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 6.5 (Berkeley) 03/14/91 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 m 18.Op Fl s 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.Bl -tag -width Ds 41.It Fl c 42.Ar Command_file 43contains 44.Xr csh 1 45commands. 46.It Fl s 47.Ar Command_file 48contains 49.Xr sh 1 50commands. 51.It 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.El 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. 75.Nm At 76copies all relevant environment variables to the spool file. 77When the script is run, it uses the user and group ID 78of the creator of the spool file. 79.Pp 80The 81.Ar time 82is either a 24 hour military time 83.Em hhmm, 84where 85.Em hh 86is hour and 87.Em mm 88is minutes, or the traditional 12 hour time 89with qualifying options: 90.Pp 91.Bl -tag -width "am , a" -offset 12n -compact 92.It Li am , a 93am 94.It Li pm , p 95pm 96.It Li n 97noon 98.It Li m 99midnight 100.El 101.Pp 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.Ar 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.Bl -tag -width Ds 119.It Li at 10p 120Execute at 10pm today, or tomorrow 121if 10pm has past. Use the shell 122found in the environment variable 123.Ev SHELL. 124.It Li at -c -m 1705 mo 125Execute at 5:05pm on Monday using 126.Xr csh 1 127and send mail upon completion or 128termination of the job. 129.It Li at -s -m 1200n week 130Use 131.Xr sh 1 , 132send mail upon completetion, start at noon o'clock, 133one week from today. 134.It Li at -s 8a apr 1 135Ideally this would be given late in March. The 136commands would be run at 8 am on April first, using 137the 138.Xr sh 1 . 139.El 140.Sh ERRORS 141Errors must be collected via the 142.Fl m 143option or by redirecting the standard output 144from inside the 145.Ar command_file. 146.Sh FILES 147.Bl -tag -width /var/spool/at/yy.ddd.hhhh.* -compact 148.It Pa /var/spool/at 149spooling area 150.It Pa /var/spool/at/yy.ddd.hhhh.* 151job file 152.It Pa /var/spool/at/past 153directory where jobs are executed from 154.It Pa /var/spool/at/lasttimedone 155last time atrun was run 156.It Pa /var/libexec/atrun 157executor (run by 158.Xr cron 8 ) 159.El 160.Sh SEE ALSO 161.Xr atq 1 , 162.Xr atrm 1 , 163.Xr calendar 1 , 164.Xr cron 8 165.Xr sleep 1 , 166.Sh DIAGNOSTICS 167Complains about various syntax errors and times out of range. 168.Sh BUGS 169The queueing mechanism 170.Pa /usr/libexec/atrun , 171is scheduled by 172.Xr cron 8 . 173If it is run infrequently, a job may 174fall thru the cracks. 175.Pp 176There are known problems attempting to specify 177a time of 2400 hours to 178.Nm at . 179.Pp 180If the system crashes, mail is not sent to the user informing them that 181the job was not completed. 182.Pp 183Sometimes old spool files are not removed from the directory 184.Pa /var/spool/at/past . 185This is usually due to a system crash, 186and requires that they be removed by hand. 187.Sh HISTORY 188An 189.Nm 190command appeared in Version 7 AT&T UNIX. 191