NAME [Toc] [Back]
at, batch - execute batched commands immediately or at a later time
SYNOPSIS [Toc] [Back]
Enter commands from standard input to run at a specified time:
at [-m] [-q queue] -t spectime
at [-m] [-q queue] time [date]
[next timeunit | +count timeunit]
Enter commands from a file to run at a specified time:
at -f job-file [-m] [-q queue] -t spectime
at -f job-file [-m] [-q queue] time [date]
[next timeunit | +count timeunit]
List scheduled jobs:
at -d job-id ...
at -l [job-id ...]
at -l -q queue
Cancel (remove) a scheduled job:
at -r job-id ...
Enter commands from standard input to run as a batch process:
Enter commands from a file to run as a batch process:
batch < job-file
DESCRIPTION [Toc] [Back]
The at and batch commands schedule jobs for execution by the cron
daemon (see cron(1M)).
at schedules a job for execution at a specified time. at can also
list (-l) or remove (-r) existing scheduled at and batch jobs.
batch schedules a job for execution immediately, or as soon as system
load levels permit.
You can enter commands into a job in one of the following ways:
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+ From the keyboard on separate lines immediately after the at or
batch command line, followed by the currently defined eof (endof-file)
character to end the input. The default eof is Ctrl-D.
It can be redefined in your environment (see stty(1)).
+ With the -f option of the at command to read input from a script
+ From output piped from a preceding command.
Options and Arguments [Toc] [Back]
at recognizes the following options and arguments.
commands One or more HP-UX commands that can be
executed as a shell script by at or batch.
eof End-of-file character. The default is Ctrl-D
unless defined otherwise in your environment.
job-file The path name of an existing file.
job-id The job identifier reported by at or batch
when the job was originally scheduled.
-d job-id ... Displays the contents of the specified job.
An unprivileged user is restricted to display
information only on jobs that the user owns.
A user with the appropriate privileges is
able to display information about all jobs.
-f job-file Read in the commands contained in job-file
instead of using standard input.
-l [job-id ...] List the jobs specified. If no job-ids are
given, all jobs are listed.
-m Send mail to the invoking user after the job
has run, announcing its completion. Unless
redirected elsewhere within the job, standard
output and standard error produced by the job
are automatically mailed to the user as well.
-q queue 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. batch always uses queue b. All
queues except b require a time or a -t
specification. at -qb is equivalent to
batch. When used with the -l option, limit
the search to that particular queue.
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-r job-id ... Remove the jobs specified by each job-id.
-t spectime Define the absolute time to start the job.
spectime A date and time in the format:
[[CC]YY]MMDDhhmm [ . ss ]
where the decimal digit pairs are
CC The first two digits of the
year (19, 20).
YY The second two digits of the
year (69-99, 00-68). See
MM The month of the year (01-12).
DD The day of the month (01-31).
hh The hour of the day (00-23).
mm The minute of the hour
ss The second of the minute
If both CC and YY are omitted, the
default is the current year.
If CC is omitted and YY is in the
range 69-99, CC defaults to 19.
Otherwise, CC defaults to 20.
The range for ss provides for two
leap seconds. If ss is 60 or 61,
and the resulting time, as affected
by the TZ environment variable,
does not refer to a leap second,
the time is set to the whole minute
If ss is omitted, it defaults to
time [date] Define the base time for starting the job.
time A time 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
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(:), a single quote ('), the letter
h (h), a period (.), or a comma
(,). Spaces may be present between
the separator and digits
representing minutes. If defined
in langinfo(5), special time unit
characters can be used.
am or pm can be appended to
indicate morning or afternoon.
Otherwise, a 24-hour clock is
understood. For example, 0815,
8:15, 8'15, 8h15, 8.15, and 8,15
are read as 15 minutes after eight
in the morning. The suffixes zulu
and utc can be used to specify
Coordinated Universal Time (UTC),
equivalent to Greenwich Mean Time
The special names midnight, noon,
and now are also recognized.
date 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. The fields in the date
string are separated by punctuation
marks such as slash (/), hyphen (-
), period (.), and comma (,). If
defined in langinfo(5), special
date unit characters can be
present. A field having a value
greater than 31 is treated as the
year field and the remaining two
fields in the date string are
treated as month and day fields.
