https://www.youtube.com/watch?v=bnjFscT_FZk

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

/etc/systemd/journald.conf

Tip3. To see the logs page by page

journalctl

Tip4. To see the logs in single page (Do not pipe output into a pager) like cat command

journalctl --no-pager

Tip5. To see the logs related to kernel

journalctl -k

Tip6. To see the logs related to boot

journalctl -b

Tip7. To see the current logs

journalctl -f

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:-

https://www.youtube.com/watch?v=bnjFscT_FZk

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