NAME

       systemd-journald.service, systemd-journald.socket, systemd-journald - Journal service

SYNOPSIS

       systemd-journald.service

       systemd-journald.socket

       /usr/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
       the kernel, from user processes via the libc syslog(3) call, from STDOUT/STDERR of system
       services or via its native API. It will implicitly collect numerous meta data fields for
       each log messages in a secure and unfakeable way. See systemd.journal-fields(7) for more
       information about the collected meta data.

       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.

       systemd-journald will forward all received log messages to the AF_UNIX SOCK_DGRAM socket
       /run/systemd/journal/syslog (if it exists) which may be used by UNIX syslog daemons to
       process the data further.

       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.

       SIGUSR2
           Request immediate rotation 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=
           Enables/disables forwarding of collected log messages to syslog, the kernel log buffer
           or the system console.

           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
       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.

SEE ALSO

       systemd(1), journalctl(1), journald.conf(5), systemd.journal-fields(7), sd-journal(3),
       setfacl(1)