1AT(1) General Commands Manual AT(1)
2
6 at, batch, atq, atrm - queue, examine or delete jobs for later execu‐
7 tion
8
10 at [-V] [-q queue] [-f file] [-mldv] timespec...
11 at [-V] [-q queue] [-f file] [-mkdv] [-t time]
12 at -c job [job...]
13 atq [-V] [-q queue]
14 atrm [-V] job [job...]
15 batch
16 at -b
17
19 at and batch read commands from standard input or a specified file
20 which are to be executed at a later time, using /bin/sh.
21 at executes commands at a specified time.
23 atq lists the user's pending jobs, unless the user is the supe‐
25 ruser; in that case, everybody's jobs are listed. The format
26 of the output lines (one for each job) is: Job number, date,
27 hour, queue, and username.
28 atrm deletes jobs, identified by their job number.
30 batch executes commands when system load levels permit; in other
32 words, when the load average drops below 0.8, or the value
33 specified in the invocation of atd.
34 At allows fairly complex time specifications, extending the POSIX.2
36 standard. It accepts times of the form HH:MM to run a job at a spe‐
37 cific time of day. (If that time is already past, the next day is
38 assumed.) You may also specify midnight, noon, or teatime (4pm) and
39 you can have a time-of-day suffixed with AM or PM for running in the
40 morning or the evening. You can also say what day the job will be run,
41 by giving a date in the form month-name day with an optional year, or
42 giving a date of the form MMDD[CC]YY, MM/DD/[CC]YY, DD.MM.[CC]YY or
43 [CC]YY-MM-DD. The specification of a date must follow the specifica‐
44 tion of the time of day. You can also give times like now + count
45 time-units, where the time-units can be minutes, hours, days, or weeks
46 and you can tell at to run the job today by suffixing the time with
47 today and to run the job tomorrow by suffixing the time with tomorrow.
48 For example, to run a job at 4pm three days from now, you would do at
50 4pm + 3 days, to run a job at 10:00am on July 31, you would do at 10am
51 Jul 31 and to run a job at 1am tomorrow, you would do at 1am tomorrow.
52 The exact definition of the time specification can be found in
54 /usr/share/doc/at-3.1.12/timespec.
55 For both at and batch, commands are read from standard input or the
57 file specified with the -f option and executed. The working directory,
58 the environment (except for the variables BASH_VERSINFO, DISPLAY, EUID,
59 GROUPS, SHELLOPTS, TERM, UID, and _) and the umask are retained from
60 the time of invocation.
61 As at is currently implemented as a setuid program, other environment
63 variables (e.g. LD_LIBRARY_PATH or LD_PRELOAD) are also not exported.
64 This may change in the future. As a workaround, set these variables
65 explicitly in your job.
66 An at - or batch - command invoked from a su(1) shell will retain the
68 current userid. The user will be mailed standard error and standard
69 output from his commands, if any. Mail will be sent using the command
70 /usr/sbin/sendmail. If at is executed from a su(1) shell, the owner of
71 the login shell will receive the mail.
72 The superuser may use these commands in any case. For other users,
74 permission to use at is determined by the files /etc/at.allow and
75 /etc/at.deny.
76 If the file /etc/at.allow exists, only usernames mentioned in it are
78 allowed to use at.
79 If /etc/at.allow does not exist, /etc/at.deny is checked, every user‐
81 name not mentioned in it is then allowed to use at.
82 If neither exists, only the superuser is allowed use of at.
84 An empty /etc/at.deny means that every user is allowed use these com‐
86 mands, this is the default configuration.
87
89 -V prints the version number to standard error and exit success‐
90 fully.
91 -q queue
93 uses the specified queue. A queue designation consists of a
94 single letter; valid queue designations range from a to z. and
95 A to Z. The a queue is the default for at and the b queue for
96 batch. Queues with higher letters run with increased niceness.
97 The special queue "=" is reserved for jobs which are currently
98 running.
99 If a job is submitted to a queue designated with an uppercase
101 letter, the job is treated as if it were submitted to batch at
102 the time of the job. Once the time is reached, the batch pro‐
103 cessing rules with respect to load average apply. If atq is
104 given a specific queue, it will only show jobs pending in that
105 queue.
106 -m Send mail to the user when the job has completed even if there
108 was no output.
109 -f file Reads the job from file rather than standard input.
111 -t time run the job at time, given in the format [[CC]YY]MMDDhhmm[.ss]
113 -l Is an alias for atq.
115 -d Is an alias for atrm.
117 -b is an alias for batch.
119 -v Shows the time the job will be executed before reading the job.
121 Times displayed will be in the format "Thu Feb 20 14:50:00
123 1997".
124 -c cats the jobs listed on the command line to standard output.
126
128 /var/spool/at
129 /var/spool/at/spool
130 /proc/loadavg
131 /var/run/utmp
132 /etc/at.allow
133 /etc/at.deny
134
136 cron(1), nice(1), sh(1), umask(2), atd(8).
137
139 The correct operation of batch for Linux depends on the presence of a
140 proc- type directory mounted on /proc.
141 If the file /var/run/utmp is not available or corrupted, or if the user
143 is not logged on at the time at is invoked, the mail is sent to the
144 userid found in the environment variable LOGNAME. If that is undefined
145 or empty, the current userid is assumed.
146 At and batch as presently implemented are not suitable when users are
148 competing for resources. If this is the case for your site, you might
149 want to consider another batch system, such as nqs.
150
152 At was mostly written by Thomas Koenig, ig25@rz.uni-karlsruhe.de.
153 2009-11-14 AT(1)