How to use the journalctl command to read and filter system log messages in Linux

With Linux versions that use systemd, all the system, boot, and kernel log files are collected and managed by a central, logging solution. The format the logs are stored in is binary.  To view this data, use the journalclt command.  To limit the number of entries returned, use the -n switch.

sudo journalctl -n 10

To display new entries as they are created, use the -f switch.

sudo journalctl -f

To view all data, use the -o verbose switch.

sudo journalctl -n 10 -o verbose

To see the log entries related to your last boot, use the -b switch.

journalctl -b

https://www.howtogeek.com/499623/how-to-use-journalctl-to-read-linux-system-logs/