man/journalctl.xml

   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">
   4
   5 <!--
   6   This file is part of systemd.
   7
   8   Copyright 2012 Lennart Poettering
   9
  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.
  14
  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.
  19
  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/>.
  22 -->
  23
  24   <refentry id="journalctl"
  25             xmlns:xi="http://www.w3.org/2001/XInclude">
  26
  27     <refentryinfo>
  28       <title>journalctl</title>
  29       <productname>systemd</productname>
  30
  31       <authorgroup>
  32         <author>
  33           <contrib>Developer</contrib>
  34           <firstname>Lennart</firstname>
  35           <surname>Poettering</surname>
  36           <email>lennart@poettering.net</email>
  37         </author>
  38       </authorgroup>
  39     </refentryinfo>
  40
  41     <refmeta>
  42       <refentrytitle>journalctl</refentrytitle>
  43       <manvolnum>1</manvolnum>
  44     </refmeta>
  45
  46     <refnamediv>
  47       <refname>journalctl</refname>
  48       <refpurpose>Query the systemd journal</refpurpose>
  49     </refnamediv>
  50
  51     <refsynopsisdiv>
  52       <cmdsynopsis>
  53         <command>journalctl</command>
  54         <arg choice="opt" rep="repeat">OPTIONS</arg>
  55         <arg choice="opt" rep="repeat">MATCHES</arg>
  56       </cmdsynopsis>
  57     </refsynopsisdiv>
  58
  59     <refsect1>
  60       <title>Description</title>
  61
  62       <para><command>journalctl</command> may be used to query the
  63       contents of the
  64       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  65       journal as written by
  66       <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
  67
  68       <para>If called without parameters, it will show the full
  69       contents of the journal, starting with the oldest entry
  70       collected.</para>
  71
  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>
  89
  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>
  96
  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>
 100
 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>
 105
 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>
 110
 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
 120       tasks.</para>
 121
 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
 127       below.</para>
 128
 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>
 133     </refsect1>
 134
 135     <refsect1>
 136       <title>Options</title>
 137
 138       <para>The following options are understood:</para>
 139
 140       <variablelist>
 141         <varlistentry>
 142           <term><option>--no-full</option></term>
 143           <term><option>--full</option></term>
 144           <term><option>-l</option></term>
 145
 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
 149           is used.</para>
 150
 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>
 154           </listitem>
 155         </varlistentry>
 156
 157         <varlistentry>
 158           <term><option>-a</option></term>
 159           <term><option>--all</option></term>
 160
 161           <listitem><para>Show all fields in full, even if they
 162           include unprintable characters or are very
 163           long.</para></listitem>
 164         </varlistentry>
 165
 166         <varlistentry>
 167           <term><option>-f</option></term>
 168           <term><option>--follow</option></term>
 169
 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>
 173         </varlistentry>
 174
 175         <varlistentry>
 176           <term><option>-e</option></term>
 177           <term><option>--pager-end</option></term>
 178
 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>
 188         </varlistentry>
 189
 190         <varlistentry>
 191           <term><option>-n</option></term>
 192           <term><option>--lines=</option></term>
 193
 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>
 200         </varlistentry>
 201
 202         <varlistentry>
 203           <term><option>--no-tail</option></term>
 204
 205           <listitem><para>Show all stored output lines, even in follow
 206           mode. Undoes the effect of <option>--lines=</option>.
