I have khal (calendar), khard (vcards) and todoman (todo on caldav) installed and use them occasionally. I mostly use my phone and thunderbird to manage contacts and calendars - so they don't find regular use. However, they all are really nice curses/cli tools if you live on the terminal. I don't have any complaints when I do use them. The biggest attraction though is vdirsyncer, a service used to synchronize CalDAV and CardDAV to a directory. Khal and others interface only with this directory and not directly with the server. Vdirsyncer allows you to easily backup and migrate your calendars and contacts between different servers. This is a huge relief if you consider how opaque and locked-in most calendar/contacts services are.

Looks like vdirsyncer can sync with Google calendar and contacts: see

class GoogleContactsStorage(dav.CardDAVStorage):

on https://github.com/pimutils/vdirsyncer/blob/master/vdirsynce...

Dealing with Google's version of IMAP, CalDAV and CardDAV is with the standard that everyone else follows. Every single program (mbsync, offlineimap, vdirsyncer) needs a special section on how to configure for Google alone. It causes a lot of heartache when you try to migrate.

khal is excellent. I've been using it alongside vdirsyncer for a couple of years now. I recommend aliasing 'khal calendar' to cal - a quick look at your day, and upcoming events.

I also highly recommend khard, which manages contacts.

I second these recommendations. I've been using khal and khard (plus `todoman` for to-do list management). They're all nice tools that work well in my CLI-focused workflow. And `vdirsyncer` is a key component, that syncs to my other computers and phone, via a NextCloud instance.