AT(1) User Commands AT(1)
NAME
at, batch - execute commands at a later time
SYNOPSIS
/usr/bin/at [
-c |
-k |
-s] [
-m] [
-f file] [
-p project]
[
-q queuename]
-t time /usr/bin/at [
-c |
-k |
-s] [
-m] [
-f file] [
-p project]
[
-q queuename]
timespec...
/usr/bin/at -l [
-p project] [
-q queuename] [
at_job_id ...]
/usr/bin/at -r at_job_id ... /usr/bin/batch [
-p project]
/usr/xpg4/bin/at [
-c |
-k |
-s] [
-m] [
-f file] [
-p project]
[
-q queuename]
-t time /usr/xpg4/bin/at [
-c |
-k |
-s] [
-m] [
-f file] [
-p project]
[
-q queuename]
timespec...
/usr/xpg4/bin/at -l [
-p project] [
-q queuename]
[
at_job_id ...]
/usr/xpg4/bin/at -r at_job_id ... /usr/xpg4/bin/batch [
-p project]
DESCRIPTION
at The
at utility reads commands from standard input and groups them
together as an
at-job, to be executed at a later time.
The at-job is executed in a separate invocation of the shell, running in
a separate process group with no controlling terminal, except that the
environment variables, current working directory, file creation mask (see
umask(1)), and system resource limits (for
sh and
ksh only, see
ulimit(1)) in effect when the
at utility is executed is retained and used
when the at-job is executed.
When the at-job is submitted, the
at_job_id and scheduled time are
written to standard error. The
at_job_id is an identifier that is a
string consisting solely of alphanumeric characters and the period
character. The
at_job_id is assigned by the system when the job is
scheduled such that it uniquely identifies a particular job.
User notification and the processing of the job's standard output and
standard error are described under the
-m option.
Users are permitted to use
at and
batch (see below) 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 a user with the
solaris.jobs.user authorization is allowed to submit a job. If only
at.deny exists and is empty, global usage is permitted. The
at.allow and
at.deny files consist of one user name per line.
cron and
at jobs are not be executed if the user's account is locked.
Only accounts which are not locked as defined in
shadow(5) will have
their job or process executed.
batch The
batch utility reads commands to be executed at a later time.
Commands of the forms:
/usr/bin/batch [-p project]
/usr/xpg4/bin/batch [-p project]
are respectively equivalent to:
/usr/bin/at -q b [-p project] now
/usr/xpg4/bin/at -q b -m [-p project] now
where queue
b is a special
at queue, specifically for batch jobs. Batch
jobs are submitted to the batch queue for immediate execution. Execution
of submitted jobs can be delayed by limits on the number of jobs allowed
to run concurrently. See
queuedefs(5).
OPTIONS
If the
-c,
-k, or
-s options are not specified, the
SHELL environment
variable by default determines which shell to use.
If
SHELL is unset or
NULL,
/usr/bin/sh is used.
The following options are supported:
-c C shell.
csh(1) is used to execute the at-job.
-k Korn shell.
ksh(1) is used to execute the at-job.
-s Bourne shell.
sh(1) is used to execute the at-job.
-f file Specifies the path of a file to be used as the source of
the at-job, instead of standard input.
-l (The letter ell.) Reports all jobs scheduled for the
invoking user if no
at_job_id operands are specified. If
at_job_ids are specified, reports only information for
these jobs.
-m Sends mail to the invoking user after the at-job has
run, announcing its completion. Standard output and
standard error produced by the at-job are mailed to the
user as well, unless redirected elsewhere. Mail is sent
even if the job produces no output.
If
-m is not used, the job's standard output and
standard error is provided to the user by means of mail,
unless they are redirected elsewhere; if there is no
such output to provide, the user is not notified of the
job's completion.
-p project Specifies under which project the
at or
batch job is
run. When used with the
-l option, limits the search to
that particular project. Values for
project is
interpreted first as a project name, and then as a
possible project
ID, if entirely numeric. By default,
the user's current project is used.
-q queuename Specifies in which queue to schedule a job for
submission. When used with the
-l option, limits the
search to that particular queue. Values for
queuename are limited to the lower case letters
a through
z. By
default, at-jobs are scheduled in queue
a. In contrast,
queue
b is reserved for batch jobs. Since queue
c is
reserved for cron jobs, it can not be used with the
-q option.
-r at_job_id Removes the jobs with the specified
at_job_id operands
that were previously scheduled by the
at utility.
-t time Submits the job to be run at the time specified by the
time option-argument, which must have the format as
specified by the
touch(1) utility.
OPERANDS
The following operands are supported:
at_job_id The name reported by a previous invocation of the
at utility at the time the job was scheduled.
timespec Submit the job to be run at the date and time specified.
All of the
timespec operands are interpreted as if they
were separated by space characters and concatenated. The
date and time are interpreted as being in the timezone of
the user (as determined by the
TZ variable), unless a
timezone name appears as part of
time below.
In the "C" locale, the following describes the three parts
of the time specification string. All of the values from
the
LC_TIME categories in the "C" locale are recognized in
a case-insensitive manner.
time The
time can be specified as one, two or four
digits. One- and two-digit numbers are taken
to be hours, four-digit numbers to be hours
and minutes. The time can alternatively be
specified as two numbers separated by a
colon, meaning
hour:minute. An AM/PM
indication (one of the values from the
am_pm keywords in the
LC_TIME locale category) can
follow the time; otherwise, a 24-hour clock
time is understood. A timezone name of
GMT,
UCT, or
ZULU (case insensitive) can follow to
specify that the time is in Coordinated
Universal Time. Other timezones can be
specified using the
TZ environment variable.
