The journalctl tool queries the contents of the systemd journal.
The following command displays the messages that systemd generated the last time the machine started:
journalctl -b
The following command reveals the messages for the systemd service unit specified by the -u option:
journalctl -u auditd
In the above example, auditd is the system service unit.
For more information, see the journalctl man page by running the following command on Photon OS:
man journalctl