1 <?xml version='
1.0'
?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6 This file is part of systemd.
8 Copyright 2012 Lennart Poettering
10 systemd is free software; you can redistribute it and/or modify it
11 under the terms of the GNU Lesser General Public License as published by
12 the Free Software Foundation; either version 2.1 of the License, or
13 (at your option) any later version.
15 systemd is distributed in the hope that it will be useful, but
16 WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 Lesser General Public License for more details.
20 You should have received a copy of the GNU Lesser General Public License
21 along with systemd; If not, see <http://www.gnu.org/licenses/>.
24 <refentry id=
"journalctl"
25 xmlns:
xi=
"http://www.w3.org/2001/XInclude">
28 <title>journalctl
</title>
29 <productname>systemd
</productname>
33 <contrib>Developer
</contrib>
34 <firstname>Lennart
</firstname>
35 <surname>Poettering
</surname>
36 <email>lennart@poettering.net
</email>
42 <refentrytitle>journalctl
</refentrytitle>
43 <manvolnum>1</manvolnum>
47 <refname>journalctl
</refname>
48 <refpurpose>Query the systemd journal
</refpurpose>
53 <command>journalctl
</command>
54 <arg choice=
"opt" rep=
"repeat">OPTIONS
</arg>
55 <arg choice=
"opt" rep=
"repeat">MATCHES
</arg>
60 <title>Description
</title>
62 <para><command>journalctl
</command> may be used to query the
64 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
66 <citerefentry><refentrytitle>systemd-journald.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
68 <para>If called without parameters, it will show the full
69 contents of the journal, starting with the oldest entry
72 <para>If one or more match arguments are passed, the output is
73 filtered accordingly. A match is in the format
74 <literal>FIELD=VALUE
</literal>,
75 e.g.
<literal>_SYSTEMD_UNIT=httpd.service
</literal>, referring
76 to the components of a structured journal entry. See
77 <citerefentry><refentrytitle>systemd.journal-fields
</refentrytitle><manvolnum>7</manvolnum></citerefentry>
78 for a list of well-known fields. If multiple matches are
79 specified matching different fields, the log entries are
80 filtered by both, i.e. the resulting output will show only
81 entries matching all the specified matches of this kind. If two
82 matches apply to the same field, then they are automatically
83 matched as alternatives, i.e. the resulting output will show
84 entries matching any of the specified matches for the same
85 field. Finally, the character
<literal>+
</literal> may appears
86 as a separate word between other terms on the command line. This
87 causes all matches before and after to be combined in a
88 disjunction (i.e. logical OR).
</para>
90 <para>As shortcuts for a few types of field/value matches, file
91 paths may be specified. If a file path refers to an executable
92 file, this is equivalent to an
<literal>_EXE=
</literal> match
93 for the canonicalized binary path. Similarly, if a path refers
94 to a device node, this is equivalent to a
95 <literal>_KERNEL_DEVICE=
</literal> match for the device.
</para>
97 <para>Additional constraints may be added using options
98 <option>--boot
</option>,
<option>--unit=
</option>, etc, to
99 further limit what entries will be shown (logical AND).
</para>
101 <para>Output is interleaved from all accessible journal files,
102 whether they are rotated or currently being written, and
103 regardless of whether they belong to the system itself or are
104 accessible user journals.
</para>
106 <para>The set of journal files which will be used can be
107 modified using the
<option>--user
</option>,
108 <option>--system
</option>,
<option>--directory
</option>, and
109 <option>--file
</option> options, see below.
</para>
111 <para>All users are granted access to their private per-user
112 journals. However, by default, only root and users who are
113 members of a few special groups are granted access to the system
114 journal and the journals of other users. Members of the groups
115 <literal>systemd-journal
</literal>,
<literal>adm
</literal>, and
116 <literal>wheel
</literal> can read all journal files. Note
117 that the two latter groups traditionally have additional
118 privileges specified by the distribution. Members of the
119 <literal>wheel
</literal> group can often perform administrative
122 <para>The output is paged through
<command>less
</command> by
123 default, and long lines are
"truncated" to screen width. The
124 hidden part can be viewed by using the left-arrow and
125 right-arrow keys. Paging can be disabled; see the
126 <option>--no-pager
</option> option and the
"Environment" section
129 <para>When outputting to a tty, lines are colored according to
130 priority: lines of level ERROR and higher are colored red; lines
131 of level NOTICE and higher are highlighted; other lines are
132 displayed normally.