Otherwise, if a given date is
ambiguous (such as 2/5 or 2/5/10),
the D_T_FMT string (if defined in
langinfo(5)) is used to resolve the
Two special days, today and
tomorrow, are also recognized. If
no date is given, today is assumed
if the given time is greater than
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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.
Two-digit years in the range 69 to
99 are expanded to 1969 to 1999; in
the range 00 to 68, to 2000 to
next timeunit | + count timeunit
Delay the execution date and time by a
specific number of time units after the base
time specified by time [date].
count A decimal number. next is
equivalent to +1.
timeunit A time unit, one of the following:
minutes, hours, days, weeks,
months, or years, or their singular
How Jobs Are Processed [Toc] [Back]
When a job is accepted, at and batch print a message to standard error
in the form:
job job-id at execution-date
where job-id is the job identifier in the form jobnumber.queue, such
as 756284400.a, and execution-date is the date and time when the job
will be released for execution.
If your login shell is not the POSIX shell (/usr/bin/sh), the commands
also print a warning message:
warning: commands will be executed using /usr/bin/sh
at jobs default to queue a. batch jobs always go in queue b. See the
An at or batch job consists of a two-part script stored in
/var/spool/cron/atjobs that can be executed by the POSIX shell.
The first part sets up the environment to match the environment when
the at or batch command was issued. This includes the current shell
environment variables, current directory, umask, and ulimit (see
ulimit(2), umask(1), and proto(4)). Open file descriptors, traps, and
priority are lost.
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The second part consists of the commands that you entered.
When cron dispatches the job, it starts a POSIX shell to execute the
The number of jobs executing from a queue at any time is controlled by
parameters in the file /var/adm/cron/queuedefs (see queuedefs(4)).
Standard output and standard error from the job are mailed to the user
unless they are redirected elsewhere within the job.
Scheduled jobs are immune to the SIGHUP hangup signal, and remain
scheduled if the user logs off.
Users are permitted to use the at and batch commands if their user
names appear in the file /usr/lib/cron/at.allow. If that file does
not exist, users can use at and batch if their names do not appear in
the file /usr/lib/cron/at.deny. If neither file exists, only
superuser is allowed to submit jobs. If only at.deny exists but is
empty, all users can use at and batch. The allow/deny files consist
of one user name per line.
All users can list and remove their own jobs. Users with appropriate
privileges can list and remove jobs other than their own.
EXTERNAL INFLUENCES [Toc] [Back]
LC_TIME determines the format and contents of date and time strings.
LC_MESSAGES determines the language in which messages are displayed.
LC_MESSAGES also determines the language in which the words days,
hours, midnight, minutes, months, next, noon, now, today, tomorrow,
weeks, years, and their singular forms can also be specified.
IF LC_TIME or LC_MESSAGES 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, all
internationalization variables default to "C" (see environ(5)).
International Code Set Support [Toc] [Back]
Single- and multi-byte character code sets are supported.
Notes [Toc] [Back]
The batch command requests a unique job-id for each batch job it
schedules. The maximum number of tries to request a unique job-id is
restricted to 100. If not successful after 100 tries, the batch
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command exist with the message queue full. If the BatchConfig product
is installed, you can configure this number by setting the variable
BATCH_MAXTRYS=value in the /etc/default/cron file. The value of
BATCH_MAXTRYS can be any positive number or the string INFINITE (the
default value). If the value is set to INFINITE, batch requests a
unique job-id until it successfully receives one.
