journalctl

systemd
Developer Lennart Poettering lennart@poettering.net
journalctl 1
journalctl Query the systemd journal
`journalctl OPTIONS MATCHES`

## Description

`journalctl` may be used to query the contents of the systemd 1 journal as written by systemd-journald.service 8.

If called without parameter it 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-fields 7 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.

## Options

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 the 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. The argument is optional, and if specified is a positive integer. If not specified and in follow mode defaults to 10. If this option is not passed and follow mode is not enabled, how many lines are shown is not limited.

`--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`, `json-sse`, `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. `json-sse` also formats entries as JSON data structures, but wraps them in a format suitable for Server-Sent Events. `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. This will add a match for `_BOOT_ID=` for the current boot ID of the kernel.

`--unit=`
`-u`

  Show data only of the specified unit. This will add a match for `_SYSTEMD_UNIT=` for the specified unit.

`-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 syslog 3, 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 level 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. This will add `PRIORITY=` matches for the specified priorities.

`--cursor=`
`-c`

  Start showing entries from the location in the journal specified by the passed cursor.

`--since=`
`--until=`

  Start showing entries on or newer than the specified date, or on or older than the specified date, respectively. Date specifications should be of the format "2012-10-30 18:17:16". If the time part is omitted, 00:00:00 is assumed. If only the seconds component is omitted, :00 is assumed. If the date component is ommitted, the current day is assumed. Alternatively the strings `yesterday`, `today`, `tomorrow` are understood, which refer to 00:00:00 of the day before the current day, the current day, or the day after the current day, respectively. `now` refers to the current time. Finally, relative times may be specified, prefixed with `-` or `+`, referring to times before or after the current time, respectively.

`--field=`
`-F`

  Print all possible data values the specified field can take in all entries of the journal.

`--directory=`
`-D`

  Takes an absolute directory path as argument. If specified journalctl will operate on the specified journal directory instead of the default runtime and system journal paths.

`--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 fields 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.

## Exit status

On success 0 is returned, a non-zero failure code otherwise.

## Environment

`$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`.

## Examples

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 expressions 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

## See Also

systemd 1, systemd-journald.service 8, systemctl 1, systemd.journal-fields 7, journald.conf 5