NAME
at,
batch,
atq,
atrm —
queue, examine or delete jobs
for later execution
SYNOPSIS
at |
[-bdlmrVv]
[-f file]
[-q queue]
-t [[CC]YY]MMDDhhmm[.SS] |
at |
[-bdlmrVv]
[-f file]
[-q queue]
time |
batch |
[-mVv]
[-f file]
[-q queue]
[-t
[[CC]YY]MMDDhhmm[.SS]] |
batch |
[-mVv]
[-f file]
[-q queue]
[time] |
DESCRIPTION
at and
batch read commands from standard
input or a specified file which are to be executed at a later time, using
sh(1).
-
-
- at
- Executes commands at a specified time.
-
-
- atq
- Lists the user's pending jobs, unless the user is the
superuser. In that case, everybody's jobs are listed.
-
-
- atrm
- Deletes jobs.
-
-
- 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
atrun(8).
at allows some moderately complex
time
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
MMDDYY or
MM/DD/YY or
DD.MM.YY. The specification of a date must follow the
specification of the time of day. You can also give times like
[
now] or
[
now] ‘+
count
%time-units’, where the time-units can be ‘minutes’,
‘hours’, ‘days’, ‘weeks’,
‘months’, or ‘years’ 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.
Alternatively the time may be specified in a language-neutral fashion by using
the
-t options.
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
userid. The user will be mailed standard error and standard output from his
commands, if any. Mail will be sent using the command
sendmail(1). 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
/var/at/at.allow and
/var/at/at.deny.
If the file
/var/at/at.allow exists, only usernames mentioned
in it are allowed to use
at.
If
/var/at/at.allow does not exist,
/var/at/at.deny is checked; every username not mentioned in
it is then allowed to use
at.
If neither exists, only the superuser is allowed use of
at.
An empty
/var/at/at.deny means that every user is allowed use
these commands. This is the default configuration.
OPTIONS
-
-
- -b
- Is an alias for batch.
-
-
- -c
- Cats the jobs listed on the command line to standard
output.
-
-
- -d
- Is an alias for atrm.
-
-
- -f
file
- Reads the job from file rather than
standard input.
-
-
- -l
- Is an alias for atq.
-
-
- -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 atq is given a
specific queue, it will only show jobs pending in that queue.
-
-
- -r
- Is an alias for atrm.
-
-
- -t
- For both at and batch,
the time may be specified in a language-neutral format consisting of:
- CC
- The first two digits of the year (the century).
- YY
- The second two digits of the 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
- The month of the year, from 01 to 12.
- DD
- The day of the month, from 01 to 31.
- hh
- The hour of the day, from 00 to 23.
- mm
- The minute of the hour, from 00 to 59.
- SS
- The second of the minute, from 00 to 61.
-
-
- -V
- Prints the version number to standard error.
-
-
- -v
- For atq, shows completed but not yet
deleted jobs in the queue. Otherwise shows the time the job will be
executed.
FILES
- /var/at/jobs
- Directory containing job files
- /var/at/spool
- Directory containing output spool files
- /var/run/utmp
- Login records
- /var/at/at.allow
- Allow permission control
- /var/at/at.deny
- Deny permission control
- /var/at/.lockfile
- Job-creation lock file.
SEE ALSO
nice(1),
sendmail(1),
sh(1),
umask(2),
atrun(8),
cron(8)
STANDARDS
The
at and
batch utilities conform to
IEEE Std 1003.2-1992 (“POSIX.2”).
AUTHORS
at was mostly written by
Thomas Koenig
<
ig25@rz.uni-karlsruhe.de>.
The time parsing routines are implemented by
David
Parsons
<
orc@pell.chi.il.us>.
BUGS
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.