1AT(1) Linux Programmer's 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] [-mMlbv] TIME
11 at [-V] [-q queue] [-f file] [-mMlbv] -t time_arg
12 at -c job [job...]
13 at [ -rd ] job [job...]
14 atq [-V] [-q queue]
15 atrm [-V] job [job...]
16 batch
17
19 at and batch read commands from standard input or a specified file
20 which are to be executed at a later time.
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 MMDDYY or MM/DD/YY or DD.MM.YY or YYYY-MM-DD.
43 The specification of a date must follow the specification of the time
44 of day. You can also give times like now + count time-units, where the
45 time-units can be minutes, hours, days, or weeks and you can tell at to
46 run the job today by suffixing the time with today and to run the job
47 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-3.1.10/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 TERM, DISPLAY and _) and the
59 umask are retained from the time of invocation. An at - or batch -
60 command invoked from a su(1) shell will retain the current userid. The
61 user will be mailed standard error and standard output from his com‐
62 mands, if any. Mail will be sent using the command /usr/sbin/sendmail.
63 If at is executed from a su(1) shell, the owner of the login shell will
64 receive the mail.
65 The superuser may use these commands in any case. For other users,
67 permission to use at is determined by the files /etc/at.allow and
68 /etc/at.deny.
69 If the file /etc/at.allow exists, only usernames mentioned in it are
71 allowed to use at.
72 If /etc/at.allow does not exist, /etc/at.deny is checked, every user‐
74 name not mentioned in it is then allowed to use at.
75 If neither exists, only the superuser is allowed use of at.
77 An empty /etc/at.deny means that every user is allowed use these com‐
79 mands, this is the default configuration.
80
82 -V prints the version number to standard error.
83 -q queue
85 uses the specified queue. A queue designation consists of a
86 single letter; valid queue designations range from a to z. and
87 A to Z. The a queue is the default for at and the b queue for
88 batch. Queues with higher letters run with increased niceness.
89 The special queue "=" is reserved for jobs which are currently
90 running.
91 If a job is submitted to a queue designated with an uppercase letter,
93 the job is treated as if it were submitted to batch at the time of the
94 job. Once the time is reached, the batch processing rules with respect
95 to load average apply. If atq is given a specific queue, it will only
96 show jobs pending in that queue.
97 -m Send mail to the user when the job has completed even if there
99 was no output.
100 -M Never send mail to the user.
102 -f file Reads the job from file rather than standard input.
104 -l Is an alias for atq.
106 -r Is an alias for atrm.
108 -d Is an alias for atrm.
110 -v Shows the time the job will be executed before reading
113 the job.
114 Times displayed will be in the format "Thu Feb 20 14:50:00
116 1997".
117 -c cats the jobs listed on the command line to standard out‐
119 put.
120 -t time_arg
122 Submit the job to be run at the time specified by the
123 time_arg option argument, which must have the same format
124 as specified for the touch(1) utility's -t time option
125 argument ([[CC]YY]MMDDhhmm).
126
128 SHELL The value of the SHELL environment variable at the time
129 of at invocation will determine which shell is used to
130 execute the at job commands. If SHELL is unset when at
131 is invoked, the user's login shell will be used; other‐
132 wise, if SHELL is set when at is invoked, it must con‐
133 tain the path of a shell interpreter executable that
134 will be used to run the commands at the specified time.
135 at will record the values of environment variables present at
137 time of at invocation. When the commands are run at the speci‐
138 fied time, at will restore these variables to their recorded
139 values . These variables are excluded from this processing and
140 are never set by at when the commands are run :
141 TERM, DISPLAY, SHELLOPTS, _, PPID, BASH_VERSINFO, EUID, UID,
142 GROUPS.
143 If the user submitting the at job is not the super-user, vari‐
144 ables that alter the behaviour of the loader ld.so(8), such as
145 LD_LIBRARY_PATH , cannot be recorded and restored by at .
146
148 /var/spool/at
149 /var/spool/at/spool
150 /proc/loadavg
151 /var/run/utmp
152 /etc/at.allow
153 /etc/at.deny
154
156 cron(1), nice(1), sh(1), umask(2), atd(8).
157
159 The correct operation of batch for Linux depends on the presence
160 of a proc- type directory mounted on /proc.
161 If the file /var/run/utmp is not available or corrupted, or if
163 the user is not logged on at the time at is invoked, the mail is
164 sent to the userid found in the environment variable LOGNAME.
165 If that is undefined or empty, the current userid is assumed.
166 At and batch as presently implemented are not suitable when
168 users are competing for resources. If this is the case for your
169 site, you might want to consider another batch system, such as
170 nqs.
171
173 At was mostly written by Thomas Koenig, ig25@rz.uni-karls‐
174 ruhe.de.
175local Nov 1996 AT(1)