From b750101eb236130cf056c675997decbac904cc49 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 17:35:18 +0200 Subject: Adding upstream version 252.22. Signed-off-by: Daniel Baumann --- man/systemd-journald.service.xml | 357 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 357 insertions(+) create mode 100644 man/systemd-journald.service.xml (limited to 'man/systemd-journald.service.xml') diff --git a/man/systemd-journald.service.xml b/man/systemd-journald.service.xml new file mode 100644 index 0000000..8fa8644 --- /dev/null +++ b/man/systemd-journald.service.xml @@ -0,0 +1,357 @@ + + + + + + + + systemd-journald.service + systemd + + + + systemd-journald.service + 8 + + + + systemd-journald.service + systemd-journald.socket + systemd-journald-dev-log.socket + systemd-journald-audit.socket + systemd-journald@.service + systemd-journald@.socket + systemd-journald-varlink@.socket + systemd-journald + Journal service + + + + systemd-journald.service + systemd-journald.socket + systemd-journald-dev-log.socket + systemd-journald-audit.socket + systemd-journald@.service + systemd-journald@.socket + systemd-journald-varlink@.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 a variety of sources: + + + Kernel log messages, via kmsg + + Simple system log messages, via the libc syslog3 + call + + Structured system log messages via the native Journal API, see + sd_journal_print3 + and Native Journal + Protocol + + Standard output and standard error of service units. For further details see + below. + + Audit records, originating from the kernel audit subsystem + + + The daemon will implicitly collect numerous metadata fields + for each log messages in a secure and unfakeable way. See + systemd.journal-fields7 + 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. Individual fields making up a log record stored in the journal may be up to 2⁶⁴-1 bytes in size. + + The journal service stores log data either persistently below /var/log/journal or in a + volatile way below /run/log/journal/ (in the latter case it is lost at reboot). By default, log + data is stored persistently if /var/log/journal/ exists during boot, with an implicit fallback + to volatile storage otherwise. Use Storage= in + journald.conf5 to configure + where log data is placed, independently of the existence of /var/log/journal/. + + Note that journald will initially use volatile storage, until a call to + journalctl --flush (or sending SIGUSR1 to journald) will cause + it to switch to persistent logging (under the conditions mentioned above). This is done automatically + on boot via systemd-journal-flush.service. + + On systems where /var/log/journal/ does not exist yet but where persistent logging is + desired (and the default journald.conf is used), it is sufficient to create the directory, and + ensure it has the correct access modes and ownership: + + mkdir -p /var/log/journal +systemd-tmpfiles --create --prefix /var/log/journal + + See + journald.conf5 + for information about the configuration of this service. + + + + Stream logging + + The systemd service manager invokes all service processes with standard output and standard error connected + to the journal by default. This behaviour may be altered via the + StandardOutput=/StandardError= unit file settings, see + systemd.exec5 for details. The + journal converts the log byte stream received this way into individual log records, splitting the stream at newline + (\n, ASCII 10) and NUL bytes. + + If systemd-journald.service is stopped, the stream connections associated with all + services are terminated. Further writes to those streams by the service will result in EPIPE + errors. In order to react gracefully in this case it is recommended that programs logging to standard output/error + ignore such errors. If the SIGPIPE UNIX signal handler is not blocked or turned off, such + write attempts will also result in such process signals being generated, see + signal7. + To mitigate this issue, systemd service manager explicitly turns off the SIGPIPE + signal for all invoked processes by default (this may be changed for each unit individually via the + IgnoreSIGPIPE= option, see + systemd.exec5 for + details). After the standard output/standard error streams have been terminated they may not be recovered + until the services they are associated with are restarted. Note that during normal operation, + systemd-journald.service stores copies of the file descriptors for those streams in + the service manager. If systemd-journald.service is restarted using + systemctl restart or equivalent operation instead of a pair of separate + systemctl stop and systemctl start commands (or equivalent + operations), these stream connections are not terminated and survive the restart. It is thus safe to + restart systemd-journald.service, but stopping it is not recommended. + + Note that the log record metadata for records transferred via such standard output/error streams reflect the + metadata of the peer the stream was originally created for. If the stream connection is passed on to other + processes (such as further child processes forked off the main