AT(1-SysV)          RISC/os Reference Manual           AT(1-SysV)



NAME
     at, batch - execute commands at a later time

SYNOPSIS
     at time [ date ] [ + increment ]
     at -r job ...
     at -l [ job ... ]

     batch

DESCRIPTION
     at and batch read commands from standard input to be exe-
     cuted at a later time.  at allows you to specify when the
     commands should be executed, while jobs queued with batch
     will execute when system load level permits.  at may be used
     with the following options:

     -r   Removes jobs previously scheduled with at.

     -l   Reports all jobs scheduled for the invoking user.

     Standard output and standard error output are mailed to the
     user unless they are redirected elsewhere.  The shell
     environment variables, current directory, umask, and ulimit
     are retained when the commands are executed.  Open file
     descriptors, traps, and priority are lost.

     Users are permitted to use at if their name appears in the
     file /usr/lib/cron/at.allow. If that file does not exist,
     the file /usr/lib/cron/at.deny is checked to determine if
     the user should be denied access to at.  If neither file
     exists, only root is allowed to submit a job.  If at.deny is
     empty, global usage is permitted.  The allow/deny files con-
     sist of one user name per line.  These files can only be
     modified by the superuser.

     The time may be specified as 1, 2, or 4 digits.  One and two
     digit numbers are taken to be hours, four digits to be hours
     and minutes.  The time may alternately be specified as two
     numbers separated by a colon, meaning hour:minute.  A suffix
     am or pm may be appended; otherwise a 24-hour clock time is
     understood.  The suffix zulu may be used to indicate GMT.
     The special names noon, midnight, now, and next are also
     recognized.

     An optional date may be specified as either a month name
     followed by a day number (and possibly year number preceded
     by an optional comma) or a day of the week (fully spelled or
     abbreviated to three characters).  Two special ``days'',
     today and tomorrow are recognized.  If no date is given,
     today is assumed if the given hour is greater than the
     current hour and tomorrow is assumed if it is less.  If the



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     given month is less than the current month (and no year is
     given), next year is assumed.

     The optional increment is simply a number suffixed by one of
     the following:  minutes, hours, days, weeks, months, or
     years.  (The singular form is also accepted.)

     Thus legitimate commands include:

               at 0815am Jan 24
               at 8:15am Jan 24
               at now + 1 day
               at 5 pm Friday

     at and batch write the job number and schedule time to stan-
     dard error.

     batch submits a batch job.  It is almost equivalent to
     ``at now'', but not quite.  For one, it goes into a dif-
     ferent queue.  For another, ``at now'' will respond with the
     error message too late.

     at -r removes jobs previously scheduled by at or batch.  The
     job number is the number given to you previously by the at
     or batch command.  You can also get job numbers by typing at
     -l.  You can only remove your own jobs unless you are the
     super-user.

EXAMPLES
     The at and batch commands read from standard input the com-
     mands to be executed at a later time.  sh(1) provides dif-
     ferent ways of specifying standard input.  Within your com-
     mands, it may be useful to redirect standard output.

     This sequence can be used at a terminal:
               batch
               sort filename >outfile
               <control-D> (hold down 'control' and depress 'D')

     This sequence, which demonstrates redirecting standard error
     to a pipe, is useful in a shell procedure (the sequence of
     output redirection specifications is significant):
               batch <<!
               sort filename 2>&1 >outfile | mail loginid
               !

     To have a job reschedule itself, invoke at from within the
     shell procedure, by including code similar to the following
     within the shell file:

               echo "sh shellfile" | at 1900 thursday next week




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FILES
     /usr/lib/cron            main cron directory
     /usr/lib/cron/at.allow   list of allowed users
     /usr/lib/cron/at.deny    list of denied users
     /usr/lib/cron/queue      scheduling information
     /usr/spool/cron/atjobs   spool area

SEE ALSO
     kill(1), mail(1), nice(1), ps(1), sh(1), sort(1).
     cron(1M) in the System Administrator's Reference Manual.

DIAGNOSTICS
     Complains about various syntax errors and times out of
     range.









































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