The
time field can also be one of the
following tokens in the "C" locale:
midnight Indicates the time 12:00 am
(00:00).
noon Indicates the time 12:00 pm.
now Indicate the current day and
time. Invoking
at now submits an
at-job for potentially immediate
execution (that is, subject only
to unspecified scheduling
delays).
date An optional
date can be specified as either a
month name (one of the values from the
mon or
abmon keywords in the
LC_TIME locale
category) followed by a day number (and
possibly year number preceded by a comma) or
a day of the week (one of the values from the
day or
abday keywords in the
LC_TIME locale
category). Two special days are recognized in
the "C" locale:
today Indicates the current day.
tomorrow Indicates the day following the
current day.
If no
date is given,
today is assumed if the
given time is greater than the current time,
and
tomorrow is assumed if it is less. If the
given month is less than the current month
(and no year is given), next year is assumed.
increment The optional
increment is a number preceded
by a plus sign (
+) and suffixed by one of the
following:
minutes,
hours,
days,
weeks,
months, or
years. (The singular forms are
also accepted.) The keyword
next is
equivalent to an increment number of
+ 1. For
example, the following are equivalent
commands:
at 2pm + 1 week at 2pm next weekUSAGE
The format of the
at command line shown here is guaranteed only for the
"C" locale. Other locales are not supported for
midnight,
noon,
now,
mon,
abmon,
day,
abday,
today,
tomorrow,
minutes,
hours,
days,
weeks,
months,
years, and
next.
Since the commands run in a separate shell invocation, running in a
separate process group with no controlling terminal, open file
descriptors, traps and priority inherited from the invoking environment
are lost.
EXAMPLES
at Example 1: Typical Sequence at a Terminal
This sequence can be used at a terminal:
$ at -m 0730 tomorrow
sort < file >outfile
<EOT>
Example 2: Redirecting Output
This sequence, which demonstrates redirecting standard error to a pipe,
is useful in a command procedure (the sequence of output redirection
specifications is significant):
$ at now + 1 hour <<!
diff file1 file2 2>&1 >outfile | mailx mygroup
Example 3: Self-rescheduling a Job
To have a job reschedule itself,
at can be invoked from within the at-
job. For example, this "daily-processing" script named
my.daily runs
every day (although
crontab is a more appropriate vehicle for such work):
# my.daily runs every day
at now tomorrow < my.daily
daily-processing
Example 4: Various Time and Operand Presentations
The spacing of the three portions of the "C" locale
timespec is quite
flexible as long as there are no ambiguities. Examples of various times
and operand presentations include:
at 0815am Jan 24
at 8 :15amjan24
at now "+ 1day"
at 5 pm FRIday
at '17
utc+
30minutes'
batch Example 5: Typical Sequence at a Terminal
This sequence can be used at a terminal:
$ batch
sort <file >outfile
<EOT>
Example 6: Redirecting Output
This sequence, which demonstrates redirecting standard error to a pipe,
is useful in a command procedure (the sequence of output redirection
specifications is significant):
$ batch <<!
diff file1 file2 2>&1 >outfile | mailx mygroup
!
ENVIRONMENT VARIABLES
See
environ(7) for descriptions of the following environment variables
that affect the execution of
at and
batch:
LANG,
LC_ALL,
LC_CTYPE,
LC_MESSAGES,
NLSPATH, and
LC_TIME.
DATEMSK If the environment variable
DATEMSK is set,
at uses its value
as the full path name of a template file containing format
strings. The strings consist of format specifiers and text
characters that are used to provide a richer set of allowable
date formats in different languages by appropriate settings
of the environment variable
LANG or
LC_TIME. The list of
allowable format specifiers is located in the
getdate(3C) manual page. The formats described in the
OPERANDS section
for the
time and
date arguments, the special names
noon,
midnight,
now,
next,
today,
tomorrow, and the
increment argument are not recognized when
DATEMSK is set.
SHELL Determine a name of a command interpreter to be used to
invoke the at-job. If the variable is unset or
NULL,
sh is
used. If it is set to a value other than
sh, the
implementation uses that shell; a warning diagnostic is
printed telling which shell will be used.
TZ Determine the timezone. The job is submitted for execution at
the time specified by
timespec or
-t time relative to the
timezone specified by the
TZ variable. If
timespec specifies
a timezone, it overrides
TZ. If
timespec does not specify a
timezone and
TZ is unset or
NULL, an unspecified default
timezone is used.
EXIT STATUS
The following exit values are returned:
0 The
at utility successfully submitted, removed or listed a job or
jobs.
>0 An error occurred, and the job will not be scheduled.
FILES
/usr/lib/cron/at.allow names of users, one per line, who are
authorized access to the
at and
batch utilities
/usr/lib/cron/at.deny names of users, one per line, who are denied
access to the
at and
batch utilities
ATTRIBUTES
See
attributes(7) for descriptions of the following attributes:
/usr/bin/at +--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|CSI | Not enabled |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
/usr/xpg4/bin/at +--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|CSI | Not enabled |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
/usr/bin/batch +--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|CSI | Enabled |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
/usr/xpg4/bin/batch +--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|CSI | Enabled |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
SEE ALSO
auths(1),
crontab(1),
csh(1),
date(1),
ksh(1),
sh(1),
touch(1),
ulimit(1),
umask(1),
getdate(3C),
auth_attr(5),
queuedefs(5),
shadow(5),
attributes(7),
environ(7),
standards(7),
cron(8)NOTES
Regardless of queue used,
cron(8) has a limit of 100 jobs in execution at
any time.
There can be delays in
cron at job execution. In some cases, these delays
can compound to the point that
cron job processing appears to be hung.
All jobs are executed eventually. When the delays are excessive, the only
workaround is to kill and restart
cron.
April 13, 2005
AT(1)