RETURN VALUE [Toc] [Back]
The exit code is set to one of the following:
0 Successful completion
DIAGNOSTICS [Toc] [Back]
at produces self-explanatory messages for syntax errors and out-ofrange
warning: commands will be executed using /usr/bin/sh
If your login shell is not the POSIX shell (/usr/bin/sh), at and
batch produce a warning message as a reminder that at and batch
jobs are executed using /usr/bin/sh.
EXAMPLES [Toc] [Back]
The following commands show three different ways to run a POSIX shell
script file named delayed-job five minutes from now:
at -f delayed-job now + 5 minutes
cat delayed-job | at now + 5 minutes
at now + 5 minutes <delayed-job
Run a typical HP-UX command (nroff in this case) when system load
levels permit, and redirect standard output and standard error to
nroff source-file >output-file 2>error-file
eof (the default is Ctrl-D)
Run a job contained in future in the home directory at 12:20 a.m. on
December 27, 2013:
at -f $HOME/future -t201312271220.00
Redirect standard error to a pipe (useful in a shell procedure). Note
that the sequence of the output redirection specifications is
significant. Standard error is redirected to where standard output is
going; standard output is redirected to a file; the original "standard
output" (which now consists of the former standard error) is piped to
the mail program.
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batch <<!! (sets eof temporarily to !!)
nroff input-file 2>&1 1> output-file | mail loginid
Run a job contained in jobfile in the home directory at 5:00 a.m. next
at -f $HOME/jobfile 5am tuesday next week
Run the same job at 5:00 a.m. one week from next Tuesday (i.e., 2
Tuesdays in advance):
at -f $HOME/jobfile 5am tuesday + 2 weeks
Add a command to the file named weekly-run in directory jobs in the
home directory so that it automatically reschedules itself every time
it runs. This example reschedules itself every Thursday at 1900 (7:00
echo "sh $HOME/jobs/weekly-run" | 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
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 [Toc] [Back]
If the date argument begins with a number and the time argument is
also numeric without a suffix, the time argument should be a fourdigit
number that can be correctly interpreted as hours and minutes.
If you use both next and +count within a single at command, the first
operator is accepted and the trailing operator is silently ignored.
If you use both -t and time ... in the same command, the first
specified is accepted and the second is silently ignored.
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
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Scheduled processes are run in the background. Any script file that
calls itself will cause the user or the system to run out of available
If the execution-time request for a job duplicates the execution time
of a currently scheduled job, the new job time is set to the next
at will not schedule jobs whose start time precedes the current Epoch
(00:00:00 January 1, 1970 UTC). at will not schedule jobs beyond the
DEPENDENCIES [Toc] [Back]
HP Process Resource Manager
If the optional HP Process Resource Management (PRM) software is
installed and configured, jobs are launched in the initial process
resource group of the user that scheduled the job. The user's initial
group is determined at the time the job is started, not when the job
is scheduled. If the user's initial group is not defined, the job
runs in the user default group (PRMID=1). See prmconfig(1) for a
description of how to configure HP PRM, and prmconf(4) for a
description of how the user's initial process resource group is
AUTHOR [Toc] [Back]
at was developed by AT&T and HP.
FILES [Toc] [Back]
/usr/bin/sh POSIX shell
/var/adm/cron Main cron directory
/var/adm/cron/.proto This file contains a set of shell
commands which are added to the at
job file to make the environment
for the at job same as the current
environment. See proto(4).
/usr/lib/cron/at.allow List of allowed users
/usr/lib/cron/at.deny List of denied users
/var/adm/cron/queuedefs Scheduling information
/var/spool/cron/atjobs Spool area
SEE ALSO [Toc] [Back]
crontab(1), kill(1), mail(1), nice(1), ps(1), sh(1), stty(1),
cron(1M), proto(4), queuedefs(4).
HP Process Resource Manager: prmconfig(1), prmconf(4) in HP Process
Resource Manager User's Guide.
STANDARDS CONFORMANCE [Toc] [Back]
at: SVID2, SVID3, XPG2, XPG3, XPG4
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batch: SVID2, SVID3, XPG2, XPG3, XPG4
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