Questions tagged [systemd-journald]

systemd-journald is the journalling service in systems with systemd as init. From the manpage:

systemd-journald is a system service that collects and stores logging
data. It creates and maintains structured, indexed journals based on
logging information that is received from a variety of sources:
·   Kernel log messages, via kmsg
·   Simple system log messages, via the libc syslog(3) call
·   Structured system log messages via the native Journal API, see
    sd_journal_print(4)
·   Standard output and standard error of system services
·   Audit records, via the audit subsystem
The daemon will implicitly collect numerous metadata fields for each
log messages in a secure and unfakeable way.

journald logs are typically accessed by the journalctl command, which has a powerful set of options for filtering log entries of interest. By default journalctl without any options will show the whole log.

• journalctl /usr/bin/sshd - logs from the /usr/bin/sshd command
• journalctl -u sshd - logs from the sshd service (or unit)
• journalctl -b1 - logs from during the previous boot
• journalctl _PID=123 - logs from processes with PID 123
• journalctl -p3 - filters output messages from log level alert, critical and error
• and many other options.