1AT(1)                      Linux Programmer's Manual                     AT(1)
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NAME

6       at,  batch,  atq, atrm - queue, examine or delete jobs for later execu‐
7       tion
8

SYNOPSIS

10       at [-V] [-q queue] [-f file] [-mldbv] TIME
11       at [-V] [-q queue] [-f file] [-mldbv] -t time_arg
12       at -c job [job...]
13       atq [-V] [-q queue]
14       atrm [-V] job [job...]
15       batch
16

DESCRIPTION

18       at and batch read commands from standard  input  or  a  specified  file
19       which are to be executed at a later time.
20
21       at      executes commands at a specified time.
22
23       atq     lists  the  user's  pending  jobs, unless the user is the supe‐
24               ruser; in that case, everybody's jobs are listed.   The  format
25               of  the  output  lines (one for each job) is: Job number, date,
26               hour, queue, and username.
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28       atrm    deletes jobs, identified by their job number.
29
30       batch   executes commands when system  load  levels  permit;  in  other
31               words,  when  the  load  average  drops below 0.8, or the value
32               specified in the invocation of atd.
33
34       At allows fairly complex time  specifications,  extending  the  POSIX.2
35       standard.   It  accepts  times of the form HH:MM to run a job at a spe‐
36       cific time of day.  (If that time is already  past,  the  next  day  is
37       assumed.)   You  may  also specify midnight, noon, or teatime (4pm) and
38       you can have a time-of-day suffixed with AM or PM for  running  in  the
39       morning or the evening.  You can also say what day the job will be run,
40       by giving a date in the form month-name day with an optional  year,  or
41       giving a date of the form MMDDYY or MM/DD/YY or DD.MM.YY.  The specifi‐
42       cation of a date must follow the specification of the time of day.  You
43       can  also  give times like now + count time-units, where the time-units
44       can be minutes, hours, days, or weeks and you can tell at  to  run  the
45       job  today by suffixing the time with today and to run the job tomorrow
46       by suffixing the time with tomorrow.
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48       For example, to run a job at 4pm three days from now, you would  do  at
49       4pm  + 3 days, to run a job at 10:00am on July 31, you would do at 10am
50       Jul 31 and to run a job at 1am tomorrow, you would do at 1am tomorrow.
51
52       The exact  definition  of  the  time  specification  can  be  found  in
53       /usr/share/doc/at-3.1.9/timespec.
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55       For  both  at  and  batch, commands are read from standard input or the
56       file specified with the -f option and executed.  The working directory,
57       the  environment (except for the variables TERM, DISPLAY and _) and the
58       umask are retained from the time of invocation.  An at  -  or  batch  -
59       command invoked from a su(1) shell will retain the current userid.  The
60       user will be mailed standard error and standard output  from  his  com‐
61       mands, if any.  Mail will be sent using the command /usr/sbin/sendmail.
62       If at is executed from a su(1) shell, the owner of the login shell will
63       receive the mail.
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65       The  superuser  may  use  these commands in any case.  For other users,
66       permission to use at is  determined  by  the  files  /etc/at.allow  and
67       /etc/at.deny.
68
69       If  the  file  /etc/at.allow exists, only usernames mentioned in it are
70       allowed to use at.
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72       If /etc/at.allow does not exist, /etc/at.deny is checked,  every  user‐
73       name not mentioned in it is then allowed to use at.
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75       If neither exists, only the superuser is allowed use of at.
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77       An  empty  /etc/at.deny means that every user is allowed use these com‐
78       mands, this is the default configuration.
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OPTIONS

81       -V      prints the version number to standard error.
82
83       -q queue
84               uses the specified queue.  A queue designation  consists  of  a
85               single letter; valid queue designations range from a to z.  and
86               A to Z.  The a queue is the default for at and the b queue  for
87               batch.  Queues with higher letters run with increased niceness.
88               The special queue "=" is reserved for jobs which are  currently
89               running.
90
91       If  a  job is submitted to a queue designated with an uppercase letter,
92       the job is treated as if it were submitted to batch at the time of  the
93       job.  Once the time is reached, the batch processing rules with respect
94       to load average apply.  If atq is given a specific queue, it will  only
95       show jobs pending in that queue.
96
97       -m      Send  mail to the user when the job has completed even if there
98               was no output.
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100       -f file Reads the job from file rather than standard input.
101
102       -l      Is an alias for atq.
103
104       -d      Is an alias for atrm.
105
106
107       -v      Shows the time the job will be executed  before  reading
108               the job.
109
110       Times  displayed  will  be  in  the  format "Thu Feb 20 14:50:00
111       1997".
112
113       -c     cats the jobs listed on the command line to standard out‐
114              put.
115
116       -t time_arg
117              Submit  the  job  to  be run at the time specified by the
118              time_arg option argument, which must have the same format
119              as  specified  for  the touch(1) utility's -t time option
120              argument ([[CC]YY]MMDDhhmm).
121

ENVIRONMENT

123       SHELL   The value of the SHELL environment variable at the  time
124               of  at  invocation will determine which shell is used to
125               execute the at job commands. If SHELL is unset  when  at
126               is  invoked, the user's login shell will be used; other‐
127               wise, if SHELL is set when at is invoked, it  must  con‐
128               tain  the  path  of  a shell interpreter executable that
129               will be used to run the commands at the specified time.
130
131       at will record the values of environment  variables  present  at
132       time  of at invocation. When the commands are run at the  speci‐
133       fied time, at will restore these  variables  to  their  recorded
134       values  .  These variables are excluded from this processing and
135       are never set by at when the commands are run :
136       TERM, DISPLAY, SHELLOPTS, _,  PPID,  BASH_VERSINFO,  EUID,  UID,
137       GROUPS.
138       If  the  user submitting the at job is not the super-user, vari‐
139       ables that alter the behaviour of the loader ld.so(8),  such  as
140       LD_LIBRARY_PATH , cannot be recorded and restored by at .
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FILES

143       /var/spool/at
144       /var/spool/at/spool
145       /proc/loadavg
146       /var/run/utmp
147       /etc/at.allow
148       /etc/at.deny
149

SEE ALSO

151       cron(1), nice(1), sh(1), umask(2), atd(8).
152

BUGS

154       The correct operation of batch for Linux depends on the presence
155       of a proc- type directory mounted on /proc.
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157       If the file /var/run/utmp is not available or corrupted,  or  if
158       the user is not logged on at the time at is invoked, the mail is
159       sent to the userid found in the  environment  variable  LOGNAME.
160       If that is undefined or empty, the current userid is assumed.
161
162       At  and  batch  as  presently  implemented are not suitable when
163       users are competing for resources.  If this is the case for your
164       site,  you  might want to consider another batch system, such as
165       nqs.
166

AUTHOR

168       At was  mostly  written  by  Thomas  Koenig,  ig25@rz.uni-karls‐
169       ruhe.de.
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173local                              Nov 1996                              AT(1)
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