 207           </para></listitem>
 208         </varlistentry>
 209
 210         <varlistentry>
 211           <term><option>-r</option></term>
 212           <term><option>--reverse</option></term>
 213
 214           <listitem><para>Reverse output so that the newest entries
 215           are displayed first.</para></listitem>
 216         </varlistentry>
 217
 218         <varlistentry>
 219           <term><option>-o</option></term>
 220           <term><option>--output=</option></term>
 221
 222           <listitem><para>Controls the formatting of the journal
 223           entries that are shown. Takes one of the following
 224           options:</para>
 225           <variablelist>
 226             <varlistentry>
 227               <term>
 228                 <option>short</option>
 229               </term>
 230               <listitem>
 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>
 234               </listitem>
 235             </varlistentry>
 236
 237             <varlistentry>
 238               <term>
 239                 <option>short-iso</option>
 240               </term>
 241               <listitem>
 242                 <para>is very similar, but shows ISO 8601 wallclock
 243                 timestamps.</para>
 244               </listitem>
 245             </varlistentry>
 246
 247             <varlistentry>
 248               <term>
 249                 <option>short-precise</option>
 250               </term>
 251               <listitem>
 252                 <para>is very similar, but shows timestamps with full
 253                 microsecond precision.</para>
 254               </listitem>
 255             </varlistentry>
 256
 257             <varlistentry>
 258               <term>
 259                 <option>short-monotonic</option>
 260               </term>
 261               <listitem>
 262                 <para>is very similar, but shows monotonic timestamps
 263                 instead of wallclock timestamps.</para>
 264               </listitem>
 265             </varlistentry>
 266
 267             <varlistentry>
 268               <term>
 269                 <option>verbose</option>
 270               </term>
 271               <listitem>
 272                 <para>shows the full-structured entry items with all
 273                 fields.</para>
 274               </listitem>
 275             </varlistentry>
 276
 277             <varlistentry>
 278               <term>
 279                 <option>export</option>
 280               </term>
 281               <listitem>
 282                 <para>serializes the journal into a binary (but mostly
 283                 text-based) stream suitable for backups and network
 284                 transfer (see
 285                 <ulink url="http://www.freedesktop.org/wiki/Software/systemd/export">Journal Export Format</ulink>
 286                 for more information).</para>
 287               </listitem>
 288             </varlistentry>
 289
 290             <varlistentry>
 291               <term>
 292                 <option>json</option>
 293               </term>
 294               <listitem>
 295                 <para>formats entries as JSON data structures, one per
 296                 line (see
 297                 <ulink url="http://www.freedesktop.org/wiki/Software/systemd/json">Journal JSON Format</ulink>
 298                 for more information).</para>
 299               </listitem>
 300             </varlistentry>
 301
 302             <varlistentry>
 303               <term>
 304                 <option>json-pretty</option>
 305               </term>
 306               <listitem>
 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>
 310               </listitem>
 311             </varlistentry>
 312
 313             <varlistentry>
 314               <term>
 315                 <option>json-sse</option>
 316               </term>
 317               <listitem>
 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>.
 321                 </para>
 322               </listitem>
 323             </varlistentry>
 324
 325             <varlistentry>
 326               <term>
 327                 <option>cat</option>
 328               </term>
 329               <listitem>
 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>
 333               </listitem>
 334             </varlistentry>
 335           </variablelist>
 336         </listitem>
 337       </varlistentry>
 338
 339       <varlistentry>
 340         <term><option>--utc</option></term>
 341
 342         <listitem><para>Express time in Coordinated Universal Time
 343         (UTC).</para></listitem>
 344       </varlistentry>
 345
 346       <varlistentry>
 347         <term><option>-x</option></term>
 348         <term><option>--catalog</option></term>
 349
 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>
 360
 361         <para>Note: when attaching <command>journalctl</command>
 362         output to bug reports, please do <emphasis>not</emphasis> use
 363         <option>-x</option>.</para>
 364         </listitem>
 365       </varlistentry>
 366
 367       <varlistentry>
