Cleanup

Check current disk usage:

sudo journalctl --disk-usage

Use rotate function:

sudo journalctl --rotate

Or

Remove all logs and keep the last 2 days:

sudo journalctl --vacuum-time=2days

Or

Remove all logs and only keep the last 100MB:

sudo journalctl --vacuum-size=100M

How to read logs:

Follow specific log for a service:

sudo journalctl -fu SERVICE

Show extended log info and print the last lines of a service:

sudo journalctl -xeu SERVICE