systemd Developer Lennart Poettering lennart@poettering.net journalctl 1 journalctl Query the systemd journal journalctl OPTIONS MATCHES journalctl may be used to query the contents of the systemd1 journal as written by systemd-journald.service8. If called without parameter will show the full contents of the journal, starting with the oldest entry collected. If one or more match arguments are passed the output is filtered accordingly. A match is in the format FIELD=VALUE, e.g. _SYSTEMD_UNIT=httpd.service, referring to the components of a structured journal entry. See systemd.journal-fields7 for a list of well-known fields. If multiple matches are specified matching different fields the log entries are filtered by both, i.e. the resulting output will show only entries matching all the specified matches of this kind. If two matches apply to the same field, then they are automatically matched as alternatives, i.e. the resulting output will show entries matching any of the specified matches for the same field. Finally, if the character "+" appears as separate word on the command line all matches before and after are combined in a disjunction (i.e. logical OR). As shortcuts for a few types of field/value matches file paths may be specified. If a file path refers to an executable file, this is equivalent to an _EXE= match for the canonicalized binary path. Similar, if a path refers to a device node, this is equivalent to a _KERNEL_DEVICE= match for the device. Output is interleaved from all accessible journal files, whether they are rotated or currently being written, and regardless whether they belong to the system itself or are accessible user journals. All users are granted access to their private per-user journals. However, by default only root and users who are members of the adm group get access to the system journal and the journals of other users. The following options are understood: --help -h Prints a short help text and exits. --version Prints a short version string and exits. --no-pager Do not pipe output into a pager. --all -a Show all fields in full, even if they include unprintable characters or are very long. --follow -f Show only most recent journal entries, and continuously print new entries as they are appended to the journal. --lines= -n Controls the number of journal lines to show, counting from the most recent ones. Takes a positive integer argument. In follow mode defaults to 10, otherwise is unset thus not limiting how many lines are shown. --no-tail Show all stored output lines, even in follow mode. Undoes the effect of --lines=. --output= -o Controls the formatting of the journal entries that are shown. Takes one of short, short-monotonic, verbose, export, json, json-pretty, cat. short is the default and generates an output that is mostly identical to the formatting of classic syslog log files, showing one line per journal entry. short-monotonic is very similar but shows monotonic timestamps instead of wallclock timestamps. verbose shows the full structured entry items with all fields. export serializes the journal into a binary (but mostly text-based) stream suitable for backups and network transfer (see Journal Export Format for more information). json formats entries as JSON data structures, one per line. json-pretty also formats entries as JSON data structures, but formats them in multiple lines in order to make them more readable for humans. cat generates a very terse output only showing the actual message of each journal entry with no meta data, not even a timestamp. --quiet -q Suppresses any warning message regarding inaccessible system journals when run as normal user. --merge -m Show entries interleaved from all available journals, including remote ones. --this-boot -b Show data only from current boot. --directory= -D Takes an absolute directory path as argument. If specified will operate on the specified journal directory instead of the default runtime and system journal paths. -p --priority= Filter output by message priorities or priority ranges. Takes either a single numeric or textual log level (i.e. between 0/emerg and 7/debug), or a range of numeric/text log levels in the form FROM..TO. The log levels are the usual syslog log levels as documented in syslog3, i.e. emerg (0), alert (1), crit (2), err (3), warning (4), notice (5), info (6), debug (7). If a single log level is specified all messages with this log levels or a lower (hence more important) log level are shown. If a range is specified all messages within the range are shown, including both the start and the end value of the range. --new-id128 Instead of showing journal contents generate a new 128 bit ID suitable for identifying messages. This is intended for usage by developers who need a new identifier for a new message they introduce and want to make recognizable. Will print the new ID in three different formats which can be copied into source code or similar. --header Instead of showing journal contents show internal header information of the journal fiels accessed. --disk-usage Shows the current disk usage of all journal files. --setup-keys Instead of showing journal contents generate a new key pair for Forward Secure Sealing (FSS). This will generate a sealing key and a verification key. The sealing key is stored in the journal data directory and shall remain on the host. The verification key should be stored externally. --interval= Specifies the change interval for the sealing key, when generating an FSS key pair with --setup-keys. Shorter intervals increase CPU consumption but shorten the time range of undetectable journal alterations. Defaults to 15min. --verify Check the journal file for internal consistency. If the file has been generated with FSS enabled, and the FSS verification key has been specified with --verify-key= authenticity of the journal file is verified. --verify-key= Specifies the FSS verification key to use for the --verify operation. On success 0 is returned, a non-zero failure code otherwise. $SYSTEMD_PAGER Pager to use when --no-pager is not given; overrides $PAGER. Setting this to an empty string or the value cat is equivalent to passing --no-pager. Without arguments all collected logs are shown unfiltered: journalctl With one match specified all entries with a field matching the expression are shown: journalctl _SYSTEMD_UNIT=avahi-daemon.service If two different fields are matched only entries matching both expressions at the same time are shown: journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097 If two matches refer to the same field all entries matching either expression are shown: journalctl _SYSTEMD_UNIT=avahi-daemon.service _SYSTEMD_UNIT=dbus.service If the separator "+" is used two expression may be combined in a logical OR. The following will show all messages from the Avahi service process with the PID 28097 plus all messages from the D-Bus service (from any of its processes): journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097 + _SYSTEMD_UNIT=dbus.service Show all logs generated by the D-Bus executable: journalctl /usr/bin/dbus-daemon Show all logs of the kernel device node /dev/sda: journalctl /dev/sda systemd1, systemd-journald.service8, systemctl1, systemd.journal-fields7, journald.conf5