HP-UX Reference (11i v2 04/09) - 1 User Commands A-M (vol 1)

a
at(1) at(1)
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 ambiguity.
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. Two-digit years in the range 69 to 99
are expanded to 1969 to 1999; in the range 00 to 68, to 2000 to
2068.
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,oryears, or their singular forms.
How Jobs Are Processed
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
-q option.
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.
The second part consists of the commands that you entered.
When
cron dispatches the job, it starts a POSIX shell to execute the script.
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 else-
where 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
Environment Variables
LC_TIME determines the format and contents of date and time strings.
LC_MESSAGES determines the language in which messages are displayed.
HP-UX 11i Version 2: September 2004 − 3 − Hewlett-Packard Company Section 1−−37