2022-01-16 18:20:39 +00:00
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---
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title: "cron"
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tags: [ "Documentation", "basics" ]
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---
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2021-05-15 14:41:45 +00:00
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# Cron
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2020-01-02 00:04:35 +00:00
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Various services from cron exist, e.g.
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2021-06-09 00:44:55 +00:00
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> sudo apt -y install cron
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2020-01-02 00:04:35 +00:00
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2021-05-15 14:41:45 +00:00
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Start the cronie with
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2020-01-02 00:04:35 +00:00
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2021-06-09 00:44:55 +00:00
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> sudo systemctl enable --now cron
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2020-01-02 00:04:35 +00:00
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2021-05-15 14:41:45 +00:00
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Specify a cron job with:
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2020-01-02 00:04:35 +00:00
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> cron -e
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You can run a script with:
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*/10 * * * * /home/pi/script.sh
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... which would run every 10 minutes.
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To run something as root, do:
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> sudo crontab -e
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For example, you can update the database, meaning searches with 'locate' command will be faster.
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> */30 * * * * /usr/bin/updatedb
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2021-05-15 14:41:45 +00:00
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## Syntax
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`* * * * *`
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These five points refer to:
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`minute hour day month weekday`
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So '3pm every Sunday' would be:
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`0 15 * * 7`
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Here 'Sunday' is indicated by "7", and '3pm' is 'the 15th hour'.
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The minute is '0' (i.e. '0 minutes past three pm').
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Doing the same thing, but only in February, would be:
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`0 15 * 2 7`
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2020-01-02 00:04:35 +00:00
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# Testing with runparts
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Run-parts runs all executable scripts in a directory.
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> run-parts /etc/cron.hourly
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