</para>
136 <title>Options
</title>
138 <para>The following options are understood:
</para>
142 <term><option>--no-full
</option></term>
143 <term><option>--full
</option></term>
144 <term><option>-l
</option></term>
146 <listitem><para>Ellipsize fields when they do not fit in
147 available columns. The default is to show full fields,
148 allowing them to wrap or be truncated by the pager, if one
151 <para>The old options
152 <option>-l
</option>/
<option>--full
</option> are not useful
153 anymore, except to undo
<option>--no-full
</option>.
</para>
158 <term><option>-a
</option></term>
159 <term><option>--all
</option></term>
161 <listitem><para>Show all fields in full, even if they
162 include unprintable characters or are very
163 long.
</para></listitem>
167 <term><option>-f
</option></term>
168 <term><option>--follow
</option></term>
170 <listitem><para>Show only the most recent journal entries,
171 and continuously print new entries as they are appended to
172 the journal.
</para></listitem>
176 <term><option>-e
</option></term>
177 <term><option>--pager-end
</option></term>
179 <listitem><para>Immediately jump to the end of the journal
180 inside the implied pager tool. This implies
181 <option>-n1000
</option> to guarantee that the pager will not
182 buffer logs of unbounded size. This may be overridden with
183 an explicit
<option>-n
</option> with some other numeric
184 value while
<option>-nall
</option> will disable this cap.
185 Note that this option is only supported for the
186 <citerefentry project='man-pages'
><refentrytitle>less
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
187 pager.
</para></listitem>
191 <term><option>-n
</option></term>
192 <term><option>--lines=
</option></term>
194 <listitem><para>Show the most recent journal events and
195 limit the number of events shown. If
196 <option>--follow
</option> is used, this option is
197 implied. The argument is a positive integer or
198 <literal>all
</literal> to disable line limiting. The default
199 value is
10 if no argument is given.
</para></listitem>
203 <term><option>--no-tail
</option></term>
205 <listitem><para>Show all stored output lines, even in follow
206 mode. Undoes the effect of
<option>--lines=
</option>.
211 <term><option>-r
</option></term>
212 <term><option>--reverse
</option></term>
214 <listitem><para>Reverse output so that the newest entries
215 are displayed first.
</para></listitem>
219 <term><option>-o
</option></term>
220 <term><option>--output=
</option></term>
222 <listitem><para>Controls the formatting of the journal
223 entries that are shown. Takes one of the following
228 <option>short
</option>
231 <para>is the default and generates an output that is
232 mostly identical to the formatting of classic syslog
233 files, showing one line per journal entry.
</para>
239 <option>short-iso
</option>
242 <para>is very similar, but shows ISO
8601 wallclock
249 <option>short-precise
</option>
252 <para>is very similar, but shows timestamps with full
253 microsecond precision.
</para>
259 <option>short-monotonic
</option>
262 <para>is very similar, but shows monotonic timestamps
263 instead of wallclock timestamps.
</para>
269 <option>verbose
</option>
272 <para>shows the full-structured entry items with all
279 <option>export
</option>
282 <para>serializes the journal into a binary (but mostly
283 text-based) stream suitable for backups and network
285 <ulink url=
"http://www.freedesktop.org/wiki/Software/systemd/export">Journal Export Format
</ulink>
286 for more information).
</para>
292 <option>json
</option>
295 <para>formats entries as JSON data structures, one per
297 <ulink url=
"http://www.freedesktop.org/wiki/Software/systemd/json">Journal JSON Format
</ulink>
298 for more information).
</para>
304 <option>json-pretty
</option>
307 <para>formats entries as JSON data structures, but
308 formats them in multiple lines in order to make them
309 more readable by humans.
</para>
315 <option>json-sse
</option>
318 <para>formats entries as JSON data structures, but wraps
319 them in a format suitable for
320 <ulink url=
"https://developer.mozilla.org/en-US/docs/Server-sent_events/Using_server-sent_events">Server-Sent Events
</ulink>.
330 <para>generates a very terse output, only showing the
331 actual message of each journal entry with no metadata,
332 not even a timestamp.
</para>
340 <term><option>--utc
</option></term>
342 <listitem><para>Express time in Coordinated Universal Time
343 (UTC).