 368         <term><option>-q</option></term>
 369         <term><option>--quiet</option></term>
 370
 371         <listitem><para>Suppresses any warning messages regarding
 372         inaccessible system journals when run as a normal
 373         user.</para></listitem>
 374       </varlistentry>
 375
 376       <varlistentry>
 377         <term><option>-m</option></term>
 378         <term><option>--merge</option></term>
 379
 380         <listitem><para>Show entries interleaved from all available
 381         journals, including remote ones.</para></listitem>
 382       </varlistentry>
 383
 384       <varlistentry>
 385         <term><option>-b <optional><replaceable>ID</replaceable></optional><optional><replaceable>±offset</replaceable></optional></option></term>
 386         <term><option>--boot=<optional><replaceable>ID</replaceable></optional><optional><replaceable>±offset</replaceable></optional></option></term>
 387
 388         <listitem><para>Show messages from a specific boot. This will
 389         add a match for <literal>_BOOT_ID=</literal>.</para>
 390
 391         <para>The argument may be empty, in which case logs for the
 392         current boot will be shown.</para>
 393
 394         <para>If the boot ID is omitted, a positive
 395         <replaceable>offset</replaceable> will look up the boots
 396         starting from the beginning of the journal, and a
 397         equal-or-less-than zero <replaceable>offset</replaceable> will
 398         look up boots starting from the end of the journal. Thus,
 399         <constant>1</constant> means the first boot found in the
 400         journal in chronological order, <constant>2</constant> the
 401         second and so on; while <constant>-0</constant> is the last
 402         boot, <constant>-1</constant> the boot before last, and so
 403         on. An empty <replaceable>offset</replaceable> is equivalent
 404         to specifying <constant>-0</constant>, except when the current
 405         boot is not the last boot (e.g. because
 406         <option>--directory</option> was specified to look at logs
 407         from a different machine).</para>
 408
 409         <para>If the 32-character <replaceable>ID</replaceable> is
 410         specified, it may optionally be followed by
 411         <replaceable>offset</replaceable> which identifies the boot
 412         relative to the one given by boot
 413         <replaceable>ID</replaceable>. Negative values mean earlier
 414         boots and a positive values mean later boots. If
 415         <replaceable>offset</replaceable> is not specified, a value of
 416         zero is assumed, and the logs for the boot given by
 417         <replaceable>ID</replaceable> are shown.</para>
 418         </listitem>
 419       </varlistentry>
 420
 421       <varlistentry>
 422         <term><option>--list-boots</option></term>
 423
 424         <listitem><para>Show a tabular list of boot numbers (relative to
 425         the current boot), their IDs, and the timestamps of the first
 426         and last message pertaining to the boot.</para></listitem>
 427       </varlistentry>
 428
 429       <varlistentry>
 430         <term><option>-k</option></term>
 431         <term><option>--dmesg</option></term>
 432
 433         <listitem><para>Show only kernel messages. This implies
 434         <option>-b</option> and adds the match
 435         <literal>_TRANSPORT=kernel</literal>.</para></listitem>
 436       </varlistentry>
 437
 438       <varlistentry>
 439         <term><option>-t</option></term>
 440         <term><option>--identifier=<replaceable>SYSLOG_IDENTIFIER</replaceable>|<replaceable>PATTERN</replaceable></option></term>
 441
 442         <listitem><para>Show messages for the specified syslog
 443         identifier <replaceable>SYSLOG_IDENTIFIER</replaceable>, or
 444         for any of the messages with a
 445         <literal>SYSLOG_IDENTIFIER</literal> matched by
 446         <replaceable>PATTERN</replaceable>.</para>
 447
 448         <para>This parameter can be specified multiple
 449         times.</para></listitem>
 450       </varlistentry>
 451
 452       <varlistentry>
 453         <term><option>-u</option></term>
 454         <term><option>--unit=<replaceable>UNIT</replaceable>|<replaceable>PATTERN</replaceable></option></term>
 455
 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
 463         the unit
 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>
 467
 468         <para>This parameter can be specified multiple times.</para>
 469         </listitem>
 470       </varlistentry>
 471
 472       <varlistentry>
 473         <term><option>--user-unit=</option></term>
 474
 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>
 481
 482         <para>This parameter can be specified multiple times.</para>
 483         </listitem>
 484       </varlistentry>
 485
 486       <varlistentry>
 487         <term><option>-p</option></term>
 488         <term><option>--priority=</option></term>
 489
 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> (0),
 498         <literal>alert</literal> (1), <literal>crit</literal> (2),
