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at(1)

Name | Synopsis | Description | Options | Operands | Usage | Examples | Environment Variables | Exit Status | Files | Attributes | See Also | Notes

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(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. Execution 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 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 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 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

---

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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 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(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 Also

auths(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.

Name | Synopsis | Description | Options | Operands | Usage | Examples | Environment Variables | Exit Status | Files | Attributes | See Also | Notes