</para></listitem>
347 <term><option>-x
</option></term>
348 <term><option>--catalog
</option></term>
350 <listitem><para>Augment log lines with explanation texts from
351 the message catalog. This will add explanatory help texts to
352 log messages in the output where this is available. These
353 short help texts will explain the context of an error or log
354 event, possible solutions, as well as pointers to support
355 forums, developer documentation, and any other relevant
356 manuals. Note that help texts are not available for all
357 messages, but only for selected ones. For more information on
358 the message catalog, please refer to the
359 <ulink url=
"http://www.freedesktop.org/wiki/Software/systemd/catalog">Message Catalog Developer Documentation
</ulink>.
</para>
361 <para>Note: when attaching
<command>journalctl
</command>
362 output to bug reports, please do
<emphasis>not
</emphasis> use
363 <option>-x
</option>.
</para>
368 <term><option>-q
</option></term>
369 <term><option>--quiet
</option></term>
371 <listitem><para>Suppresses all info messages
372 (i.e.
"-- Logs begin at ...",
"-- Reboot --"),
373 any warning messages regarding
374 inaccessible system journals when run as a normal
375 user.
</para></listitem>
379 <term><option>-m
</option></term>
380 <term><option>--merge
</option></term>
382 <listitem><para>Show entries interleaved from all available
383 journals, including remote ones.
</para></listitem>
387 <term><option>-b
<optional><replaceable>ID
</replaceable></optional><optional><replaceable>±offset
</replaceable></optional></option></term>
388 <term><option>--boot=
<optional><replaceable>ID
</replaceable></optional><optional><replaceable>±offset
</replaceable></optional></option></term>
390 <listitem><para>Show messages from a specific boot. This will
391 add a match for
<literal>_BOOT_ID=
</literal>.
</para>
393 <para>The argument may be empty, in which case logs for the
394 current boot will be shown.
</para>
396 <para>If the boot ID is omitted, a positive
397 <replaceable>offset
</replaceable> will look up the boots
398 starting from the beginning of the journal, and a
399 equal-or-less-than zero
<replaceable>offset
</replaceable> will
400 look up boots starting from the end of the journal. Thus,
401 <constant>1</constant> means the first boot found in the
402 journal in chronological order,
<constant>2</constant> the
403 second and so on; while
<constant>-
0</constant> is the last
404 boot,
<constant>-
1</constant> the boot before last, and so
405 on. An empty
<replaceable>offset
</replaceable> is equivalent
406 to specifying
<constant>-
0</constant>, except when the current
407 boot is not the last boot (e.g. because
408 <option>--directory
</option> was specified to look at logs
409 from a different machine).
</para>
411 <para>If the
32-character
<replaceable>ID
</replaceable> is
412 specified, it may optionally be followed by
413 <replaceable>offset
</replaceable> which identifies the boot
414 relative to the one given by boot
415 <replaceable>ID
</replaceable>. Negative values mean earlier
416 boots and a positive values mean later boots. If
417 <replaceable>offset
</replaceable> is not specified, a value of
418 zero is assumed, and the logs for the boot given by
419 <replaceable>ID
</replaceable> are shown.
</para>
424 <term><option>--list-boots
</option></term>
426 <listitem><para>Show a tabular list of boot numbers (relative to
427 the current boot), their IDs, and the timestamps of the first
428 and last message pertaining to the boot.
</para></listitem>
432 <term><option>-k
</option></term>
433 <term><option>--dmesg
</option></term>
435 <listitem><para>Show only kernel messages. This implies
436 <option>-b
</option> and adds the match
437 <literal>_TRANSPORT=kernel
</literal>.
</para></listitem>
441 <term><option>-t
</option></term>
442 <term><option>--identifier=
<replaceable>SYSLOG_IDENTIFIER
</replaceable></option></term>
444 <listitem><para>Show messages for the specified syslog
446 <replaceable>SYSLOG_IDENTIFIER
</replaceable>.
</para>
448 <para>This parameter can be specified multiple
449 times.
</para></listitem>
453 <term><option>-u
</option></term>
454 <term><option>--unit=
<replaceable>UNIT
</replaceable>|
<replaceable>PATTERN
</replaceable></option></term>
456 <listitem><para>Show messages for the specified systemd unit
457 <replaceable>UNIT
</replaceable> (such as a service unit), or
458 for any of the units matched by
459 <replaceable>PATTERN
</replaceable>. If a pattern is
460 specified, a list of unit names found in the journal is
461 compared with the specified pattern and all that match are
462 used. For each unit name, a match is added for messages from
464 (
<literal>_SYSTEMD_UNIT=
<replaceable>UNIT
</replaceable></literal>),
465 along with additional matches for messages from systemd and
466 messages about coredumps for the specified unit.
