AT(1)

AT(1) | General Commands Manual | AT(1)

# NAME

`at`, `batch`, `atq`, `atrm` —
queue, examine or delete jobs for later execution

# SYNOPSIS

`at` | [`-bdlmrVv`] [`-f` file] [`-q` queue] `-t` [[CC]YY]MMDDhhmm[.SS]

`at` | [`-bdlmrVv`] [`-f` file] [`-q` queue] time

`at` | [`-V`] `-c` job [job ...]

`atq` | [`-Vv`] [`-q` queue]

`atrm` | [`-V`] job [job ...]

`batch` | [`-mVv`] [`-f` file] [`-q` queue] [`-t` [[CC]YY]MMDDhhmm[.SS]]

`batch` | [`-mVv`] [`-f` file] [`-q` queue] [time]

# DESCRIPTION

`at` and `batch` read commands from standard input or a specified file which are to be executed at a later time, using sh(1).

`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.
`atrm`
  Deletes jobs.
`batch`
  Executes commands when system load levels permit. In other words, when the load average drops below 1.5, or the value specified in the invocation of atrun(8).

`at` allows some moderately complex time specifications. It accepts times of the form HHMM or 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`] or [`now`] ‘+ count %time-units’, where the time-units can be ‘minutes’, ‘hours’, ‘days’, ‘weeks’, ‘months’, or ‘years’ 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.`

Alternatively the time may be specified in a language-neutral fashion by using the `-t` options.

For both `at` and `batch`, commands are read from standard input or the file specified with the `-f` option and executed. The working directory, the environment (except for the variables `TERM`, `TERMCAP`, `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 standard output from his commands, if any. Mail will be sent using the command sendmail(1). 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 /var/at/at.allow and /var/at/at.deny.

If the file /var/at/at.allow exists, only usernames mentioned in it are allowed to use `at`.

If /var/at/at.allow does not exist, /var/at/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 /var/at/at.deny means that every user is allowed use these commands. This is the default configuration.

# OPTIONS

`-b`
  Is an alias for `batch`.
`-c`
  Cats the jobs listed on the command line to standard output.
`-d`
  Is an alias for `atrm`.
`-f` file
  Reads the job from file rather than standard input.
`-l`
  Is an alias for `atq`.
`-m`
  Send mail to the user when the job has completed even if there was no output.
`-q` queue
  Uses the specified queue. A queue designation consists of a single letter. Valid queue designations range from ‘a’ to ‘z’ and ‘A’ to ‘Z’. The ‘c’ queue is the default for `at` and the ‘E’ queue for `batch`. Queues with higher letters run with increased niceness. If a job is submitted to a queue designated with an uppercase 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.
`-r`
  Is an alias for `atrm`.
`-t`
  For both `at` and `batch`, the time may be specified in a language-neutral format consisting of:
  CC
    The first two digits of the year (the century).
  YY
    The second two digits of the year. If YY is specified, but CC is not, a value for YY between 69 and 99 results in a CC value of 19. Otherwise, a CC value of 20 is used.
  MM
    The month of the year, from 01 to 12.
  DD
    The day of the month, from 01 to 31.
  hh
    The hour of the day, from 00 to 23.
  mm
    The minute of the hour, from 00 to 59.
  SS
    The second of the minute, from 00 to 61.
`-V`
  Prints the version number to standard error.
`-v`
  For `atq`, shows completed but not yet deleted jobs in the queue. Otherwise shows the time the job will be executed.

# FILES

/var/at/jobs
  Directory containing job files
/var/at/spool
  Directory containing output spool files
/var/run/utmp
  Login records
/var/at/at.allow
  Allow permission control
/var/at/at.deny
  Deny permission control
/var/at/.lockfile
  Job-creation lock file.

# SEE ALSO

nice(1), sendmail(1), sh(1), umask(2), atrun(8), cron(8)

# STANDARDS

The `at` and `batch` utilities conform to IEEE Std 1003.2-1992 (“POSIX.2”).

# AUTHORS

`at` was mostly written by Thomas Koenig <ig25@rz.uni-karlsruhe.de>. The time parsing routines are implemented by David Parsons <orc@pell.chi.il.us>.

# BUGS

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 current 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`.

March 10, 2008 | NetBSD 9.3