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1 .\" $NetBSD: at.1,v 1.23 2008/03/11 01:04:18 christos Exp $
2 .\" $OpenBSD: at.1,v 1.6 1998/06/05 00:47:46 deraadt Exp $
3 .\" $FreeBSD: at.man,v 1.6 1997/02/22 19:54:05 peter Exp $
4 .Dd March 10, 2008
5 .Dt AT 1
6 .Os
7 .Sh NAME
8 .Nm at ,
9 .Nm batch ,
10 .Nm atq ,
11 .Nm atrm
12 .Nd queue, examine or delete jobs for later execution
13 .Sh SYNOPSIS
14 .Nm at
15 .Op Fl bdlmrVv
16 .Op Fl f Ar file
17 .Op Fl q Ar queue
18 .Fl t Ar [[CC]YY]MMDDhhmm[.SS]
19 .Nm
20 .Op Fl bdlmrVv
21 .Op Fl f Ar file
22 .Op Fl q Ar queue
23 .Ar time
24 .Nm
25 .Op Fl V
26 .Fl c Ar job Op Ar job ...
27 .Nm atq
28 .Op Fl Vv
29 .Op Fl q Ar queue
30 .Nm atrm
31 .Op Fl V
32 .Ar job
33 .Op Ar job ...
34 .Nm batch
35 .Op Fl mVv
36 .Op Fl f Ar file
37 .Op Fl q Ar queue
38 .Op Fl t Ar [[CC]YY]MMDDhhmm[.SS]
39 .Nm batch
40 .Op Fl mVv
41 .Op Fl f Ar file
42 .Op Fl q Ar queue
43 .Op Ar time
44 .Sh DESCRIPTION
45 .Nm
46 and
47 .Nm batch
48 read commands from standard input or a specified file which
49 are to be executed at a later time, using
50 .Xr sh 1 .
51 .Bl -tag -width indent
52 .It Nm at
53 Executes commands at a specified time.
54 .It Nm atq
55 Lists the user's pending jobs, unless the user is the superuser.
56 In that case, everybody's jobs are listed.
57 .It Nm atrm
58 Deletes jobs.
59 .It Nm batch
60 Executes commands when system load levels permit.
61 In other words, when
62 the load average drops below 1.5, or the value specified in the invocation of
63 .Xr atrun 8 .
64 .El
65 .Pp
66 .Nm
67 allows some moderately complex
68 .Ar time
69 specifications.
70 It accepts times of the form
71 .Ar HHMM
72 or
73 .Ar HH:MM
74 to run a job at a specific time of day.
75 (If that time is already past, the next day is assumed.)
76 You may also specify
77 .Sq midnight ,
78 .Sq noon ,
79 or
80 .Sq teatime
81 (4pm)
82 and you can have a time-of-day suffixed with
83 .Sq AM
84 or
85 .Sq PM
86 for running in the morning or the evening.
87 You can also say what day the job will be run,
88 by giving a date in the form
89 .Ar %month-name day
90 with an optional
91 .Ar year ,
92 or giving a date of the form
93 .Ar MMDDYY
94 or
95 .Ar MM/DD/YY
96 or
97 .Ar DD.MM.YY .
98 The specification of a date must follow the specification of
99 the time of day.
100 You can also give times like
101 .Op Nm now
102 or
103 .Op Nm now
104 .Sq + Ar count %time-units ,
105 where the time-units can be
106 .Sq minutes ,
107 .Sq hours ,
108 .Sq days ,
109 .Sq weeks,
110 .Sq months,
111 or
112 .Sq years
113 and you can tell
114 .Nm
115 to run the job today by suffixing the time with
116 .Sq today
117 and to run the job tomorrow by suffixing the time with
118 .Sq tomorrow .
119 .Pp
120 For example, to run a job at 4pm three days from now, you would do
121 .Dl at 4pm + 3 days ,
122 to run a job at 10:00am on July 31, you would do
123 .Dl at 10am Jul 31
124 and to run a job at 1am tomorrow, you would do
125 .Dl at 1am tomorrow .
126 .Pp
127 Alternatively the time may be specified in a language-neutral fashion
128 by using the
129 .Fl t
130 options.
131 .Pp
132 For both
133 .Nm
134 and
135 .Nm batch ,
136 commands are read from standard input or the file specified
137 with the
138 .Fl f
139 option and executed.
140 The working directory, the environment (except for the variables
141 .Ev TERM ,
142 .Ev TERMCAP ,
143 .Ev DISPLAY
144 and
145 .Ev _ )
146 and the
147 .Ar umask
148 are retained from the time of invocation.
149 An
150 .Nm
151 or
152 .Nm batch
153 command invoked from a
154 .Xr su 1
155 shell will retain the current userid.
156 The user will be mailed standard error and standard output from his
157 commands, if any.
158 Mail will be sent using the command
159 .Xr sendmail 8 .
160 If
161 .Nm
162 is executed from a
163 .Xr su 1
164 shell, the owner of the login shell will receive the mail.