</para>
468 <para>This parameter can be specified multiple times.
</para>
473 <term><option>--user-unit=
</option></term>
475 <listitem><para>Show messages for the specified user session
476 unit. This will add a match for messages from the unit
477 (
<literal>_SYSTEMD_USER_UNIT=
</literal> and
478 <literal>_UID=
</literal>) and additional matches for messages
479 from session systemd and messages about coredumps for the
480 specified unit.
</para>
482 <para>This parameter can be specified multiple times.
</para>
487 <term><option>-p
</option></term>
488 <term><option>--priority=
</option></term>
490 <listitem><para>Filter output by message priorities or
491 priority ranges. Takes either a single numeric or textual log
492 level (i.e. between
0/
<literal>emerg
</literal> and
493 7/
<literal>debug
</literal>), or a range of numeric/text log
494 levels in the form FROM..TO. The log levels are the usual
495 syslog log levels as documented in
496 <citerefentry project='man-pages'
><refentrytitle>syslog
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
497 i.e.
<literal>emerg
</literal>Â (
0),
498 <literal>alert
</literal>Â (
1),
<literal>crit
</literal>Â (
2),
499 <literal>err
</literal>Â (
3),
<literal>warning
</literal>Â (
4),
500 <literal>notice
</literal>Â (
5),
<literal>info
</literal>Â (
6),
501 <literal>debug
</literal>Â (
7). If a single log level is
502 specified, all messages with this log level or a lower (hence
503 more important) log level are shown. If a range is specified,
504 all messages within the range are shown, including both the
505 start and the end value of the range. This will add
506 <literal>PRIORITY=
</literal> matches for the specified
507 priorities.
</para></listitem>
511 <term><option>-c
</option></term>
512 <term><option>--cursor=
</option></term>
514 <listitem><para>Start showing entries from the location in the
515 journal specified by the passed cursor.
</para></listitem>
519 <term><option>--after-cursor=
</option></term>
521 <listitem><para>Start showing entries from the location in the
522 journal
<emphasis>after
</emphasis> the location specified by
523 the this cursor. The cursor is shown when the
524 <option>--show-cursor
</option> option is used.
</para>
529 <term><option>--show-cursor
</option></term>
531 <listitem><para>The cursor is shown after the last entry after
533 <programlisting>-- cursor: s=
0639...
</programlisting>
534 <para>The format of the cursor is private
535 and subject to change.
</para></listitem>
539 <term><option>-S
</option></term>
540 <term><option>--since=
</option></term>
541 <term><option>-U
</option></term>
542 <term><option>--until=
</option></term>
544 <listitem><para>Start showing entries on or newer than the
545 specified date, or on or older than the specified date,
546 respectively. Date specifications should be of the format
547 <literal>2012-
10-
30 18:
17:
16</literal>. If the time part is
548 omitted,
<literal>00:
00:
00</literal> is assumed. If only the
549 seconds component is omitted,
<literal>:
00</literal> is
550 assumed. If the date component is omitted, the current day is
551 assumed. Alternatively the strings
552 <literal>yesterday
</literal>,
<literal>today
</literal>,
553 <literal>tomorrow
</literal> are understood, which refer to
554 00:
00:
00 of the day before the current day, the current day,
555 or the day after the current day,
556 respectively.
<literal>now
</literal> refers to the current
557 time. Finally, relative times may be specified, prefixed with
558 <literal>-
</literal> or
<literal>+
</literal>, referring to
559 times before or after the current time, respectively.
</para>
564 <term><option>-F
</option></term>
565 <term><option>--field=
</option></term>
567 <listitem><para>Print all possible data values the specified
568 field can take in all entries of the journal.
</para></listitem>
572 <term><option>--system
</option></term>
573 <term><option>--user
</option></term>
575 <listitem><para>Show messages from system services and the
576 kernel (with
<option>--system
</option>). Show messages from
577 service of current user (with
<option>--user
</option>). If
578 neither is specified, show all messages that the user can see.
