10 .Nd queue, examine or delete jobs for later execution
24 .Ar MM DD hh mm Op . Ar SS
27 .Fl c Ar job Op Ar job ...
34 .Fl r Ar job Op Ar job ...
55 read commands from standard input or a specified file which are to
56 be executed at a later time, using
58 .Bl -tag -width indent
60 executes commands at a specified time;
62 lists the user's pending jobs, unless the user is the superuser; in that
63 case, everybody's jobs are listed;
67 executes commands when system load levels permit; in other words, when
68 the load average drops below _LOADAVG_MX times number of active CPUs,
69 or the value specified in the invocation of
75 utility allows some moderately complex
78 It accepts times of the form
82 to run a job at a specific time of day.
83 (If that time is already past, the next day is assumed.)
84 As an alternative, the following keywords may be specified:
90 and time-of-day may be suffixed with
94 for running in the morning or the evening.
95 The day on which the job is to be run may also be specified
96 by giving a date in the form
100 or giving a date of the forms
107 The specification of a date must follow the specification of
109 Time can also be specified as:
111 .Em + Ar count \%time-units ,
112 where the time-units can be
122 may be told to run the job today by suffixing the time with
124 and to run the job tomorrow by suffixing the time with
127 For example, to run a job at 4pm three days from now, use
128 .Nm at Ar 4pm + 3 days ,
129 to run a job at 10:00am on July 31, use
130 .Nm at Ar 10am Jul 31
131 and to run a job at 1am tomorrow, use
132 .Nm at Ar 1am tomorrow .
136 utility also supports the
146 commands are read from standard input or the file specified
150 The working directory, the environment (except for the variables
158 are retained from the time of invocation.
163 command invoked from a
165 shell will retain the current userid.
166 The user will be mailed standard error and standard output from his
168 Mail will be sent using the command
174 shell, the owner of the login shell will receive the mail.
176 The superuser may use these commands in any case.
177 For other users, permission to use
179 is determined by the files
180 .Pa _PERM_PATH/at.allow
182 .Pa _PERM_PATH/at.deny .
185 .Pa _PERM_PATH/at.allow
186 exists, only usernames mentioned in it are allowed to use
188 In these two files, a user is considered to be listed only if the user
189 name has no blank or other characters before it on its line and a
190 newline character immediately after the name, even at the end of
192 Other lines are ignored and may be used for comments.
195 .Pa _PERM_PATH/at.allow
197 .Pa _PERM_PATH/at.deny
198 is checked, every username not mentioned in it is then allowed
202 If neither exists, only the superuser is allowed use of
204 This is the default configuration.
205 .Sh IMPLEMENTATION NOTES
208 is implemented through the
213 This implies that the granularity of
215 might not be optimal for every deployment.
216 If a finer granularity is desired, the
218 file can be edited and will be read by the system crontab, from which
223 environment variables are inherited.
225 .Bl -tag -width indent
227 Use the specified queue.
228 A queue designation consists of a single letter; valid queue designations
238 .Ar _DEFAULT_AT_QUEUE
239 queue is the default for
242 .Ar _DEFAULT_BATCH_QUEUE
245 Queues with higher letters run with increased niceness.
246 If a job is submitted to a queue designated with an uppercase letter, it
247 is treated as if it had been submitted to batch at that time.
250 is given a specific queue, it will only show jobs pending in that queue.
252 Send mail to the user when the job has completed even if there was no
257 rather than standard input.
259 With no arguments, list all jobs for the invoking user.
261 job numbers are given, list only those jobs.
265 (this option is deprecated; use
274 shows completed but not yet deleted jobs in the queue; otherwise
275 shows the time the job will be executed.
277 Cat the jobs listed on the command line to standard output.
279 Remove the specified jobs.
281 Specify the job time using the \*[Px] time format.
282 The argument should be in the form
284 .Op Oo Ar CC Oc Ar YY
285 .Ar MM DD hh mm Op . Ar SS
287 where each pair of letters represents the following:
289 .Bl -tag -width indent -compact -offset indent
291 The first two digits of the year (the century).
293 The second two digits of the year.
295 The month of the year, from 1 to 12.
297 the day of the month, from 1 to 31.
299 The hour of the day, from 0 to 23.
301 The minute of the hour, from 0 to 59.
303 The second of the minute, from 0 to 60.
310 letter pairs are not specified, the values default to the current
314 letter pair is not specified, the value defaults to 0.
317 .Bl -tag -width _ATJOB_DIR/_LOCKFILE -compact
319 directory containing job files
321 directory containing output spool files
322 .It Pa /var/run/utx.active
324 .It Pa _PERM_PATH/at.allow
325 allow permission control
326 .It Pa _PERM_PATH/at.deny
327 deny permission control
328 .It Pa _ATJOB_DIR/_LOCKFILE
329 job-creation lock file
340 At was mostly written by
341 .An Thomas Koenig Aq Mt ig25@rz.uni-karlsruhe.de .
342 The time parsing routines are by
343 .An David Parsons Aq Mt orc@pell.chi.il.us ,
344 with minor enhancements by
345 .An Joe Halpin Aq Mt joe.halpin@attbi.com .
348 .Pa /var/run/utx.active
349 is not available or corrupted, or if the user is not logged on at the
352 is invoked, the mail is sent to the userid found
353 in the environment variable
355 If that is undefined or empty, the current userid is assumed.
362 as presently implemented are not suitable when users are competing for
364 If this is the case, another batch system such as
366 may be more suitable.
368 Specifying a date past 2038 may not work on some systems.