     the SHELL environment variable.  If SHELL is not set, the shell in the
     user's password database entry is used instead.  If all else fails, sh(1)
     will be used.

     The related programs are as follows:

     at      Executes commands at a specified time.

     batch   Executes commands when system load levels permit.  In other
             words, when the load average drops below 1.5, or the value
             specified in the invocation of cron(8).

     The options are as follows:

     -b      An alias for batch.

     -c job ...
             Prints the jobs listed on the command line to standard output.

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

     -l [user ...]
             Displays the queue of jobs which are currently awaiting
             execution.  If a user argument is specified, only jobs belonging
             to that user will be displayed.  Unless the user is the
             superuser, only the user's own jobs will be displayed.

     -m      Send mail to the user when the job has completed, even if there
             was no output.

     -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 c queue is the default for at and the E queue for
             batch.  Queues with higher letters run with increased niceness.
             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 the user specified the -l option and at is given a
             specific queue, only jobs pending in that queue will be shown.

     -r job ...
             Remove the specified job(s) from the at queue.

     -t time_arg
             Specify the job time.  The argument should be of the form
             [[cc]yy]mmddHHMM[.SS], where the parts of the argument represent
             the following:

                   ccyy    Year.  If yy is specified, but cc is not, a value
                           for yy between 69 and 99 results in a cc value of
                           19.  Otherwise, a cc value of 20 is used.
                   mm      Month: a number from 1 to 12.
                   dd      Day: a number from 1 to 31.
                   HH      Hour: a number from 0 to 23.
                   MM      Minute: a number from 0 to 59.
                   SS      Second: a number from 0 to 60 (permitting a leap
                           second), preceded by a period.  The default is 0.

     at allows some moderately complex timespec specifications.  It accepts
     times of the form HHMM or 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
     dd.mm.ccyy, dd.mm.yy, mm/dd/ccyy, mm/dd/yy, mmddccyy, or mmddyy.

     The year may be given as two or four digits.  If the year is given as two
     digits, it is taken to occur as soon as possible in the future, which may
     be in the next century -- unless it's last year, in which case it's
     considered to be a typo.

     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.  To run a job at 1am tomorrow, you would do at 1am tomorrow.

     The at utility also supports the time format used by touch(1) (see the -t
     option).

     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, TERMCAP, 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 user ID.  The
     user will be mailed standard error and standard output from his commands,
     if any.  Mail will be sent using sendmail(8).  If at is executed from a
     su(1) shell, the owner of the login shell will receive the mail.

     For non-root users, permission to run at is determined by the files
     /var/cron/at.allow and /var/cron/at.deny.  Note: these files must be
     readable by group crontab (if they exist).

     If the file /var/cron/at.allow exists, only usernames mentioned in it are
     allowed to use at.  If /var/cron/at.allow does not exist,
     /var/cron/at.deny is checked.  Every username not mentioned in it is then
     allowed to use at.  If neither exists, only the superuser is allowed to
     run at.

     An empty /var/cron/at.deny means that every user is allowed to use these
     commands.  This is the default configuration.


FILES

     /var/cron/atjobs    directory containing job files
     /var/cron/at.allow  allow permission control
     /var/cron/at.deny   deny permission control


EXIT STATUS

     The at utility exits with one of the following values:

           0       Jobs were successfully submitted, removed, or listed.
           >0      An error occurred.


SEE ALSO

     atq(1), atrm(1), nice(1), sh(1), touch(1), umask(2), cron(8), sendmail(8)


STANDARDS

     The at and batch utilities are compliant with the IEEE Std 1003.1-2008
     (``POSIX.1'') specification.

     The at flags [-bc] and the batch flags [-fmq] are extensions to that
     specification.

     Behaviour for the -l flag differs between this implementation and IEEE
     Std 1003.1-2008 (``POSIX.1'').


AUTHORS

     at was mostly written by Thomas Koenig <ig25@rz.uni-karlsruhe.de>.  The
     time parsing routines are by David Parsons <orc@pell.chi.il.us>.


BUGS

     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.

OpenBSD 5.4                      July 16, 2013                     OpenBSD 5.4

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