 499         <literal>err</literal> (3), <literal>warning</literal> (4),
 500         <literal>notice</literal> (5), <literal>info</literal> (6),
 501         <literal>debug</literal> (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>
 508       </varlistentry>
 509
 510       <varlistentry>
 511         <term><option>-c</option></term>
 512         <term><option>--cursor=</option></term>
 513
 514         <listitem><para>Start showing entries from the location in the
 515         journal specified by the passed cursor.</para></listitem>
 516       </varlistentry>
 517
 518       <varlistentry>
 519         <term><option>--after-cursor=</option></term>
 520
 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>
 525         </listitem>
 526       </varlistentry>
 527
 528       <varlistentry>
 529         <term><option>--show-cursor</option></term>
 530
 531         <listitem><para>The cursor is shown after the last entry after
 532         two dashes:</para>
 533         <programlisting>-- cursor: s=0639...</programlisting>
 534         <para>The format of the cursor is private
 535         and subject to change.</para></listitem>
 536       </varlistentry>
 537
 538       <varlistentry>
 539         <term><option>--since=</option></term>
 540         <term><option>--until=</option></term>
 541
 542         <listitem><para>Start showing entries on or newer than the
 543         specified date, or on or older than the specified date,
 544         respectively. Date specifications should be of the format
 545         <literal>2012-10-30 18:17:16</literal>.  If the time part is
 546         omitted, <literal>00:00:00</literal> is assumed.  If only the
 547         seconds component is omitted, <literal>:00</literal> is
 548         assumed. If the date component is omitted, the current day is
 549         assumed. Alternatively the strings
 550         <literal>yesterday</literal>, <literal>today</literal>,
 551         <literal>tomorrow</literal> are understood, which refer to
 552         00:00:00 of the day before the current day, the current day,
 553         or the day after the current day,
 554         respectively. <literal>now</literal> refers to the current
 555         time. Finally, relative times may be specified, prefixed with
 556         <literal>-</literal> or <literal>+</literal>, referring to
 557         times before or after the current time, respectively.</para>
 558         </listitem>
 559       </varlistentry>
 560
 561       <varlistentry>
 562         <term><option>-F</option></term>
 563         <term><option>--field=</option></term>
 564
 565         <listitem><para>Print all possible data values the specified
 566         field can take in all entries of the journal.</para></listitem>
 567       </varlistentry>
 568
 569       <varlistentry>
 570         <term><option>--system</option></term>
 571         <term><option>--user</option></term>
 572
 573         <listitem><para>Show messages from system services and the
 574         kernel (with <option>--system</option>). Show messages from
 575         service of current user (with <option>--user</option>).  If
 576         neither is specified, show all messages that the user can see.
 577         </para></listitem>
 578       </varlistentry>
 579
 580       <varlistentry>
 581         <term><option>-M</option></term>
 582         <term><option>--machine=</option></term>
 583
 584         <listitem><para>Show messages from a running, local
 585         container. Specify a container name to connect to.</para>
 586         </listitem>
 587       </varlistentry>
 588
 589       <varlistentry>
 590         <term><option>-D <replaceable>DIR</replaceable></option></term>
 591         <term><option>--directory=<replaceable>DIR</replaceable></option></term>
 592
 593         <listitem><para>Takes a directory path as argument. If
 594         specified, journalctl will operate on the specified journal
 595         directory <replaceable>DIR</replaceable> instead of the
 596         default runtime and system journal paths.</para></listitem>
 597       </varlistentry>
 598
 599       <varlistentry>
 600         <term><option>--file=<replaceable>GLOB</replaceable></option></term>
 601
 602         <listitem><para>Takes a file glob as an argument. If
 603         specified, journalctl will operate on the specified journal
 604         files matching <replaceable>GLOB</replaceable> instead of the
 605         default runtime and system journal paths. May be specified
 606         multiple times, in which case files will be suitably
 607         interleaved.</para></listitem>
 608       </varlistentry>
 609
 610       <varlistentry>
 611         <term><option>--root=<replaceable>ROOT</replaceable></option></term>
 612
 613         <listitem><para>Takes a directory path as an argument. If
 614         specified, journalctl will operate on catalog file hierarchy
 615         underneath the specified directory instead of the root
 616         directory (e.g. <option>--update-catalog</option> will create
 617         <filename><replaceable>ROOT</replaceable>/var/lib/systemd/catalog/database</filename>).
