{"id":4826,"date":"2026-08-29T18:50:33","date_gmt":"2026-08-29T09:50:33","guid":{"rendered":"https:\/\/donguri3.net\/server-tech\/systemd-timer-setup-2\/"},"modified":"2026-08-29T18:50:34","modified_gmt":"2026-08-29T09:50:34","slug":"systemd-timer-setup","status":"publish","type":"post","link":"https:\/\/donguri3.net\/en\/server-tech\/n8n-automation\/systemd-timer-setup\/","title":{"rendered":"Creating an Automated Script That Runs Every Midnight! ~ Migrating from crontab to systemd Timer ~"},"content":{"rendered":"

This time, we will explain how to migrate from using crontab<\/code> to systemd Timer<\/code>, based on the crontab script we used for updating Let’s Encrypt certificates!<\/p>\n

\n

The Objective<\/h2>\n

We want to run a script every day at midnight (00:00) to renew our SSL certificate!
\nOriginally, it was running with the following crontab<\/code> configuration:<\/p>\n

\n
\n
\n
0 0 * * * bash \/tmp\/letsencrypt.sh<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n
We will change this configuration to systemd Timer<\/code> to enable more flexible and convenient management.<\/p>\n
\n
Procedure: Setting up using a Timer<\/h2>\n
Creating the Service File<\/h3>\n
First, create a “service file” to execute the script. Save the following content with the name \/etc\/systemd\/system\/letsencrypt-renew.service<\/code>.<\/p>\n
\n
\n
\n
[Unit]\nDescription=Run Let's Encrypt renewal script\nWants=letsencrypt-renew.timer\n\n[Service]\nType=oneshot\nExecStart=\/bin\/bash \/tmp\/letsencrypt.sh\n\n[Install]\nWantedBy=multi-user.target<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n
Creating the Timer File<\/h3>\n
Next, create a “timer file” that defines the execution schedule. Write the following content to \/etc\/systemd\/system\/letsencrypt-renew.timer<\/code>.<\/p>\n
\n
\n
\n
[Unit]\nDescription=Run Let's Encrypt renewal script daily at midnight\n\n[Timer]\nOnCalendar=*-*-* 00:00:00\nPersistent=true\n\n[Install]\nWantedBy=timers.target<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n
Here, OnCalendar=*-*-* 00:00:00<\/code> specifies execution at “midnight every day.”<\/p>\n
Applying the Settings and Enabling the Timer<\/h3>\n
Run the following commands in order to apply the configuration.<\/p>\n
\n
\n
\n
sudo systemctl daemon-reload\nsudo systemctl enable letsencrypt-renew.timer\nsudo systemctl start letsencrypt-renew.timer<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n
To verify that the settings have been applied correctly, run the following:<\/p>\n
\n
\n
\n
sudo systemctl list-timers --all<\/code><\/pre>\n<\/div>\n<\/div>\n<\/div>\n
\n
Complete!<\/h2>\n
Now, the Let’s Encrypt certificate renewal script will automatically run every day at midnight! Using systemd Timer<\/code> is very convenient because it makes retrying after failures and checking logs much easier.<\/p>\n","protected":false},"excerpt":{"rendered":"
This time, we will explain how to migrate from using crontab to systemd Timer, based on the crontab script we  […]<\/p>\n","protected":false},"author":4,"featured_media":1071,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_locale":"en_US","_original_post":"https:\/\/donguri3.net\/?p=133","footnotes":""},"categories":[1167],"tags":[97],"class_list":["post-4826","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-n8n-automation","tag-ssl","en-US"],"_links":{"self":[{"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/posts\/4826","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/comments?post=4826"}],"version-history":[{"count":1,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/posts\/4826\/revisions"}],"predecessor-version":[{"id":4829,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/posts\/4826\/revisions\/4829"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/media\/1071"}],"wp:attachment":[{"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/media?parent=4826"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/categories?post=4826"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/tags?post=4826"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}