HPUX at[1]
at(1) at(1)
NAME
at, batch - execute commands at a later time
SYNOPSIS
at [-m] [-ffilename] [-qqueue] time [date] [[next | +increment]
time_designation] job ...
at -r job_id ...
at -l [job_id ...]
batch
DESCRIPTION
at, in the first form shown above, and batch read commands from
standard input to be executed at a later time:
at Executes commands at a specified time.
batch Executes commands when system load level permits.
In the second and third forms, at respectively removes one or more
currently scheduled jobs, or lists some or all currently scheduled
jobs.
An at_job consists of one or more executable commands exectuable by
the shell. at creates a shell script in /usr/spool/cron/atjobs, the
first part of which sets up the environment to match that of the
invoking user. The second part of the script consists of the commands
entered by the user. When cron dispatches the job it execs a shell to
execute the command file (script).
Options
at recognizes the following options and command-line arguments where
job is any valid HP-UX command:
-l [job_id ...]
List all jobs currently scheduled for the invoking
user. If job_ids are given, only the specified jobs
are listed.
-r job_id ...
Remove the jobs with the specified job_ids that were
previously scheduled by the at command. Job_id is
the job number assigned by at when the job was
originally scheduled. When removing multiple jobs,
use blanks to separate job_ids.
-m Send mail to the invoking user after the job has run,
announcing its completion. Standard output and
standard error produced by the job are mailed to the
user as well, unless they were redirected elsewhere
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within the job.
-ffilename Specify the pathname of a file to be used as the
source of the job, instead of standard input.
-qqueue Submit the specified job to the queue indicated (see
queuedefs(4)). Queues a, b, and d through y can be
used. at uses queue a by default. All queues
require a time designation except queue b which runs
as soon as system load level permits. Queue b is
reserved for use by the batch command.
time Can be specified as one, two, or four digits. One-
and two-digit numbers represent hours; four digits
represent hours and minutes. Alternately, time can
be specified as two numbers separated by a colon (:),
single quote ('), the letter "h" (h), a period (.),
or comma (,). If defined in langinfo(3C), special
time unit characters can be used. A suffix am or pm
can be appended. Otherwise a 24-hour clock time is
understood. For example, 8:15, 8'15, 8h15, 8.15, and
8,15 are read as 15 minutes after 8 in the morning.
The suffixes zulu and utc can be used to indicate
Coordinated Universal Time. The special names noon,
midnight, now, and next are also recognized.
date (optional) Can be specified as either a day of the
week (fully spelled out or abbreviated) or a date
consisting of a day, a month, and optionally a year.
The day and year fields must be numeric, and the
month can be either fully spelled out, abbreviated,
or numeric. These three fields can be in any order,
and separated by punctuation marks such as /, -, .,
or ,. If defined in langinfo(3C), special date unit
characters can be present. Two special ``days'',
today and tomorrow, are also recognized. If no date
is given, today is assumed if the given time is
greater than the current time; 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. If a given date is ambiguous (such as 2/5),
the D_T_FMT string (if defined in langinfo(3C)) is
used to resolve the ambiguity.
next (optional) If followed by a time_designation of
or minutes, hours, days, weeks, months, or years, lets
+increment the user schedule a task to be executed when the
specified time_designation has elapsed. A numerical
operator, +increment, enables the user to schedule
the task several hours, days, weeks, months, or years
in advance (see EXAMPLES). Using the argument next
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is equivalent to using an increment of +1. Both
plural and singular forms of time_designation are
accepted.
Standard output and standard error output are mailed to the user
unless they are redirected elsewhere. The shell environment
variables, current directory, umask (see umask(1)) and ulimit (see
ulimit(2)) are retained when the commands are executed (see proto(4)).
Open file descriptors, traps, and priority are lost.
Only users whose names appear in file /usr/lib/cron/at.allow can run
at. If that file does not exist, file /usr/lib/cron/at.deny is
checked to determine if the user should be denied access to at. If
neither file exists, only root is allowed to submit a job. If only
at.deny exists but is empty, global usage is permitted. The
allow/deny files consist of one user name per line.
