{"id":2147,"date":"2020-12-16T13:38:32","date_gmt":"2020-12-16T11:38:32","guid":{"rendered":"https:\/\/www.virtono.com\/community\/?p=2147"},"modified":"2020-12-10T08:49:48","modified_gmt":"2020-12-10T06:49:48","slug":"cron-run-linux-tools-and-commands-at-boot","status":"publish","type":"post","link":"https:\/\/www.virtono.com\/community\/knowledgebase\/cron-run-linux-tools-and-commands-at-boot\/","title":{"rendered":"Cron: Run Linux tools and commands at boot"},"content":{"rendered":"\n

The Cron task planner with the variable time specification “@reboot” is suitable for scripts and background programs that are to be executed when the system is started.<\/p>\n\n\n\n

There are tasks under Linux that would be basically simple\u00a0solution but is anything but trivial because of the differences between the Linux distributions.\u00a0This includes starting your own programs and scripts when the system boots.\u00a0Actually, this should always be done via the init daemon with a suitable start script.\u00a0If none is available for the desired purpose, you are forced to write one yourself.\u00a0But there is an easier way.<\/p>\n\n\n\n

\"Easy<\/a>
Easy autostart with the Cron task planner.<\/figcaption><\/figure>\n\n\n\n

Debian and Linux distributions derived from it, such as\u00a0Ubuntu\u00a0and\u00a0Raspbian\u00a0, provide the file \u201c\/etc\/rc.local\u201d for their own scripts and programs.\u00a0What is entered there before the final line “exit 0” is carried out by the system with root rights during boot.

The system ignores all errors and skips the rest of the file from the first faulty command so that the information in “rc.local” does not affect the system start.\u00a0If something does not work right away, troubleshooting in the “rc.local” is therefore difficult.\u00a0And for distributions outside the\u00a0Debian\u00a0family tree, the start method is irrelevant anyway, since there is no \u201crc.local\u201d there.

A slightly better, also uncomplicated method of running scripts and programs automatically when booting is provided by the Cron task scheduler.\u00a0This supports the keyword “@reboot” as time specification, which defines the system start as the time.\u00a0Whether a restart or a cold start does not matter.

One advantage is that Cron cannot only execute the entered commands as root.\u00a0Every user of the system can put autostart commands in their own cron table, which are then executed in this user context.

To edit your own cron table, type<\/p>\n\n\n\n

crontab -e<\/code><\/p>\n\n\n\n

in the terminal. With<\/p>\n\n\n\n

sudo crontab -e<\/code><\/p>\n\n\n\n

edit cron entries for the root account. In the called editor you define an autostart call with “@reboot” at the beginning of the line and the exact path to the script or the program file:<\/p>\n\n\n\n

@reboot [Pfad\/zum\/Befehl]<\/code><\/p>\n\n\n\n

As in the rc.local \u201cyou cannot start any graphic applications, not even programs that require a terminal. However, there is a trick with the help of the screen tool to start terminal programs in the background. For example, the line<\/p>\n\n\n\n

@reboot \/usr\/bin\/screen -d -m rtorrent<\/code><\/p>\n\n\n\n

the bit torrent client rtorrent in a screen session, which you can then use<\/p>\n\n\n\n

screen -x<\/code><\/p>\n\n\n\n

can bring them to the foreground at any time.<\/p>\n","protected":false},"excerpt":{"rendered":"

The Cron task planner with the variable time specification “@reboot” is suitable for scripts and background programs that are to be executed when the system is started. There are tasks under Linux that would be basically simple\u00a0solution but is anything but trivial because of the differences between the Linux distributions.\u00a0This<\/p>\n","protected":false},"author":4,"featured_media":2148,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[5,3],"tags":[],"class_list":["post-2147","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-knowledgebase","category-tutorial-how-to"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/www.virtono.com\/community\/wp-content\/uploads\/2020\/12\/cron-jobs.png?fit=800%2C500&ssl=1","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p7ISfL-yD","jetpack_likes_enabled":true,"jetpack-related-posts":[{"id":3392,"url":"https:\/\/www.virtono.com\/community\/knowledgebase\/locations-of-common-log-files-on-linux\/","url_meta":{"origin":2147,"position":0},"title":"Locations of Common Log Files on Linux","author":"George B.","date":"May 25, 2023","format":false,"excerpt":"In this tutorial, we will take you on a journey through the labyrinth of directories and unveil the secret locations of common log files on Linux. 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