service process), the log records will not reflect + their metadata, but will continue to describe the original process. This is different from the other logging + transports listed above, which are inherently record based and where the metadata is always associated with the + individual record. + + In addition to the implicit standard output/error logging of services, stream logging is also available + via the systemd-cat1 command + line tool. + + Currently, the number of parallel log streams systemd-journald will accept is limited to + 4096. When this limit is reached further log streams may be established but will receive + EPIPE right from the beginning. + + + + Journal Namespaces + + Journal 'namespaces' are both a mechanism for logically isolating the log stream of projects + consisting of one or more services from the rest of the system and a mechanism for improving + performance. Multiple journal namespaces may exist simultaneously, each defining its own, independent log + stream managed by its own instance of systemd-journald. Namespaces are independent of + each other, both in the data store and in the IPC interface. By default only a single 'default' namespace + exists, managed by systemd-journald.service (and its associated socket + units). Additional namespaces are created by starting an instance of the + systemd-journald@.service service template. The instance name is the namespace + identifier, which is a short string used for referencing the journal namespace. Service units may be + assigned to a specific journal namespace through the LogNamespace= unit file setting, + see systemd.exec5 for + details. The switch of + journalctl1 may be + used to view the log stream of a specific namespace. If the switch is not used the log stream of the + default namespace is shown, i.e. log data from other namespaces is not visible. + + Services associated with a specific log namespace may log via syslog, the native logging protocol + of the journal and via stdout/stderr; the logging from all three transports is associated with the + namespace. + + By default only the default namespace will collect kernel and audit log messages. + + The systemd-journald instance of the default namespace is configured through + /etc/systemd/journald.conf (see below), while the other instances are configured + through /etc/systemd/journald@NAMESPACE.conf. The journal + log data for the default namespace is placed in + /var/log/journal/MACHINE_ID (see below) while the data + for the other namespaces is located in + /var/log/journal/MACHINE_ID.NAMESPACE. + + + + 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. Use the + journalctl --flush command to request flushing of the journal files, and wait for + the operation to complete. See + journalctl1 for + details. + + + + SIGUSR2 + + Request immediate rotation of the journal files. Use the journalctl + --rotate command to request journal file rotation, and wait for the operation to + complete. + + + + SIGRTMIN+1 + + Request that all unwritten log data is written to disk. Use the journalctl + --sync command to trigger journal synchronization, and wait 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.conf5 + for information about these settings. + + + + + + Note that these kernel command line options are only honoured by the default namespace, see + above. + + + + 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 them to read + the journal files. + + By default, each user, with a UID outside the range of system users, + dynamic service users, and the nobody user, will get their own set of + journal files in /var/log/journal/. See + Users, Groups, UIDs and GIDs on systemd systems + for more details about UID ranges. These journal + 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.conf5. + + + + + /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 is set in the + journald.conf5 + configuration file. + + When systemd-journald ceases writing to a journal file, + it will be renamed to original-name@suffix.journal + (or original-name@suffix.journal~). + Such files are "archived" and will not be written to any more. + + In general, it is safe to read or copy any journal file (active or archived). + journalctl1 + and the functions in the + sd-journal3 + library should be able to read all entries that have been fully written. + + systemd-journald will automatically remove the oldest + archived journal files to limit disk use. See SystemMaxUse= + and related settings in + journald.conf5. + + + + + /dev/kmsg + /dev/log + /run/systemd/journal/dev-log + /run/systemd/journal/socket + /run/systemd/journal/stdout + + Sockets and other file node paths that systemd-journald will + listen on and are visible in the file system. In addition to these, + systemd-journald can listen for audit events using netlink7. + + + + If journal namespacing is used these paths are slightly altered to include a namespace identifier, see above. + + + + See Also + + systemd1, + journalctl1, + journald.conf5, + systemd.journal-fields7, + sd-journal3, + systemd-coredump8, + setfacl1, + sd_journal_print3, + pydoc systemd.journal + + + + -- cgit v1.2.3