On Sat, Apr 15, 2023 at 10:45:32PM +0100, Sam Kuper wrote:
  Can't currently bring to mind the utilities for
converting between
 VCard or CSV on the one hand and CardDAV on the other, but I believe
 conversion tools do exist. 
Some potentially useful utilities:
    Virtual Contact File: 
https://wiki.fileformat.com/email/vcf/
    vdirsyncer: 
http://vdirsyncer.pimutils.org/
    vdirsyncer manual:
    
http://readthedocs.org/projects/vdirsyncer/downloads/pdf/latest/
    vdirsyncer configuration examples:
    
https://www.dj-bauer.de/terminal-calendar-with-khal-en.html
    khard: 
https://github.com/scheibler/khard
    Using khard with Mutt: 
https://khard.readthedocs.io/en/v0.14.0/
    calcardbackup: 
https://codeberg.org/BernieO/calcardbackup
    Radicale: 
https://radicale.org/2.1.html
Source:
https://www.linux-magazine.com/Issues/2020/235/Using-CalDAV-CardDAV-to-mana…