583 <term><option>-M
</option></term>
584 <term><option>--machine=
</option></term>
586 <listitem><para>Show messages from a running, local
587 container. Specify a container name to connect to.
</para>
592 <term><option>-D
<replaceable>DIR
</replaceable></option></term>
593 <term><option>--directory=
<replaceable>DIR
</replaceable></option></term>
595 <listitem><para>Takes a directory path as argument. If
596 specified, journalctl will operate on the specified journal
597 directory
<replaceable>DIR
</replaceable> instead of the
598 default runtime and system journal paths.
</para></listitem>
602 <term><option>--file=
<replaceable>GLOB
</replaceable></option></term>
604 <listitem><para>Takes a file glob as an argument. If
605 specified, journalctl will operate on the specified journal
606 files matching
<replaceable>GLOB
</replaceable> instead of the
607 default runtime and system journal paths. May be specified
608 multiple times, in which case files will be suitably
609 interleaved.
</para></listitem>
613 <term><option>--root=
<replaceable>ROOT
</replaceable></option></term>
615 <listitem><para>Takes a directory path as an argument. If
616 specified, journalctl will operate on catalog file hierarchy
617 underneath the specified directory instead of the root
618 directory (e.g.
<option>--update-catalog
</option> will create
619 <filename><replaceable>ROOT
</replaceable>/var/lib/systemd/catalog/database
</filename>).
624 <term><option>--new-id128
</option></term>
626 <listitem><para>Instead of showing journal contents, generate
627 a new
128-bit ID suitable for identifying messages. This is
628 intended for usage by developers who need a new identifier for
629 a new message they introduce and want to make
630 recognizable. This will print the new ID in three different
631 formats which can be copied into source code or similar.
636 <term><option>--header
</option></term>
638 <listitem><para>Instead of showing journal contents, show
639 internal header information of the journal fields
640 accessed.
</para></listitem>
644 <term><option>--disk-usage
</option></term>
646 <listitem><para>Shows the current disk usage of all journal
647 files. This shows the sum of the disk usage of all archived
648 and active journal files.
</para></listitem>
652 <term><option>--vacuum-size=
</option></term>
653 <term><option>--vacuum-time=
</option></term>
654 <term><option>--vacuum-files=
</option></term>
656 <listitem><para>Removes archived journal files until the disk
657 space they use falls below the specified size (specified with
658 the usual
<literal>K
</literal>,
<literal>M
</literal>,
659 <literal>G
</literal>,
<literal>T
</literal> suffixes), or all
660 journal files contain no data older than the specified
661 timespan (specified with the usual
<literal>s
</literal>,
662 <literal>min
</literal>,
<literal>h
</literal>,
663 <literal>days
</literal>,
<literal>months
</literal>,
664 <literal>weeks
</literal>,
<literal>years
</literal> suffixes),
665 or no more than the specified number of separate journal files
666 remain. Note that running
<option>--vacuum-size=
</option> has
667 only indirect effect on the output shown by
668 <option>--disk-usage
</option> as the latter includes active
669 journal files, while the the vacuuming operation only operates
670 on archived journal files. Similar,
671 <option>--vacuum-files=
</option> might not actually reduce the
672 number of journal files to below the specified number, as it
673 will not remove active journal
674 files.
<option>--vacuum-size=
</option>,
675 <option>--vacuum-time=
</option> and
676 <option>--vacuum-files=
</option> may be combined in a single
677 invocation to enforce any combination of a size, a time and a
678 number of files limit on the archived journal
679 files. Specifying any of these three parameters as zero is
680 equivalent to not enforcing the specific limit, and is thus
681 redundant.
</para></listitem>
685 <term><option>--list-catalog
686 <optional><replaceable>128-bit-ID...
</replaceable></optional>
689 <listitem><para>List the contents of the message catalog as a
690 table of message IDs, plus their short description strings.
693 <para>If any
<replaceable>128-bit-ID
</replaceable>s are
694 specified, only those entries are shown.
</para>
699 <term><option>--dump-catalog
700 <optional><replaceable>128-bit-ID...
</replaceable></optional>
703 <listitem><para>Show the contents of the message catalog, with
704 entries separated by a line consisting of two dashes and the
705 ID (the format is the same as
<filename>.catalog
</filename>
708 <para>If any
<replaceable>128-bit-ID
</replaceable>s are
709 specified, only those entries are shown.
