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at(1) [bsd man page]

AT(1)							      General Commands Manual							     AT(1)

NAME
at - execute commands at a later time SYNOPSIS
at [ -c ] [ -s ] [ -m ] time [ day ] [ file ] DESCRIPTION
At spools away a copy of the named file to be used as input to sh(1) or csh(1). If the -c flag (for (csh(1))) or the -s flag (for (sh(1))) is specified, then that shell will be used to execute the job; if no shell is specified, the current environment shell is used. If no file name is specified, at prompts for commands from standard input until a ^D is typed. If the -m flag is specified, mail will be sent to the user after the job has been run. If errors occur during execution of the job, then a copy of the error diagnostics will be sent to the user. If no errors occur, then a short message is sent informing the user that no errors occurred. The format of the spool file is as follows: A four line header that includes the owner of the job, the name of the job, the shell used to run the job, and whether mail will be set after the job is executed. The header is followed by a cd command to the current directory and a umask command to set the modes on any files created by the job. Then at copies all relevant environment variables to the spool file. When the script is run, it uses the user and group ID of the creator of the spool file. The time is 1 to 4 digits, with an optional following `A', `P', `N' or `M' for AM, PM, noon or midnight. One and two digit numbers are taken to be hours, three and four digits to be hours and minutes. If no letters follow the digits, a 24 hour clock time is understood. The optional day is either (1) a month name followed by a day number, or (2) a day of the week; if the word `week' follows, invocation is moved seven days further off. Names of months and days may be recognizably truncated. Examples of legitimate commands are at 8am jan 24 at -c -m 1530 fr week at -s -m 1200n week At programs are executed by periodic execution of the command /usr/libexec/atrun from cron(8). The granularity of at depends upon the how often atrun is executed. Error output is lost unless redirected or the -m flag is requested, in which case a copy of the errors is sent to the user via mail(1). FILES
/usr/spool/at spooling area /usr/spool/at/yy.ddd.hhhh.* job file /usr/spool/at/past directory where jobs are executed from /usr/spool/at/lasttimedone last time atrun was run /usr/libexec/atrun executor (run by cron(8)) SEE ALSO
atq(1), atrm(1), calendar(1), sleep(1), cron(8) DIAGNOSTICS
Complains about various syntax errors and times out of range. BUGS
Due to the granularity of the execution of /usr/libexec/atrun, there may be bugs in scheduling things almost exactly 24 hours into the future. If the system crashes, mail is not sent to the user informing them that the job was not completed. Sometimes old spool files are not removed from the directory /usr/spool/at/past. This is usually due to a system crash, and requires that they be removed by hand. 4th Berkeley Distribution October 21, 1996 AT(1)

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at(1)							      General Commands Manual							     at(1)

Name
       at, batch - execute commands at a later time

Syntax
       at time [day] [file]
       at -r job...
       at -l [job...]

       batch [file]

Description
       The  and commands use a copy of the named file (standard input default) as input to or at a later time.	A command to the current directory
       is inserted at the beginning, followed by assignments to all environment variables.  When the script is run, it uses the user and group	ID
       of the creator of the copy file.

       The command allows the user to specify when the commands should be executed, while jobs queued with execute when the load level of the sys-
       tem permits.

       The environment variables, current directory, and are retained when the commands are executed.  However, open files,  traps,  and  priority
       are lost.

       Users are permitted to use the and commands if their name appears in the file If that file does not exist, the file is checked to determine
       if the user should be denied access to and If neither file exists, only the superuser is allowed to submit a job.  If only the file  exists
       and is empty, global usage is permitted.  The files consist of one user name per line.

       The  time  is  1  to 4 digits.  It can, but does not have to be, followed by A, P, N or M which stand for AM, PM, noon or midnight, respec-
       tively. The A, P, N, and M suffixes are case-insensitive.  One and two digit numbers are interpreted as hours, three and four digits to	be
       hours  and  minutes. If three digits are specified, the first digit is interpreted to be an hour in the range 0-9, and the second and third
       digits as minutes.  If no letters follow the digits, a 24 hour clock time is presumed.

       In addition to 1-4 digits, and suffixes A, P, M, N, you can also specify:
       at hh:mm
       at h:mm
       at ham
       at hpm
       at noon
       at midnight

       The optional day is either a month name followed by a day number or by a day of the week.  If the word week  follows,  the  or  command	is
       invoked in seven days.  Both commands also recognize standard abbreviations for the days of the week and months of the year.  The following
       are examples of legitimate commands:
       at 8am jan 24

       at 1530 fr week

       The programs are executed by periodic execution of the command from The granularity of depends upon how often atrun is executed.  The  com-
       mand examines the file every minute.  The file determines when is executed.  The default is every 15 minutes on the 1/4 hour. Editing makes
       run more or less frequently.

       Standard output or error output is lost unless it is redirected.

       The and commands write the job number to standard error.

Options
       -r		   Removes jobs previously scheduled by or The number is the number reported at invocation by or  Only	the  superuser	is
			   allowed to remove another user's jobs.

       -l		   Lists all job numbers for all jobs submitted by the user issuing the command.  Even if the user is "root", only numbers
			   for jobs submitted by "root" are displayed.	To see the numbers of all jobs submitted, enter the following command:
			   % ls -l /usr/spool/at

Restrictions
       Due to the granularity of the execution of there may be bugs in scheduling jobs almost exactly 24 hours into the future.

Diagnostics
       Complains about various syntax errors and times that are out of range.

Files
       /usr/lib/atrun	   executor run by cron(8)

       in /usr/spool/at:
	    yy.ddd.hhhh.*  activity for year yy, day dd, hour hhhh.
	    lasttimedone   last hhhh
	    past	   activities in progress
       /usr/spool/at/at.allowlist of allowed users
       /usr/spool/at/at.denylist of denied users
       /usr/spool/at	   spool directory
       /usr/lib/cron	   XOPEN compatibility

See Also
       crontab(5), cron(8)

																	     at(1)

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