Journalctl is a command to view logs collected by systemd.
Tip1. To check the service status, execute below command.
systemctl status systemd-journald.service
Tip2. Main configuration file is
Tip3. To see the logs page by page
Tip4. To see the logs in single page (Do not pipe output into a pager) like cat command
Tip5. To see the logs related to kernel
Tip6. To see the logs related to boot
Tip7. To see the current logs
Tip8. To see the logs since today
journalctl --since today
Tip9. To see the logs between a specified date and time
journalctl --since "2019-03-04 21:22:28" --until "2019-03-04 21:35:02"
Tip10. To see the logs related to systemd service
journalctl -u httpd; journalctl -u mariadb
Tip11. To see the logs according to priority.
"emerg" (0), "alert" (1), "crit" (2), "err" (3),"warning" (4), "notice" (5), "info"(6),"debug" (7) For example. journalctl -p 3 journalctl -p err
Tip12. shows the full-structured entry items with all fields
journalctl -u httpd -o json-pretty
Tip13. formats entries as JSON data structures, but formats them in multiple lines in order to make them more readable by humans.
journalctl -u httpd -o verbose
For Live Installation you may refer below youtube link:-