269 lines
5.6 KiB
Groff
269 lines
5.6 KiB
Groff
.\" $Id: at.man,v 1.3 1995/08/21 12:32:47 ache Exp $
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.Dd April 12, 1995
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.Dt "AT" 1
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.Os "FreeBSD 2.1"
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.Sh NAME
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.Nm at, batch, atq, atrm
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.Nd queue, examine or delete jobs for later execution
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.Sh SYNOPSIS
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.Nm at
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.Op Fl V
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.Op Fl q Ar queue
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.Op Fl f Ar file
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.Op Fl mldbv
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.Ar time
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.Pp
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.Nm at
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.Op Fl V
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.Fl c Ar job Op Ar job ...
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.Pp
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.Nm atq
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.Op Fl V
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.Op Fl q Ar queue
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.Op Fl v
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.Pp
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.Nm atrm
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.Op Fl V
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.Ar job
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.Op Ar job ...
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.Pp
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.Nm batch
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.Op Fl V
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.Op Fl q Ar queue
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.Op Fl f Ar file
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.Op Fl mv
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.Op Ar time
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.Sh DESCRIPTION
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.Nm At
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and
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.Nm batch
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read commands from standard input or a specified file which are to
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be executed at a later time, using
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.Xr sh 1 .
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.Bl -tag -width indent
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.It Nm at
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executes commands at a specified time;
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.It Nm atq
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lists the user's pending jobs, unless the user is the superuser; in that
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case, everybody's jobs are listed;
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.It Nm atrm
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deletes jobs;
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.It Nm batch
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executes commands when system load levels permit; in other words, when the load average
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drops below _LOADAVG_MX, or the value specified in the invocation of
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.Nm atrun .
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.El
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.Pp
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.Nm At
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allows some moderately complex
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.Ar time
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specifications. It accepts times of the form
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.Ar HHMM
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or
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.Ar HH:MM
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to run a job at a specific time of day.
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(If that time is already past, the next day is assumed.)
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You may also specify
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.Nm midnight ,
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.Nm noon ,
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or
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.Nm teatime
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(4pm)
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and you can have a time-of-day suffixed with
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.Nm AM
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or
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.Nm PM
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for running in the morning or the evening.
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You can also say what day the job will be run,
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by giving a date in the form
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.Ar \%month-name day
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with an optional
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.Ar year ,
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or giving a date of the form
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.Ar MMDDYY
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or
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.Ar MM/DD/YY
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or
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.Ar DD.MM.YY .
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The specification of a date must follow the specification of
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the time of day.
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You can also give times like
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.Op Nm now
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.Nm + Ar count \%time-units ,
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where the time-units can be
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.Nm minutes ,
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.Nm hours ,
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.Nm days ,
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or
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.Nm weeks
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and you can tell
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.Nm at
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to run the job today by suffixing the time with
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.Nm today
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and to run the job tomorrow by suffixing the time with
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.Nm tomorrow.
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.Pp
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For example, to run a job at 4pm three days from now, you would do
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.Nm at 4pm + 3 days ,
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to run a job at 10:00am on July 31, you would do
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.Nm at 10am Jul 31
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and to run a job at 1am tomorrow, you would do
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.Nm at 1am tomorrow.
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.Pp
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For both
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.Nm at
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and
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.Nm batch ,
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commands are read from standard input or the file specified
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with the
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.Fl f
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option and executed.
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The working directory, the environment (except for the variables
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.Nm TERM ,
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.Nm TERMCAP ,
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.Nm DISPLAY
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and
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.Nm _ )
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and the
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.Ar umask
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are retained from the time of invocation.
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An
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.Nm at
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or
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.Nm batch
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command invoked from a
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.Xr su 1
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shell will retain the current userid.
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The user will be mailed standard error and standard output from his
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commands, if any. Mail will be sent using the command
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.Xr sendmail 8 .
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If
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.Nm at
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is executed from a
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.Xr su 1
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shell, the owner of the login shell will receive the mail.
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.Pp
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The superuser may use these commands in any case.
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For other users, permission to use at is determined by the files
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.Pa _PERM_PATH/at.allow
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and
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.Pa _PERM_PATH/at.deny .
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.Pp
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If the file
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.Pa _PERM_PATH/at.allow
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exists, only usernames mentioned in it are allowed to use
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.Nm at .
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.Pp
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If
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.Pa _PERM_PATH/at.allow
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does not exist,
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.Pa _PERM_PATH/at.deny
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is checked, every username not mentioned in it is then allowed
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to use
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.Nm at .
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.Pp
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If neither exists, only the superuser is allowed use of
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.Nm at .
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This is the default configuration.
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.Pp
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An empty
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.Pa _PERM_PATH/at.deny
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means that every user is allowed use these commands.
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.Sh OPTIONS
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.Bl -tag -width indent
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.It Fl V
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prints the version number to standard error.
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.It Fl q Ar queue
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uses the specified queue.
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A queue designation consists of a single letter; valid queue designations
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range from
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.Nm a
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to
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.Nm z .
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and
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.Nm A
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to
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.Nm Z .
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The
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.Nm _DEFAULT_AT_QUEUE
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queue is the default for
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.Nm at
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and the
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.Nm _DEFAULT_BATCH_QUEUE
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queue for
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.Nm batch .
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Queues with higher letters run with increased niceness.
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If a job is submitted to a queue designated with an uppercase letter, it
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is treated as if it had been submitted to batch at that time.
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If
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.Nm atq
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is given a specific queue, it will only show jobs pending in that queue.
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.It Fl m
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Send mail to the user when the job has completed even if there was no
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output.
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.It Fl f Ar file
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Reads the job from
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.Ar file
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rather than standard input.
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.It Fl l
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Is an alias for
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.Nm atq.
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.It Fl d
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Is an alias for
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.Nm atrm.
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.It Fl b
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Is an alias for
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.Nm batch.
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.It Fl v
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For
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.Nm atq ,
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shows completed but not yet deleted jobs in the queue; otherwise
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shows the time the job will be executed.
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.It Fl c
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Cats the jobs listed on the command line to standart output.
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.Sh FILES
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.Bl -tag -width _ATJOB_DIR/_LOCKFILE -compact
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.It Pa _ATJOB_DIR
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Directory containing job files
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.It Pa _ATSPOOL_DIR
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Directory containing output spool files
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.It Pa /var/run/utmp
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Login records
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.It Pa _PERM_PATH/at.allow
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Allow permission control
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.It Pa _PERM_PATH/at.deny
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Deny permission control
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.It Pa _ATJOB_DIR/_LOCKFILE
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Job-creation lock file.
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.Sh SEE ALSO
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.Xr cron 8 ,
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.Xr nice 1 ,
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.Xr umask 2 ,
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.Xr sh 1 ,
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.Xr sendmail 8 ,
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.Xr atrun 8 .
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.El
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.Sh BUGS
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.Pp
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If the file
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.Pa /var/run/utmp
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is not available or corrupted, or if the user is not logged on at the
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time
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.Nm at
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is invoked, the mail is sent to the userid found
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in the environment variable
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.Nm LOGNAME .
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If that is undefined or empty, the current userid is assumed.
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.Pp
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.Nm At
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and
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.Nm batch
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as presently implemented are not suitable when users are competing for
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resources.
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If this is the case for your site, you might want to consider another
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batch system, such as
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.Nm nqs .
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.Sh AUTHOR
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At was mostly written by Thomas Koenig, ig25@rz.uni-karlsruhe.de.
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The time parsing routines are by David Parsons, orc@pell.chi.il.us.
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