Systemd log files

Systemd only store file in disk if /var/log/journal folder exists.

Restrict log grow

# /etc/systemd/journald.conf
SystemMaxUse=1G
SystemKeepFree=512M
RuntimeMaxUse=512M
RuntimeKeepFree=512M

Reload

systemctl restart  systemd-journald

Clean manually

journalctl --vacuum-size=1G