MAN sezione 1 - Torna all'indice
MAN PAGE: AT(1)Contents
at, batch, atq, atrm - queue, examine or delete jobs for
later execution
at [-V] [-q queue] [-f file] [-mldbv] TIME
at -c job [job...]
atq [-V] [-q queue]
atrm [-V] job [job...]
batch [-V] [-q queue] [-f file] [-mv] [TIME]
at and batch read commands from standard input or a speci
fied file which are to be executed at a later time, using
/bin/sh.
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. The format of the output lines (one for
each job) is: Job number, date, hour, job class.
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
atrun.
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 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 + 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/doc/at/timespec.
For both at and batch, commands are read from standard
input or the file specified with the -f option and exe
cuted. 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 stan
dard output from his commands, 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 username 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 commands, this is the default configuration.
-V prints the version number to standard error.
-q queue
uses the specified queue. A queue designation
consists of a single letter; valid queue designa
tions 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 upper
case 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.
-m Send mail to the user when the job has completed
even if there was no output.
-f file Reads the job from file rather than standard
input.
-l Is an alias for atq.
-d Is an alias for atrm.
-v Shows the time the job will be executed.
Times displayed will be in the format "1997-02-20 14:50"
unless the environment variable POSIXLY_CORRECT is set;
then, it will be "Thu Feb 20 14:50:00 1996".
-c cats the jobs listed on the command line to stan
dard output.
/var/spool/atjobs
/var/spool/atspool
/proc/loadavg
/var/run/utmp
/etc/at.allow
/etc/at.deny
cron(1), nice(1), sh(1), umask(2), atd(8).
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 cur
rent 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.
At was mostly written by Thomas Koenig, ig25@rz.uni-karl
sruhe.de.
local Nov 1996 3 |
