1.Dd August 11, 2018 2.Dt "AT" 1 3.Os 4.Sh NAME 5.Nm at , 6.Nm batch , 7.Nm atq , 8.Nm atrm 9.Nd queue, examine or delete jobs for later execution 10.Sh SYNOPSIS 11.Nm at 12.Op Fl q Ar queue 13.Op Fl f Ar file 14.Op Fl mldbv 15.Ar time 16.Nm at 17.Op Fl q Ar queue 18.Op Fl f Ar file 19.Op Fl mldbv 20.Fl t 21.Sm off 22.Op Oo Ar CC Oc Ar YY 23.Ar MM DD hh mm Op . Ar SS 24.Sm on 25.Nm at 26.Fl c Ar job Op Ar job ... 27.Nm at 28.Fl l Op Ar job ... 29.Nm at 30.Fl l 31.Fl q Ar queue 32.Nm at 33.Fl r Ar job Op Ar job ... 34.Pp 35.Nm atq 36.Op Fl q Ar queue 37.Op Fl v 38.Pp 39.Nm atrm 40.Ar job 41.Op Ar job ... 42.Pp 43.Nm batch 44.Op Fl q Ar queue 45.Op Fl f Ar file 46.Op Fl mv 47.Op Ar time 48.Sh DESCRIPTION 49The 50.Nm at 51and 52.Nm batch 53utilities 54read commands from standard input or a specified file which are to 55be executed at a later time, using 56.Xr sh 1 . 57.Bl -tag -width indent 58.It Nm at 59executes commands at a specified time; 60.It Nm atq 61lists the user's pending jobs, unless the user is the superuser; in that 62case, everybody's jobs are listed; 63.It Nm atrm 64deletes jobs; 65.It Nm batch 66executes commands when system load levels permit; in other words, when 67the load average drops below _LOADAVG_MX times number of active CPUs, 68or the value specified in the invocation of 69.Nm atrun . 70.El 71.Pp 72The 73.Nm at 74utility allows some moderately complex 75.Ar time 76specifications. 77It accepts times of the form 78.Ar HHMM 79or 80.Ar HH:MM 81to run a job at a specific time of day. 82(If that time is already past, the next day is assumed.) 83As an alternative, the following keywords may be specified: 84.Cm midnight , 85.Cm noon , 86or 87.Cm teatime 88(4pm) 89and time-of-day may be suffixed with 90.Cm AM 91or 92.Cm PM 93for running in the morning or the evening. 94The day on which the job is to be run may also be specified 95by giving a date in the form 96.Ar \%month-name day 97with an optional 98.Ar year , 99or giving a date of the forms 100.Ar DD.MM.YYYY , 101.Ar DD.MM.YY , 102.Ar MM/DD/YYYY , 103.Ar MM/DD/YY , 104.Ar MMDDYYYY , 105or 106.Ar MMDDYY . 107The specification of a date must follow the specification of 108the time of day. 109Time can also be specified as: 110.Op Cm now 111.Cm \&+ Ar count \%time-units , 112where the time-units can be 113.Cm minutes , 114.Cm hours , 115.Cm days , 116.Cm weeks , 117.Cm months 118or 119.Cm years 120and 121.Nm 122may be told to run the job today by suffixing the time with 123.Cm today 124and to run the job tomorrow by suffixing the time with 125.Cm tomorrow . 126.Pp 127For example, to run a job at 4pm three days from now, use 128.Ql at 4pm + 3 days , 129to run a job at 10:00am on July 31, use 130.Ql at 10am Jul 31 131and to run a job at 1am tomorrow, use 132.Ql at 1am tomorrow . 133.Pp 134The 135.Nm at 136utility also supports the 137.Tn POSIX 138time format (see 139.Fl t 140option). 141.Pp 142For both 143.Nm 144and 145.Nm batch , 146commands are read from standard input or the file specified 147with the 148.Fl f 149option and executed. 150The working directory, the environment (except for the variables 151.Ev TERM , 152.Ev TERMCAP , 153.Ev DISPLAY 154and 155.Ev _ ) 156and the 157.Ar umask 158are retained from the time of invocation. 159An 160.Nm 161or 162.Nm batch 163command invoked from a 164.Xr su 1 165shell will retain the current userid. 166The user will be mailed standard error and standard output from his 167commands, if any. 168Mail will be sent using the command 169.Xr sendmail 8 . 170If 171.Nm 172is executed from a 173.Xr su 1 174shell, the owner of the login shell will receive the mail. 175.Pp 176The superuser may use these commands in any case. 177For other users, permission to use 178.Nm 179is determined by the files 180.Pa _PERM_PATH/at.allow 181and 182.Pa _PERM_PATH/at.deny . 183.Pp 184If the file 185.Pa _PERM_PATH/at.allow 186exists, only usernames mentioned in it are allowed to use 187.Nm . 188In these two files, a user is considered to be listed only if the user 189name has no blank or other characters before it on its line and a 190newline character immediately after the name, even at the end of 191the file. 192Other lines are ignored and may be used for comments. 193.Pp 194If 195.Pa _PERM_PATH/at.allow 196does not exist, 197.Pa _PERM_PATH/at.deny 198is checked, every username not mentioned in it is then allowed 199to use 200.Nm . 