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SYSTEMD-JOURNALD.SERVICE(8) | systemd-journald.service | SYSTEMD-JOURNALD.SERVICE(8) |
NAME¶
systemd-journald.service, systemd-journald.socket, systemd-journald-dev-log.socket, systemd-journald-audit.socket, systemd-journald - Journal serviceSYNOPSIS¶
systemd-journald.service systemd-journald.socket systemd-journald-dev-log.socket systemd-journald-audit.socket /lib/systemd/systemd-journaldDESCRIPTION¶
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. 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
SIGNALS¶
SIGUSR1Request 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.
SIGUSR2
Request immediate rotation of the journal files. The
journalctl --rotate command uses this signal to request journal file
rotation.
SIGRTMIN+1
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.
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/
FILES¶
/etc/systemd/journald.confConfigure 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.
SEE ALSO¶
systemd(1), journalctl(1), journald.conf(5), systemd.journal-fields(7), sd-journal(3), systemd-coredump(8), setfacl(1), sd_journal_print(4), pydoc systemd.journalsystemd 230 |