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
· 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. See
systemd.journal-fields(7) for more information about the collected
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
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, and then waits for the operation to complete. See
journalctl(1) for details.
Request immediate rotation of the journal files. The journalctl--rotate command uses this signal to request journal file
Request that all unwritten log data is written to disk. The
journalctl --sync command uses this signal to trigger journal
synchronization, and then waits for the operation to complete.
A few configuration parameters from journald.conf may be overridden
on the kernel command line:
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.
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/
Configure systemd-journald behavior. See journald.conf(5).
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)
/dev/kmsg, /dev/log, /run/systemd/journal/dev-log,
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.
This page is part of the systemd (systemd system and service manager)
project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a bug
report for this manual page, see
page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2017-03-13. If you dis‐
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systemd 233 SYSTEMD-JOURNALD.SERVICE(8)