</para>
714 <term><option>--update-catalog
</option></term>
716 <listitem><para>Update the message catalog index. This command
717 needs to be executed each time new catalog files are
718 installed, removed, or updated to rebuild the binary catalog
719 index.
</para></listitem>
723 <term><option>--setup-keys
</option></term>
725 <listitem><para>Instead of showing journal contents, generate
726 a new key pair for Forward Secure Sealing (FSS). This will
727 generate a sealing key and a verification key. The sealing key
728 is stored in the journal data directory and shall remain on
729 the host. The verification key should be stored
730 externally. Refer to the
<option>Seal=
</option> option in
731 <citerefentry><refentrytitle>journald.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
732 for information on Forward Secure Sealing and for a link to a
733 refereed scholarly paper detailing the cryptographic theory it
734 is based on.
</para></listitem>
738 <term><option>--force
</option></term>
740 <listitem><para>When
<option>--setup-keys
</option> is passed
741 and Forward Secure Sealing (FSS) has already been configured,
742 recreate FSS keys.
</para></listitem>
746 <term><option>--interval=
</option></term>
748 <listitem><para>Specifies the change interval for the sealing
749 key when generating an FSS key pair with
750 <option>--setup-keys
</option>. Shorter intervals increase CPU
751 consumption but shorten the time range of undetectable journal
752 alterations. Defaults to
15min.
</para></listitem>
756 <term><option>--verify
</option></term>
758 <listitem><para>Check the journal file for internal
759 consistency. If the file has been generated with FSS enabled and
760 the FSS verification key has been specified with
761 <option>--verify-key=
</option>, authenticity of the journal file
762 is verified.
</para></listitem>
766 <term><option>--verify-key=
</option></term>
768 <listitem><para>Specifies the FSS verification key to use for
769 the
<option>--verify
</option> operation.
</para></listitem>
773 <term><option>--flush
</option></term>
775 <listitem><para>Asks the Journal daemon to flush any log data
776 stored in
<filename>/run/log/journal
</filename> into
777 <filename>/var/log/journal
</filename>, if persistent storage is
778 enabled. This call does not return until the operation is
779 complete.
</para></listitem>
783 <term><option>--rotate
</option></term>
785 <listitem><para>Asks the Journal daemon to rotate journal files.
788 <xi:include href=
"standard-options.xml" xpointer=
"help" />
789 <xi:include href=
"standard-options.xml" xpointer=
"version" />
790 <xi:include href=
"standard-options.xml" xpointer=
"no-pager" />
795 <title>Exit status
</title>
797 <para>On success,
0 is returned; otherwise, a non-zero failure
798 code is returned.
</para>
801 <xi:include href=
"less-variables.xml" />
804 <title>Examples
</title>
806 <para>Without arguments, all collected logs are shown
809 <programlisting>journalctl
</programlisting>
811 <para>With one match specified, all entries with a field matching
812 the expression are shown:
</para>
814 <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service
</programlisting>
816 <para>If two different fields are matched, only entries matching
817 both expressions at the same time are shown:
</para>
819 <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=
28097</programlisting>
821 <para>If two matches refer to the same field, all entries matching
822 either expression are shown:
</para>
824 <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _SYSTEMD_UNIT=dbus.service
</programlisting>
826 <para>If the separator
<literal>+
</literal> is used, two
827 expressions may be combined in a logical OR. The following will
828 show all messages from the Avahi service process with the PID
829 28097 plus all messages from the D-Bus service (from any of its
832 <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=
28097 + _SYSTEMD_UNIT=dbus.service
</programlisting>
834 <para>Show all logs generated by the D-Bus executable:
</para>
836 <programlisting>journalctl /usr/bin/dbus-daemon
</programlisting>
838 <para>Show all kernel logs from previous boot:
</para>
840 <programlisting>journalctl -k -b -
1</programlisting>
842 <para>Show a live log display from a system service
843 <filename>apache.service
</filename>:
</para>
845 <programlisting>journalctl -f -u apache
</programlisting>
850 <title>See Also
</title>
852 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
853 <citerefentry><refentrytitle>systemd-journald.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
854 <citerefentry><refentrytitle>systemctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
855 <citerefentry><refentrytitle>coredumpctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
856 <citerefentry><refentrytitle>systemd.journal-fields
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
857 <citerefentry><refentrytitle>journald.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>