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es:howtos:software:at [2019/08/26 17:14 (UTC)] – [at - Task Scheduling] slackwarespanol
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 +<!-- Reviewed 2013-10-16 mfillpot -->
 +<!-- Add your text below. Start with a Headline (see button bar above). -->
 +<note warning>en traduccion</note>
 +====== at - Programación de tareas ======
 +** at ** es una herramienta de programación de tareas que permite que las tareas sean
 +realizado en su sistema. El ** batch ** es como ** at ** pero realiza las tareas únicas cuando la carga del sistema lo permite, todo
 +El comando y las funciones de ** at ** pueden ser replicados por ** batch ** con los mismos argumentos
 +===== Related Commands =====
 +The following commands are included to monitor the **at** command:
 +  * **at** - The program used to submit a one-time task.
 +  * **atq** - The program used to review the queue of jobs submitted with **at**
 +.
 +  * **atrm** - The program used to remove jobs from the at queue.
 +
 +===== at Command Use =====
 +The **at** command can be issued to allow you to write a custom script or
 +point it to a pre-built script. In addition, the broad time specifications
 +allowed increase the complexity.
 +
 +The //-m// argument can be added to any command telling the daemon to mail
 +the user on the local system advising of the completion of the task.
 +
 +==== Scheduling an Existing Script ====
 +This example will tell the **at** application to run the script
 +///home/user/testscript.sh// at 4PM today and e-mail the user upon
 +completion.
 +<code>
 +user@darkstar$ at 16:00 -m -f /home/user/testscript.sh
 +</code>
 +
 +As you can see the //-f// argument means **file** as it points to the
 +file that will be executed.
 +
 +==== Scheduling a New Action ====
 +As seen below, when no file is specified the **at** application opens a
 +prompt for the user to enter the new script.
 +
 +<code>
 +user@darkstar$ at 19:40 -m
 +warning: commands will be executed using /bin/sh
 +at> ping -c 4 www.google.com
 +at> echo $?
 +at> <EOT>
 +job 4 at Sun Dec 30 19:40:00 2012
 +</code>
 +
 +The user will need to type the sequence of commands that will be issued
 +within the prompt, upon completion you close the prompt with the
 +<key>Ctrl</key>+<key>'d'</key>
 + 
 +The command above instructed **at** to ping google 4 times at 7:40PM, return
 +the application status and e-mail the results to the user.
 +
 +<note important>
 +Be sure to note the job number, it is the only visible identifier for the job
 +and must be referenced if you wish to remove the job later.
 +</note>
 +
 +==== Reviewing Queued Tasks ====
 +The command **atq** lists the user's pending jobs. The output is Job Number,
 +date, hour, queue and username.
 +<code>
 +user@darkstar$ atq
 +4 Sun Dec 30 19:40:00 2012 a user
 +</code>
 +
 +Once the task number has been noted you can review the commands that are
 +included in the job by issuing the command //at -c {jobnumber}//, and example is shown below.
 +
 +<code>
 +user@darkstar$ at -c 4
 +#!/bin/sh
 +# atrun uid=1000 gid=1000
 +# mail user 1
 +umask 22
 +....Environment Details....
 +cd /home/user || {
 +   echo 'Execution directory inaccessible' >&2
 +   exit 1
 +}
 +ping -c 4 www.google.com
 +echo $?
 +
 +</code>
 +
 +==== Removing Queued Tasks ====
 +The command **atrm** removes jobs from the pending queue, it does not present
 +any confirmation that the job is removed so it may be advisable to run
 +**atq** after **atrm** to confirm the job has been removed.
 +<code>
 +user@darkstar$ atrm 4
 +</code>
 +
 +====== Further Resources ======
 +  * [[http://unixhelp.ed.ac.uk/CGI/man-cgi?at|at manual page]]
 +  * [[http://www.brunolinux.com/02-The_Terminal/The_at_Command.html|BrunoLinux]]
 +  * [[http://sathyaphoenix.wordpress.com/2009/01/18/using-at-command-to-schedule-jobs-in-linux/]]
 +
 +
 +====== Sources ======
 +
 +<!-- If you copy information from another source, then specify that source -->
 +<!--  * Original source: [[http://www.linux.com/learn/tutorials/261878-intro-to-
 +slackware-package-management|Linux.com]] -->
 +
 +<!-- Authors are allowed to give credit to themselves! -->
 + * Originally written by [[wiki:user:mfillpot | mfillpot]]
 +
 +<!-- Please do not modify anything below, except adding new tags.-->
 +<!-- You must also remove the tag-word "template" below. Otherwise your page wil
 +l not show up in the Table of Contents -->
 +{{tag>howtos task_scheduling author_mfillpot}}
  
 es:howtos:software:at ()