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Backup with cron
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Overview
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Crontab is a tool that allows you to launch applications on a regular basis,
useful for a server to launch backup scripts, etc.

In this project
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We have set up two commands to make a backup of :

- the postdatabase (dump)
- the imported Excels files (archive and compress)


Useful commands
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Create instruction
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.. code-block:: bash

    crontab -e

Print
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.. code-block:: bash

    crontab -l

In our case the result is

.. code-block:: bash

    # Edit this file to introduce tasks to be run by cron.
    #
    # Each task to run has to be defined through a single line
    # indicating with different fields when the task will be run
    # and what command to run for the task
    #
    # To define the time you can provide concrete values for
    # minute (m), hour (h), day of month (dom), month (mon),
    # and day of week (dow) or use '*' in these fields (for 'any').#
    # Notice that tasks will be started based on the cron's system
    # daemon's notion of time and timezones.
    #
    # Output of the crontab jobs (including errors) is sent through
    # email to the user the crontab file belongs to (unless redirected).
    #
    # For example, you can run a backup of all your user accounts
    # at 5 a.m every week with:
    # 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
    #
    # For more information see the manual pages of crontab(5) and cron(8)
    #
    # m h  dom mon dow   command

    00 21 * * * tar czf /home/EMERGEN-DB/backups/mediafiles/EMERGEN-DB_mediafiles_$(date +\%Y-\%m-\%d).tar.gz -C /home/EMERGEN-DB/mediafiles .
    00 21 * * * sh -c 'docker exec -t emergen-db_db_1 pg_dumpall -c -U postgres > /home/EMERGEN-DB/backups/database/EMERGEN-DB_database_$(date +\%Y-\%m-\%d).sql'


Useful documentation
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Lists of some pages that can help in setting up a cron :

- In french :
    - https://www.linuxtricks.fr/wiki/cron-et-crontab-le-planificateur-de-taches
    - https://doc.ubuntu-fr.org/cron
- In english :
    - https://crontab.guru/
    - https://man7.org/linux/man-pages/man5/crontab.5.html