Cleaning old systemd logs:

Cleaning old systemd logs:
* Reduce to latest X bytes: journalctl --vacuum-size=${num}M(egabytes)
* Clean older than X days: journalctl --vacuum-time=${num}d
And setting system logs size limits in /etc/systemd/journald.conf (since they get very big by default, even up to 4GB):
* SystemMaxUse=<number of M/G/...>, eg. SystemMaxUse=1G
Reference:
* systemd - How to clear journalctl - Unix & Linux Stack Exchange: https://unix.stackexchange.com/questions/139513/how-to-clear-journalctl
* How to Clear Systemd Journal Logs in Linux: https://linuxhandbook.com/clear-systemd-journal-logs/
* How to Clear systemd Journal Logs: https://www.baeldung.com/linux/systemd-journal-logs-clear
* Systemd logs (journalctl) are too large and slow: https://askubuntu.com/questions/1012912/systemd-logs-journalctl-are-too-large-and-slow#1012913
* https://www.freedesktop.org/software/systemd/man/latest/journald.conf.html#SystemMaxUse=