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 queue‐
name] -t time
/usr/xpg4/bin/at [-c | -k | -s] [-m] [-f file] [-p project] [-q queue‐
name] 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(4) 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. Execu‐
tion of submitted jobs can be delayed by limits on the number of jobs
allowed to run concurrently. See queuedefs(4).
OPTIONS
If the -c, -k, or -s options are not specified, the SHELL environment
variable by default determines which shell to use.
For /usr/xpg4/bin/at and /usr/xpg4/bin/batch, if SHELL is unset or
NULL, /usr/xpg4/bin/sh is used.
For usr/bin/at and /usr/bin/batch, if SHELL is unset or NULL, /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 stan‐
dard 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 inter‐
preted 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 submis‐
sion. When used with the -l option, limits the search
to that particular queue. Values for queuename are lim‐
ited 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 speci‐
fied. All of the timespec operands are interpreted as
if they were separated by space characters and concate‐
nated. The date and time are interpreted as being in
the timezone of the user (as determined by the TZ vari‐
able), 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 val‐
ues 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 num‐
bers 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, mean‐
ing hour:minute. An AM/PM indication
(one of the values from the am_pm key‐
words 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 spec‐
ify 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 recog‐
nized 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 pre‐
ceded 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 week
USAGE
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 descrip‐
tors, 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(5) 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 contain‐
ing format strings. The strings consist of format spec‐
ifiers and text characters that are used to provide a
richer set of allowable date formats in different lan‐
guages by appropriate settings of the environment vari‐
able 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, mid‐
night, 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 execu‐
tion at the time specified by timespec or -t time rela‐
tive 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 util‐
ities
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
/usr/bin/at
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWcsu │
├─────────────────────────────┼─────────────────────────────┤
│CSI │Not enabled │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
└─────────────────────────────┴─────────────────────────────┘
/usr/xpg4/bin/at
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWxcu4 │
├─────────────────────────────┼─────────────────────────────┤
│CSI │Not enabled │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
└─────────────────────────────┴─────────────────────────────┘
/usr/bin/batch
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWesu │
├─────────────────────────────┼─────────────────────────────┤
│CSI │Enabled │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
└─────────────────────────────┴─────────────────────────────┘
/usr/xpg4/bin/batch
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWxcu4 │
├─────────────────────────────┼─────────────────────────────┤
│CSI │Enabled │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOauths(1), crontab(1), csh(1), date(1), ksh(1), sh(1), touch(1),
ulimit(1), umask(1), cron(1M), getdate(3C), auth_attr(4), shadow(4),
queuedefs(4), attributes(5), environ(5), standards(5)NOTES
Regardless of queue used, cron(1M) 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.
SunOS 5.10 13 Apr 2005 at(1)
