systemd-journald(8)

1SYSTEMD-JOURNALD.SERVICE(8)systemd-journald.serviceSYSTEMD-JOURNALD.SERVICE(8)
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NAME

6       systemd-journald.service, systemd-journald.socket, systemd-journald -
7       Journal service
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SYNOPSIS

10       systemd-journald.service
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12       systemd-journald.socket
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14       /usr/lib/systemd/systemd-journald
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DESCRIPTION

17       systemd-journald is a system service that collects and stores logging
18       data. It creates and maintains structured, indexed journals based on
19       logging information that is received from a variety of sources:
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21       ·   Kernel log messages, via kmsg
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23       ·   Simple system log messages, via the libc syslog(3) call
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25       ·   Structured system log messages via the native Journal API, see
26           sd_journal_print(4)
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28       ·   Standard output and standard error of system services
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30       ·   Audit records, via the audit subsystem
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32       The daemon will implicitly collect numerous metadata fields for each
33       log messages in a secure and unfakeable way. See systemd.journal-
34       fields(7) for more information about the collected metadata.
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36       Log data collected by the journal is primarily text-based but can also
37       include binary data where necessary. All objects stored in the journal
38       can be up to 2^64-1 bytes in size.
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40       By default, the journal stores log data in /run/log/journal/. Since
41       /run/ is volatile, log data is lost at reboot. To make the data
42       persistent, it is sufficient to create /var/log/journal/ where
43       systemd-journald will then store the data.
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45       systemd-journald will forward all received log messages to the
46       AF_UNIX/SOCK_DGRAM socket /run/systemd/journal/syslog, if it exists,
47       which may be used by Unix syslog daemons to process the data further.
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49       See journald.conf(5) for information about the configuration of this
50       service.
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SIGNALS

53       SIGUSR1
54           Request that journal data from /run/ is flushed to /var/ in order
55           to make it persistent (if this is enabled). This must be used after
56           /var/ is mounted, as otherwise log data from /run is never flushed
57           to /var regardless of the configuration.
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59       SIGUSR2
60           Request immediate rotation of the journal files.
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KERNEL COMMAND LINE

63       A few configuration parameters from journald.conf may be overridden on
64       the kernel command line:
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66       systemd.journald.forward_to_syslog=, systemd.journald.forward_to_kmsg=,
67       systemd.journald.forward_to_console=, systemd.journald.forward_to_wall=
68           Enables/disables forwarding of collected log messages to syslog,
69           the kernel log buffer, the system console or wall.
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71           See journald.conf(5) for information about these settings.
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ACCESS CONTROL

74       Journal files are, by default, owned and readable by the
75       "systemd-journal" system group but are not writable. Adding a user to
76       this group thus enables her/him to read the journal files.
77
78       By default, each logged in user will get her/his own set of journal
79       files in /var/log/journal/. These files will not be owned by the user,
80       however, in order to avoid that the user can write to them directly.
81       Instead, file system ACLs are used to ensure the user gets read access
82       only.
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84       Additional users and groups may be granted access to journal files via
85       file system access control lists (ACL). Distributions and
86       administrators may choose to grant read access to all members of the
87       "wheel" and "adm" system groups with a command such as the following:
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89           # setfacl -Rnm g:wheel:rx,d:g:wheel:rx,g:adm:rx,d:g:adm:rx /var/log/journal/
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91       Note that this command will update the ACLs both for existing journal
92       files and for future journal files created in the /var/log/journal/
93       directory.
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FILES

96       /etc/systemd/journald.conf
97           Configure systemd-journald behaviour. See journald.conf(5).
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99       /run/log/journal/machine-id/*.journal,
100       /run/log/journal/machine-id/*.journal~,
101       /var/log/journal/machine-id/*.journal,
102       /var/log/journal/machine-id/*.journal~
103           systemd-journald writes entries to files in
104           /run/log/journal/machine-id/ or /var/log/journal/machine-id/ with
105           the ".journal" suffix. If the daemon is stopped uncleanly, or if
106           the files are found to be corrupted, they are renamed using the
107           ".journal~" suffix, and systemd-journald starts writing to a new
108           file.  /run is used when /var/log/journal is not available, or when
109           Storage=volatile is set in the journald.conf(5) configuration file.
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