 618         </para></listitem>
 619       </varlistentry>
 620
 621       <varlistentry>
 622         <term><option>--new-id128</option></term>
 623
 624         <listitem><para>Instead of showing journal contents, generate
 625         a new 128-bit ID suitable for identifying messages. This is
 626         intended for usage by developers who need a new identifier for
 627         a new message they introduce and want to make
 628         recognizable. This will print the new ID in three different
 629         formats which can be copied into source code or similar.
 630         </para></listitem>
 631       </varlistentry>
 632
 633       <varlistentry>
 634         <term><option>--header</option></term>
 635
 636         <listitem><para>Instead of showing journal contents, show
 637         internal header information of the journal fields
 638         accessed.</para></listitem>
 639       </varlistentry>
 640
 641       <varlistentry>
 642         <term><option>--disk-usage</option></term>
 643
 644         <listitem><para>Shows the current disk usage of all journal
 645         files. This shows the sum of the disk usage of all archived
 646         and active journal files.</para></listitem>
 647       </varlistentry>
 648
 649       <varlistentry>
 650         <term><option>--vacuum-size=</option></term>
 651         <term><option>--vacuum-time=</option></term>
 652         <term><option>--vacuum-files=</option></term>
 653
 654         <listitem><para>Removes archived journal files until the disk
 655         space they use falls below the specified size (specified with
 656         the usual <literal>K</literal>, <literal>M</literal>,
 657         <literal>G</literal>, <literal>T</literal> suffixes), or all
 658         journal files contain no data older than the specified
 659         timespan (specified with the usual <literal>s</literal>,
 660         <literal>min</literal>, <literal>h</literal>,
 661         <literal>days</literal>, <literal>months</literal>,
 662         <literal>weeks</literal>, <literal>years</literal> suffixes),
 663         or no more than the specified number of separate journal files
 664         remain. Note that running <option>--vacuum-size=</option> has
 665         only indirect effect on the output shown by
 666         <option>--disk-usage</option> as the latter includes active
 667         journal files, while the the vacuuming operation only operates
 668         on archived journal files. Similar,
 669         <option>--vacuum-files=</option> might not actually reduce the
 670         number of journal files to below the specified number, as it
 671         will not remove active journal
 672         files. <option>--vacuum-size=</option>,
 673         <option>--vacuum-time=</option> and
 674         <option>--vacuum-files=</option> may be combined in a single
 675         invocation to enforce any combination of a size, a time and a
 676         number of files limit on the archived journal
 677         files. Specifying any of these three parameters as zero is
 678         equivalent to not enforcing the specific limit, and is thus
 679         redundant.</para></listitem>
 680       </varlistentry>
 681
 682       <varlistentry>
 683         <term><option>--list-catalog
 684         <optional><replaceable>128-bit-ID...</replaceable></optional>
 685         </option></term>
 686
 687         <listitem><para>List the contents of the message catalog as a
 688         table of message IDs, plus their short description strings.
