How to manage files in /var/log/journal/ in ubuntu 18.04?

I want to learn about and manage the directory /var/log/journal/ in ubuntu 18.04

• What data is logged to it and when?
• Is there any issue in deleting all files from that directory?
• Is there any way to set delete old data (eg. 1 month)?

I have learned it in weak end - adding a short note here

• journald is - systemd’s logging service

• Journalctl is a utility for querying and displaying logs from journald

• the logs are stored in /var/log/journal/ (except, when we delete the directory)

• we can manage the size and etc in /etc/systemd/journald.conf

• useful journalctl commands

  • journalctl - to view all logs
  • journalctl --disk-usage - to check disk usage
  • journalctl --since "2020-09-24 00:00:00" --until "2020-09-24 23:59:59" - to view logs in between this time range
  • journalctl -f - tail the logs