systemd-journald


SYNOPSIS
       systemd-journald.service

       systemd-journald.socket

       systemd-journald-dev-log.socket

       systemd-journald-audit.socket

       /lib/systemd/systemd-journald

DESCRIPTION
       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:

       o   Kernel log messages, via kmsg

       o   Simple system log messages, via the libc syslog(3) call

       o   Structured system log messages via the native Journal API, see
           sd_journal_print(4)

       o   Standard output and standard error of system services

       o   Audit records, via the audit subsystem

       The daemon will implicitly collect numerous metadata fields for each
       log messages in a secure and unfakeable way. See systemd.journal-
       fields(7) for more information about the collected metadata.

       Log data collected by the journal is primarily text-based but can also
       include binary data where necessary. All objects stored in the journal
       can be up to 2^64-1 bytes in size.

       By default, the journal stores log data in /run/log/journal/. Since
       /run/ is volatile, log data is lost at reboot. To make the data
       persistent, it is sufficient to create /var/log/journal/ where
       systemd-journald will then store the data:

           mkdir -p /var/log/journal
           systemd-tmpfiles --create --prefix /var/log/journal

       See journald.conf(5) for information about the configuration of this
       service.

SIGNALS
       SIGUSR1
           Request that journal data from /run/ is flushed to /var/ in order
           to make it persistent (if this is enabled). This must be used after
           /var/ is mounted, as otherwise log data from /run is never flushed
           to /var regardless of the configuration. The journalctl --flush
           command uses this signal to request flushing of the journal files,

KERNEL COMMAND LINE
       A few configuration parameters from journald.conf may be overridden on
       the kernel command line:

       systemd.journald.forward_to_syslog=, systemd.journald.forward_to_kmsg=,
       systemd.journald.forward_to_console=, systemd.journald.forward_to_wall=
           Enables/disables forwarding of collected log messages to syslog,
           the kernel log buffer, the system console or wall.

           See journald.conf(5) for information about these settings.

ACCESS CONTROL
       Journal files are, by default, owned and readable by the
       "systemd-journal" system group but are not writable. Adding a user to
       this group thus enables her/him to read the journal files.

       By default, each logged in user will get her/his own set of journal
       files in /var/log/journal/. These files will not be owned by the user,
       however, in order to avoid that the user can write to them directly.
       Instead, file system ACLs are used to ensure the user gets read access
       only.

       Additional users and groups may be granted access to journal files via
       file system access control lists (ACL). Distributions and
       administrators may choose to grant read access to all members of the
       "wheel" and "adm" system groups with a command such as the following:

           # setfacl -Rnm g:wheel:rx,d:g:wheel:rx,g:adm:rx,d:g:adm:rx /var/log/journal/

       Note that this command will update the ACLs both for existing journal
       files and for future journal files created in the /var/log/journal/
       directory.

FILES
       /etc/systemd/journald.conf
           Configure systemd-journald behavior. See journald.conf(5).

       /run/log/journal/machine-id/*.journal,
       /run/log/journal/machine-id/*.journal~,
       /var/log/journal/machine-id/*.journal,
       /var/log/journal/machine-id/*.journal~
           systemd-journald writes entries to files in
           /run/log/journal/machine-id/ or /var/log/journal/machine-id/ with
           the ".journal" suffix. If the daemon is stopped uncleanly, or if
           the files are found to be corrupted, they are renamed using the
           ".journal~" suffix, and systemd-journald starts writing to a new
           file.  /run is used when /var/log/journal is not available, or when
           Storage=volatile is set in the journald.conf(5) configuration file.

       /dev/kmsg, /dev/log, /run/systemd/journal/dev-log,
       /run/systemd/journal/socket, /run/systemd/journal/stdout
           Sockets and other paths that systemd-journald will listen on that
           are visible in the file system. In addition to these, journald can
           listen for audit events using netlink.
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