The words today, tomorrow, noon, midnight, now, minutes, hours, days,
weeks, months, years and their singular forms are replaced by the
local language equivalent (see EXTERNAL INFLUENCES below).
at and batch write the job_id and schedule time to standard error.
batch submits a batch job. It is similar to at now, but with the
following differences: batch goes into a different queue; at now
responds with error messages.
at -r removes jobs previously scheduled by at or batch. The job_id is
the number returned by the at or batch command. To get job numbers,
typing at -l. Only users with appropriate privileges can remove jobs
other than their own.
EXTERNAL INFLUENCES
Environment Variables
LC_TIME determines the format and contents of date and time strings.
LANG determines the translation of the words today, tomorrow, noon,
midnight, now, minutes, hours, days, weeks, months, years, next, and
their singular forms. LANG also determines the language in which
messages are displayed.
If LC_TIME is not specified in the environment or is set to the empty
string, the value of LANG is used as a default for each unspecified or
empty variable. If LANG is not specified or is set to the empty
string, a default of "C" (see lang(5)) is used instead of LANG. If
any internationalization variable contains an invalid setting, at
behaves as if all internationalization variables are set to "C". See
IR environ(5).
International Code Set Support
Single- and multi-byte character code sets are supported.
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RETURN VALUE
Exit code 0 is returned upon successful completion, otherwise 1 is
returned.
DIAGNOSTICS
at complains about syntax errors and out-of-range times.
If login shell is not /bin/sh, at produces a warning message as a
reminder that at jobs are executed using /bin/sh.
EXAMPLES
The at and batch commands read from standard input the commands to be
executed at a later time, unless the -f option is specified. sh(1)
provides different ways of specifying standard input. Within your
commands, it may be useful to redirect standard output.
The following sequence can be used at a terminal to redirect output:
batch
nroff filename > outfile
<Ctrl-D>
This sequence demonstrates redirecting standard error to a pipe and is
useful in a shell procedure. Note that the sequence of output
redirection specifications is significant:
batch <<!
nroff filename 2>&1 > outfile | mail loginid
!
To perform a task at 5:00 am next Tuesday, use
at 5am tuesday next week
To perform a task at 5:00 am one week from Tuesday (that is, 2
Tuesdays in advance) use
at 5am tuesday + 2 weeks
To have a job reschedule itself, invoke at from within the shell
procedure by including code similar to the following within the shell
file:
echo "sh shellfile" | at 1900 thursday next week
The following commands show several forms recognized by at and include
native language usage:
at 0815 Jan 24
at 8:15 Jan 24
at 9:30am tomorrow
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at now + 1 day
at -f job 5 pm Friday
at 17:40 Tor. /* in Danish */
at 17h46 demain /* in French */
at 5:30 26. Feb. 1988 /* in German */
at 12:00 26-02 /* in Finnish */
WARNINGS
If the date argument begins with a number and the time argument is
also numeric without suffix, the time argument should be a four-digit
number that can be correctly interpreted as hours and minutes.
Do not use both next and + increment within a single at command; only
the first operator is accepted and the trailing operator is ignored.
No warning or error is produced.
If the FIFO used to communicate with cron fills up, at is suspended
until cron has read sufficient messages from the FIFO to make room for
the message at is trying to write. This condition can occur if at is
writing messages faster than cron can process them or if cron is not
executing.
AUTHOR
at was developed by AT&T and HP.
FILES
/usr/lib/cron main cron directory
/usr/lib/cron/at.allow list of allowed users
/usr/lib/cron/at.deny list of denied users
/usr/spool/cron/atjobs spool area
/usr/lib/cron/queuedefs scheduling information
/usr/lib/cron/.proto prototype information
SEE ALSO
cron(1M), crontab(1), queuedefs(4), proto(4), kill(1), mail(1),
nice(1), ps(1), sh(1), hpnls(5).
STANDARDS CONFORMANCE
at: SVID2, XPG2, XPG3
batch: SVID2, XPG2, XPG3
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