20210528 - a Slackware upgrade causes the page rendering to fail. Apologies and I am looking for the cause.
Reported as https://forum.dokuwiki.org/d/19270-dokuwiki-instance-no-longer-rendering-some-syntax-correctly

Welcome to the Slackware Documentation Project

Planification de Tâches dans Linux

TRADUCTION en cours – //Cedric M. 2015/09/11 01:52</note> =====Introduction===== Cet article traite de certains outils utilisés dans un système Linux pour planifier des tâches à exécuter automatiquement à des intervalles de temps spécifiques ou à un moment donné. Cet article ne détaillera pas les commandes en profondeur; il est juste une brève introduction à l'utilisation de ces commandes. Lisez les HOWTOS individuels de chaques commandes pour plus de précisions sur leurs options. Quelques daemons Linux/UNIX de planification de tâches : <note>NdT: Les liens suivants font référence aux versions originales.</note> * at – planification de tâches unique * cron – le planificateur périodique le plus utilisé * anacron – anachronistic cron; a periodic scheduler that doesn't rely on the system being left on 24×7 ===== Utiliser at===== La commande at permet à un utilisateur d'exécuter des commandes ou des scripts à une date (obligatoire) et heure (facultatif) spécifiques. La commande peut être passé sur l'entrée standard, en redirection ou dans un fichier. <code> darkstar:~% at </code> ===== at en mode Interractif ===== Utiliser la commande at avec l'entrée standard (avec le clavier) est un petit peu plus compliqué que de taper une ligne de commande au prompt. La commande utilise un “sub-shell” pour rassembler les information demandées. Une fois que l'entrée de la commande d'information est complète, Ctrl+D (EOT) signifiera la fin de l'entrée. L'argument -m spécifie qu'un message mèl sera envoyé à l'utilisateur lorsque le job sera terminé, à moins qu'une sortie ait été créée. <code> darkstar:~% at 12:01 -m warning: commands will be executed using (in order) a) $SHELL b) login shell c) /bin/sh at> ./my_script.sh at> <EOT> job 4 at 2015-06-22 12:01 darkstar:~% </code> =====File-driven at===== Commands can also be contained within a file and run by at: <code> darkstar:~% at 12:32 -m -f /usr/local/bin/my_script.sh warning: commands will be executed using (in order) a) $SHELL b) login shell c) /bin/sh job 8 at 2015-06-22 12:10 </code> The -m flag will email the user after completion of the command; the -f flag specifies the command will read the job from a file, not from standard input. After the command is typed in (and the appropriate warning is displayed), the at job number1) is displayed. =====at Internal Scheduling===== The job numbers provided after a command is typed in, or when a file is read, allow the user to know which internal job will be run in sequential order. If a user wants to delete a specific task, all that needs to be known is this internal job number. To remove the job, the command atrm (at remove) is used: <code> darkstar:~% at -l 7 2015-06-22 12:10 p tux 8 2015-06-22 12:15 p root </code> The command atq (at queue) is the same as at -l: <code> darkstar:~% atq 7 2015-06-22 12:10 p tux 8 2015-06-22 12:15 p root </code> To remove the user job, use atrm with the job number: <code> darkstar:~% atrm 7 </code> =====Using cron===== cron is a daemon that runs tasks in the background at specific times. For example, if you want to automate downloads of patches on a specific day (Monday), date (2 July), or time (1300), cron will allow you to set this up in a variety of ways. The flexibility inherent in cron can allow administrators and power users to automate repetitive tasks, such as creating backups and system maintenance. cron is usually configured using a crontab file. The following command will open your user account crontab file: <code> darkstar:~% crontab -e </code> To edit the system-level crontab, first log into the root account: <code> darkstar:~# crontab -e </code> If your system has sudo installed, type in: <code> darkstar:~% sudo crontab -e </code> The crontab file syntax is: <code> # * * * * * command to execute # │ │ │ │ │ # │ │ │ │ │ # │ │ │ │ └───── day of week (0 - 6) (Sun(0) /Mon (1)/Tue (2)/Wed (3)/Thu (4)/Fri (5)/Sat (6)) # │ │ │ └────────── month (1 - 12) # │ │ └─────────────── day of month (1 - 31) # │ └──────────────────── hour (0 - 23) # └───────────────────────── min (0 - 59) </code> Using an asterisk in any placeholder location, will match any value. For example, the following will run example_script.sh at noon (1200) everyday during the first three months of the year: <code> #For more information see the manual pages of crontab(5) and cron(8) # # min hr day month weekday command # # 0 11 * 1-3 * /home/user/example_script.sh </code> =====Using anacron===== <note> anacron is not installed in Slackware by default.2)
1)
As distinct from a process ID (PID) known to the operating system
2)
See [[http://slackbuilds.org/repository/13.37/system/anacron/|Slackbuilds.org]] for more information on **anacron on Slackware)) </note> anacron is unique from cron in the respect that it does not expect the operating system to be running continuously like a 24×7 server. If the time of execution passes while the system is turned off, anacron executes the command automatically when the machine is turned back on. The reverse is not true for cron - if the computer is turned off during the time of scheduled execution, cron will not execute the job. Another key difference between anacron and cron is the minimum chronological “granularity” - anacron can only execute jobs by day, versus the ability of cron to execute by the minute. Finally, anacron can only be used by root, while cron** can be used by root and normal users. ====== Sources ======