201.Pp 202If neither exists, only the superuser is allowed use of 203.Nm . 204This is the default configuration. 205.Sh IMPLEMENTATION NOTES 206Note that 207.Nm 208is implemented through the 209.Xr cron 8 210daemon by calling 211.Xr atrun 8 212every five minutes. 213This implies that the granularity of 214.Nm 215might not be optimal for every deployment. 216If a finer granularity is desired, the 217.Pa /etc/cron.d/at 218file can be edited and will be read by the system crontab, from which 219the 220.Ev SHELL 221and 222.Ev PATH 223environment variables are inherited. 224.Sh OPTIONS 225.Bl -tag -width indent 226.It Fl q Ar queue 227Use the specified queue. 228A queue designation consists of a single letter; valid queue designations 229range from 230.Ar a 231to 232.Ar z 233and 234.Ar A 235to 236.Ar Z . 237The 238.Ar _DEFAULT_AT_QUEUE 239queue is the default for 240.Nm 241and the 242.Ar _DEFAULT_BATCH_QUEUE 243queue for 244.Nm batch . 245Queues with higher letters run with increased niceness. 246If a job is submitted to a queue designated with an uppercase letter, it 247is treated as if it had been submitted to batch at that time. 248If 249.Nm atq 250is given a specific queue, it will only show jobs pending in that queue. 251.It Fl m 252Send mail to the user when the job has completed even if there was no 253output. 254.It Fl f Ar file 255Read the job from 256.Ar file 257rather than standard input. 258.It Fl l 259With no arguments, list all jobs for the invoking user. 260If one or more 261job numbers are given, list only those jobs. 262.It Fl d 263Is an alias for 264.Nm atrm 265(this option is deprecated; use 266.Fl r 267instead). 268.It Fl b 269Is an alias for 270.Nm batch . 271.It Fl v 272For 273.Nm atq , 274shows completed but not yet deleted jobs in the queue; otherwise 275shows the time the job will be executed. 276.It Fl c 277Cat the jobs listed on the command line to standard output. 278.It Fl r 279Remove the specified jobs. 280.It Fl t 281Specify the job time using the \*[Px] time format. 282The argument should be in the form 283.Sm off 284.Op Oo Ar CC Oc Ar YY 285.Ar MM DD hh mm Op . Ar SS 286.Sm on 287where each pair of letters represents the following: 288.Pp 289.Bl -tag -width indent -compact -offset indent 290.It Ar CC 291The first two digits of the year (the century). 292.It Ar YY 293The second two digits of the year. 294.It Ar MM 295The month of the year, from 1 to 12. 296.It Ar DD 297the day of the month, from 1 to 31. 298.It Ar hh 299The hour of the day, from 0 to 23. 300.It Ar mm 301The minute of the hour, from 0 to 59. 302.It Ar SS 303The second of the minute, from 0 to 60. 304.El 305.Pp 306If the 307.Ar CC 308and 309.Ar YY 310letter pairs are not specified, the values default to the current 311year. 312If the 313.Ar SS 314letter pair is not specified, the value defaults to 0. 315.El 316.Sh FILES 317.Bl -tag -width _ATJOB_DIR/_LOCKFILE -compact 318.It Pa _ATJOB_DIR 319directory containing job files 320.It Pa _ATSPOOL_DIR 321directory containing output spool files 322.It Pa /var/run/utx.active 323login records 324.It Pa _PERM_PATH/at.allow 325allow permission control 326.It Pa _PERM_PATH/at.deny 327deny permission control 328.It Pa _ATJOB_DIR/_LOCKFILE 329job-creation lock file 330.El 331.Sh SEE ALSO 332.Xr nice 1 , 333.Xr sh 1 , 334.Xr umask 2 , 335.Xr atrun 8 , 336.Xr cron 8 , 337.Xr sendmail 8 338.Sh AUTHORS 339.An -nosplit 340At was mostly written by 341.An Thomas Koenig Aq Mt ig25@rz.uni-karlsruhe.de . 342The time parsing routines are by 343.An David Parsons Aq Mt orc@pell.chi.il.us , 344with minor enhancements by 345.An Joe Halpin Aq Mt joe.halpin@attbi.com . 346.Sh BUGS 347If the file 348.Pa /var/run/utx.active 349is not available or corrupted, or if the user is not logged on at the 350time 351.Nm 352is invoked, the mail is sent to the userid found 353in the environment variable 354.Ev LOGNAME . 355If that is undefined or empty, the current userid is assumed. 356.Pp 357The 358.Nm at 359and 360.Nm batch 361utilities 362as presently implemented are not suitable when users are competing for 363resources. 364If this is the case, another batch system such as 365.Em nqs 366may be more suitable. 367.Pp 368Specifying a date past 2038 may not work on some systems. 369