165 .Pp
166 The superuser may use these commands in any case.
167 For other users, permission to use at is determined by the files
168 .Pa /var/at/at.allow
169 and
170 .Pa /var/at/at.deny .
171 .Pp
172 If the file
173 .Pa /var/at/at.allow
174 exists, only usernames mentioned in it are allowed to use
175 .Nm .
176 .Pp
177 If
178 .Pa /var/at/at.allow
179 does not exist,
180 .Pa /var/at/at.deny
181 is checked, every username not mentioned in it is then allowed
182 to use
183 .Nm .
184 .Pp
185 If neither exists, only the superuser is allowed use of
186 .Nm .
187 .Pp
188 An empty
189 .Pa /var/at/at.deny
190 means that every user is allowed use these commands.
191 This is the default configuration.
192 .Sh OPTIONS
193 .Bl -tag -offset indent -width XqXqueueXX
194 .It Fl b
195 Is an alias for
196 .Nm batch .
197 .It Fl c
198 Cats the jobs listed on the command line to standard output.
199 .It Fl d
200 Is an alias for
201 .Nm atrm .
202 .It Fl f Ar file
203 Reads the job from
204 .Ar file
205 rather than standard input.
206 .It Fl l
207 Is an alias for
208 .Nm atq .
209 .It Fl m
210 Send mail to the user when the job has completed even if there was no
211 output.
212 .It Fl q Ar queue
213 Uses the specified queue.
214 A queue designation consists of a single letter.
215 Valid queue designations
216 range from
217 .Sq a
218 to
219 .Sq z
220 and
221 .Sq A
222 to
223 .Sq Z .
224 The
225 .Sq c
226 queue is the default for
227 .Nm
228 and the
229 .Sq E
230 queue for
231 .Nm batch .
232 Queues with higher letters run with increased niceness.
233 If a job is submitted to a queue designated with an uppercase letter, it
234 is treated as if it had been submitted to batch at that time.
235 If
236 .Nm atq
237 is given a specific queue, it will only show jobs pending in that queue.
238 .It Fl r
239 Is an alias for
240 .Nm atrm .
241 .It Fl t
242 For both
243 .Nm
244 and
245 .Nm batch ,
246 the time may be specified in a language-neutral format consisting of:
247 .Bl -tag -width Ds -compact -offset indent
248 .It Ar CC
249 The first two digits of the year (the century).
250 .It Ar YY
251 The second two digits of the year.
252 If
253 .Ar YY
254 is specified, but
255 .Ar CC
256 is not, a value for
257 .Ar YY
258 between 69 and 99 results in a
259 .Ar CC
260 value of 19.
261 Otherwise, a
262 .Ar CC
263 value of 20 is used.
264 .It Ar MM
265 The month of the year, from 01 to 12.
266 .It Ar \&DD
267 The day of the month, from 01 to 31.
268 .It Ar hh
269 The hour of the day, from 00 to 23.
270 .It Ar mm
271 The minute of the hour, from 00 to 59.
272 .It Ar \&SS
273 The second of the minute, from 00 to 61.
274 .El
275 .It Fl V
276 Prints the version number to standard error.
277 .It Fl v
278 For
279 .Nm atq ,
280 shows completed but not yet deleted jobs in the queue.
281 Otherwise shows the time the job will be executed.
282 .El
283 .Sh FILES
284 .Bl -tag -width /var/at/.lockfile -compact
285 .It Pa /var/at/jobs
286 Directory containing job files
287 .It Pa /var/at/spool
288 Directory containing output spool files
289 .It Pa /var/run/utmp
290 Login records
291 .It Pa /var/at/at.allow
292 Allow permission control
293 .It Pa /var/at/at.deny
294 Deny permission control
295 .It Pa /var/at/.lockfile
296 Job-creation lock file.
297 .El
298 .Sh SEE ALSO
299 .Xr nice 1 ,
300 .Xr sh 1 ,
301 .Xr umask 2 ,
302 .Xr atrun 8 ,
303 .Xr cron 8 ,
304 .Xr sendmail 8
305 .Sh STANDARDS
306 The
307 .Nm
308 and
309 .Nm batch
310 utilities conform to
311 .St -p1003.2-92 .
312 .Sh AUTHORS
313 At was mostly written by Thomas Koenig \*[Lt]ig25@rz.uni-karlsruhe.de\*[Gt].
314 The time parsing routines are by David Parsons \*[Lt]orc@pell.chi.il.us\*[Gt].
315 .Sh BUGS
316 If the file
317 .Pa /var/run/utmp
318 is not available or corrupted, or if the user is not logged on at the
319 time
320 .Nm
321 is invoked, the mail is sent to the userid found
322 in the environment variable
323 .Ev LOGNAME .
324 If that is undefined or empty, the current userid is assumed.
325 .Pp
326 .Nm
327 and
328 .Nm batch
329 as presently implemented are not suitable when users are competing for
330 resources.
331 If this is the case for your site, you might want to consider another
332 batch system, such as
333 .Ic nqs .