systemd-journald is a system service that collects and stores logging data from various sources, such

as kernel, user-mode programs, and services1. It creates and maintains structured, indexed journals

that include metadata and binary data where necessary1. The journal format is secure and

unfakeable1. systemd-journald is not incompatible with syslog and can coexist with it. It can forward

log messages to a syslog daemon for further processing, filtering, or storage2. This can be enabled by

setting the ForwardToSyslog option to yes in the /etc/systemd/journald.conf file2. systemd-journald

does not only process messages of systemd, but also messages of any other tools that use the

standard logging interfaces, such as syslog(3), sd_journal_print(3), or systemd-cat(1)1. systemd-

journald also supports syslog facilities, such as kern, user, and auth, which are used to specify the

type of program that is logging the message3. These facilities can be used to filter the journal entries

by using the -p or --priority option of the journalctl command4. For example, to show only kernel

messages, we can use journalctl -p kern4. Reference:

systemd-journald.service

Introduction to the Systemd journal

systemd/Journal

journalctl: Query the systemd Journal