1.\" Copyright (c) 1980, 1990 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)at.1 6.4 (Berkeley) 07/24/90 7.\" 8.Dd 9.Dt AT 1 10.Os BSD 4 11.Sh NAME 12.Nm at 13.Nd schedule execution of commands `at' a given time 14.Sh SYNOPSIS 15.Nm at 16.Op Fl c 17.Op Fl s 18.Op Fl m 19.Ar time 20.Op Ar day 21.Op Ar command_file 22.Sh DESCRIPTION 23.Nm At 24schedules execution of commands at the specified 25.Ar time . 26The commands may be given to 27.Nm 28via the 29.Ar command_file 30or accepted from the standard input. 31.Nm At 32will pass these commands to the appropriate 33shell at the requested time. While awaiting 34execution, the jobs reside in a spool directory 35and may be examined by the 36.Xr atq 1 37program. 38.Pp 39Options available: 40.Pp 41.Tp Fl c 42.Ar Command_file 43contains 44.Xr csh 1 45commands. 46.Tp Fl s 47.Ar Command_file 48contains 49.Xr sh 1 50commands. 51.Tp Fl m 52Mail will be sent to the user after the job 53has been run. If errors occur during execution of the job, then 54a copy of the error diagnostics will be sent to the user. If 55no errors occur, then a short message is sent informing the 56user that no errors occurred. 57.Tp 58.Pp 59If a 60.Ar command_file 61is not specified, 62.Nm at 63prompts for commands from standard input until a 64.Ql \&^D 65is typed. 66.Pp 67The format of the spool file is as follows: 68A four line header that includes the owner of the job, the name of the job, 69the shell used to run the job, and whether mail will be 70sent after the job is executed. The header is followed by a 71.Nm cd 72command to the current directory and a 73.Nm umask 74command to set the modes on any files created by the job. 75Then 76.Nm at 77copies all relevant environment variables to the spool file. 78When the script is run, it uses the user and group ID 79of the creator of the spool file. 80.Pp 81The 82.Ar time 83is either a 24 hour military time 84.Em hhmm, 85where 86.Em hh 87is hour and 88.Em mm 89is minutes, or the traditional 12 hour time 90with qualifying options: 91.Df I 92.Dp Li am , a 93am 94.Dp Li pm , p 95pm 96.Dp Li n 97noon 98.Dp Li m 99midnight 100.Dp 101.De 102The time can be abbreviated as shown below in EXAMPLES. 103.Pp 104A 105.Ar day 106of the week may be specified by the first two 107letters of its name. A week (7 days) may be specified by 108the argument 109.Em week . 110If a month name is given, the following argument is expected to 111be the day (numeric). 112.Sh ENVIRONMENT 113If a shell is not specified, 114the current environment variable 115.Ev SHELL 116is used. 117.Sh EXAMPLES 118.Pp 119.Tw Ar 120.Tp Li at 10p 121Execute at 10pm today, or tomorrow 122if 10pm has past. Use the shell 123found in the environment variable 124.Ev SHELL. 125.Tp Li at -c -m 1705 mo 126Execute at 5:05pm on Monday using 127.Xr csh 1 128and send mail upon completion or 129termination of the job. 130.Tp Li at -s -m 1200n week 131Use 132.Xr sh 1 , 133send mail upon completetion, start at noon o'clock, 134one week from today. 135.Tp Li at -s 8a apr 1 136Ideally this would be given late in March. The 137commands would be run at 8 am on April first, using 138the 139.Xr sh 1 . 140.Tp 141.Sh ERRORS 142Errors must be collected via the 143.Fl m 144option or by redirecting the standard output 145from inside the 146.Ar command_file. 147.Sh FILES 148.Dw /var/spool/at/yy.ddd.hhhh.* 149.Di L 150.Dp Pa /var/spool/at 151spooling area 152.Dp Pa /var/spool/at/yy.ddd.hhhh.* 153job file 154.Dp Pa /var/spool/at/past 155directory where jobs are executed from 156.Dp Pa /var/spool/at/lasttimedone 157last time atrun was run 158.Dp Pa /var/libexec/atrun 159executor (run by 160.Xr cron 8 ) 161.Dp 162.Sh SEE ALSO 163.Xr atq 1 , 164.Xr atrm 1 , 165.Xr calendar 1 , 166.Xr cron 8 167.Xr sleep 1 , 168.Sh DIAGNOSTICS 169Complains about various syntax errors and times out of range. 170.Sh HISTORY 171.Nm At 172appeared in Version 7 AT&T UNIX. 173.Sh BUGS 174The queueing mechanism 175.Pa /usr/libexec/atrun , 176is scheduled by 177.Xr cron 8 . 178Frequency with which 179.Xr cron 8 180runs 181.Pa /usr/libexec/atrun 182is site dependent. 183If it is run infrequently, a job may 184fall thru the cracks. 185.Pp 186There are known problems attempting to specify 187a time of 2400 hours to 188.Nm at . 189.Pp 190If the system crashes, mail is not sent to the user informing them that 191the job was not completed. 192.Pp 193Sometimes old spool files are not removed from the directory 194.Pa /var/spool/at/past . 195This is usually due to a system crash, 196and requires that they be removed by hand. 197