at(1)
NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | USAGE | EXAMPLES | ENVIRONMENT VARIABLES | EXIT STATUS | FILES | ATTRIBUTES | SUMMARY OF TRUSTED SOLARIS CHANGES | SEE ALSO | NOTES
NAME
- at, batch– execute commands at a later time
SYNOPSIS
-
at [-c| -k| -s] [-m] [-f file] [-p project] [-q queuename] -t time
at [-c| -k| -s] [-P] [-m] [-f file] [-p project] [-q queuename] timespec…
at -l [-p project] [-q queuename] [at_job_id...]
at -r at_job_id. ..
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 will be 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 will be 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 will be 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 will be 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. It is the equivalent of the command:
at -q b -m now |
In the Trusted Solaris environment, the at and batch commands allow a user to create an at-job file that is installed in the appropriate SLD that matches the invoking process' sensitivity label. The at command also allows a user to list or remove the at-jobs owned by the current user at the invoking process' sensitivity label. A user can list or remove an at-job belonging to another user if the invoking user has the solaris.jobs.admin authorization.
OPTIONS
- -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.
- -P
-
Profile shell. Either pfsh(1M) is used to execute the at-job; or pfksh or pfcsh is used, depending on whether the -s, -k, or -c option is specified.
- -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 current user (or if the current user has the appropriate authorizations, report jobs for other users) at the invoking process's sensitivity label, if no at_job_id operands are specified. If at_job_ids are specified, reports only information for these jobs. If the at-job is not owned by the current user, its job information will be displayed if the invoking user has the solaris.jobs.admin authorization.
- -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 will be mailed to the user as well, unless redirected elsewhere. Mail will be sent even if the job produces no output.
If -m is not used, the job's standard output and standard error will be 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 will be run. When used with the -l option, limits the search to that particular project. Values for project will be 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 will be 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. If the specified at_job_id is not owned by the current user, it is removed if the invoking user has the solaris.jobs.admin authorization.
- -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.
The following options are supported. Note that if a user's login shell is a profile shell, the login shell is used to run the at-job. If the shell is specified with -c, -k,-s, or -P, the specified shell is used. Otherwise, the $SHELL environment variable determines which shell to use. If $SHELL is null, sh is used by default.
OPERANDS
- 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 will submit 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 will be 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
The following operands are supported:
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 |
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 will run 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' |
Example 5 Using the pfcsh shell for an at-job
An example of using the pfcsh shell for an at-job includes:
at -c -P 0815am Jan 24 date |
batch
Example 6 Typical sequence at a terminal
This sequence can be used at a terminal:
$ batch sort <file >outfile <EOT> |
Example 7 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
- SHELL
-
Determine a name of a command interpreter to use to invoke the at-job, when the user's login shell is not pfsh. If the variable is unset or NULL, sh will be used. If it is set to a value other than sh, the implementation will use that shell; a warning diagnostic will be printed telling which shell will be used.
- TZ
-
Determine the timezone. The job will be 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 will override TZ. If timespec does not specify a timezone and TZ is unset or NULL, an unspecified default timezone will be used.
- DATEMSK
-
If the environment variable DATEMSK is set, at will use 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.
See environ(5) for descriptions of the following environment variables that affect the execution of at and batch: LC_CTYPE, LC_MESSAGES, NLSPATH, and LC_TIME.
EXIT STATUS
- 0
-
The at utility successfully submitted, removed or listed a job or jobs.
- >0
-
An error occurred, and the job will not be scheduled.
The following exit values are returned:
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:
at
batch
SUMMARY OF TRUSTED SOLARIS CHANGES
To succeed, the at command requires the following forced privileges: proc_audit_tcb, file_chown, and file_dac_read.
An ancillary file is created in the /var/spool/cron/atjobs directory for each at-job file. By convention, the file is named at_job_id.ad; and it is used by the clock daemon to set up the at-job to run.
The at-jobs are run with the profile shell if the user's login shell is the profile shell. Otherwise, the user's specified shell (by the -c, -s, -k, or -P options), or the $SHELL environment variable (default sh if $SHELL is NULL) is used to run the at-jobs.
SEE ALSO
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 will be 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 | SUMMARY OF TRUSTED SOLARIS CHANGES | SEE ALSO | NOTES
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