To install/update on linux use this command and avoid distribution specific packages (to get the latest version) as per https://calibre-ebook.com/download_linux

sudo -v && wget -nv -O- https://raw.githubusercontent.com/kovidgoyal/calibre/master/setup/linux-installer.py | sudo python -c "import sys; main=lambda:sys.stderr.write('Download failed\n'); exec(sys.stdin.read()); main()"

Configuration can be copied from a previous windows installation. Essential files on the linux system are in $HOME/.config/calibre and they are customize.py, global.py, gui.py, tweaks.py and possibly the .json files. Ensure to edit the files and change all path references.

Copied plugin files don't appear to work, but need to be installed separately. This may be due to different versions or due to different install-id in the config file.

Note:

When mounting cifs share and using calibre database on that share, use the 'nobrl' mount option to avoid locking issues and incorrect error messages.

see https://bugs.launchpad.net/calibre/+bug/1760535

Autoupdate script:
https://www.mobileread.com/forums/showthread.php?t=237233
https://github.com/eli-schwartz/calibre-installer

Calibre content server systemd:
https://manual.calibre-ebook.com/server.html

sudo vi /etc/systemd/system/calibre-server.service

/etc/systemd/system/calibre-server.service

[Unit]
Description=calibre content server
After=network.target

[Service]
Type=simple
User=mylinuxuser
Group=mylinuxgroup
ExecStart=/opt/calibre/calibre-server "/path/to/calibre library directory"

[Install]
WantedBy=multi-user.target

sudo systemctl start calibre-server

sudo systemctl status calibre-server

To make it start at boot, run:

sudo systemctl enable calibre-server

Source: https://medium.com/@angeldan1989/a-complete-guide-to-convert-kobo-to-epub-pdf-kindle-d8523197d927

Source: https://medium.com/@angeldan1989/calibre-drm-removal-plugins-2019-remove-ebook-drm-with-calibre-4ec9c07cae80

Download Kobo books to Kobo desktop app/Kobo eReader first.

Downloading Kobo titles onto Kobo eReader or the Kobo desktop will download eBooks in .kepub format (and kepub drm), But downloading Kobo books from Kobo's official site (“My Books”), the file will be .acsm files (in fact they are .epub or .pdf, adobe adept drm adopted).

Note: .acsm files require the use of Adobe Digital Editions (Adobe ID) to deDRM.

Required: obok_plugin v6.5.4 (https://www.epubor.com/download/obok_plugin.zip).

Load the kepub files into calibre.

By default the ebooks are stored in kepub format in …\Kobo\Kobo Desktop Edition\kepub.

Run Calibre, and then add the obok_plugin.zip into Calibre via Preferences → Plugins → Load plugin from file

Restart Calibre; The plugin is available in the top menu bar.

Click on the plugin, it will show all your downloaded KEPUB books. Choose books and select “OK”.

Use Adobe Digital Editions (Adobe ID with the same email address as your kobo account) to download the kobo acsm as ePub/PDF.

Download Calibre DeDRM_plugin.zip (v 6.6.3) http://download.epubor.com/DeDRM_plugin.zip and add it into Calibre.

Restart Calibre, import the kobo acsm books into the library and the DRM will be removed by the plugin automatically.

Adobe Digital Editions stores downloaded ebooks into …\My Documents\My Digital Editions.

If Calibre failed to find the correct Adobe adept key file, configure the via DeDRM plugin → Customize plugin → Adobe Digital Editions ebooks.

The plugin will list all the key files. If you used different Adobe ID to sync your books, there will be different key files.

Make sure to use the same email address as your kobo account to authorize the Adobe ID.