 689         </para>
 690
 691         <para>If any <replaceable>128-bit-ID</replaceable>s are
 692         specified, only those entries are shown.</para>
 693         </listitem>
 694       </varlistentry>
 695
 696       <varlistentry>
 697         <term><option>--dump-catalog
 698         <optional><replaceable>128-bit-ID...</replaceable></optional>
 699         </option></term>
 700
 701         <listitem><para>Show the contents of the message catalog, with
 702         entries separated by a line consisting of two dashes and the
 703         ID (the format is the same as <filename>.catalog</filename>
 704         files).</para>
 705
 706         <para>If any <replaceable>128-bit-ID</replaceable>s are
 707         specified, only those entries are shown.</para>
 708         </listitem>
 709       </varlistentry>
 710
 711       <varlistentry>
 712         <term><option>--update-catalog</option></term>
 713
 714         <listitem><para>Update the message catalog index. This command
 715         needs to be executed each time new catalog files are
 716         installed, removed, or updated to rebuild the binary catalog
 717         index.</para></listitem>
 718       </varlistentry>
 719
 720       <varlistentry>
 721         <term><option>--setup-keys</option></term>
 722
 723         <listitem><para>Instead of showing journal contents, generate
 724         a new key pair for Forward Secure Sealing (FSS). This will
 725         generate a sealing key and a verification key. The sealing key
 726         is stored in the journal data directory and shall remain on
 727         the host. The verification key should be stored
 728         externally. Refer to the <option>Seal=</option> option in
 729         <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 730         for information on Forward Secure Sealing and for a link to a
 731         refereed scholarly paper detailing the cryptographic theory it
 732         is based on.</para></listitem>
 733       </varlistentry>
 734
 735       <varlistentry>
 736         <term><option>--force</option></term>
 737
 738         <listitem><para>When <option>--setup-keys</option> is passed
 739         and Forward Secure Sealing (FSS) has already been configured,
 740         recreate FSS keys.</para></listitem>
 741       </varlistentry>
 742
 743       <varlistentry>
 744         <term><option>--interval=</option></term>
 745
 746         <listitem><para>Specifies the change interval for the sealing
 747         key when generating an FSS key pair with
 748         <option>--setup-keys</option>. Shorter intervals increase CPU
 749         consumption but shorten the time range of undetectable journal
 750         alterations. Defaults to 15min.</para></listitem>
 751       </varlistentry>
 752
 753       <varlistentry>
 754         <term><option>--verify</option></term>
 755
 756         <listitem><para>Check the journal file for internal
 757         consistency. If the file has been generated with FSS enabled and
 758         the FSS verification key has been specified with
 759         <option>--verify-key=</option>, authenticity of the journal file
 760         is verified.</para></listitem>
 761       </varlistentry>
 762
 763       <varlistentry>
 764         <term><option>--verify-key=</option></term>
 765
 766         <listitem><para>Specifies the FSS verification key to use for
 767         the <option>--verify</option> operation.</para></listitem>
 768       </varlistentry>
 769
 770       <varlistentry>
 771         <term><option>--flush</option></term>
 772
 773         <listitem><para>Asks the Journal daemon to flush any log data
 774         stored in <filename>/run/log/journal</filename> into
 775         <filename>/var/log/journal</filename>, if persistent storage is
 776         enabled. This call does not return until the operation is
 777         complete.</para></listitem>
 778       </varlistentry>
 779
 780       <varlistentry>
 781         <term><option>--rotate</option></term>
 782
 783         <listitem><para>Asks the Journal daemon to rotate journal files.
 784         </para></listitem>
 785       </varlistentry>
 786       <xi:include href="standard-options.xml" xpointer="help" />
 787       <xi:include href="standard-options.xml" xpointer="version" />
 788       <xi:include href="standard-options.xml" xpointer="no-pager" />
 789     </variablelist>
 790   </refsect1>
 791
 792   <refsect1>
 793     <title>Exit status</title>
 794
 795     <para>On success, 0 is returned; otherwise, a non-zero failure
 796     code is returned.</para>
 797   </refsect1>
 798
 799   <xi:include href="less-variables.xml" />
 800
 801   <refsect1>
 802     <title>Examples</title>
 803
 804     <para>Without arguments, all collected logs are shown
 805     unfiltered:</para>
 806
 807     <programlisting>journalctl</programlisting>
 808
 809     <para>With one match specified, all entries with a field matching
 810     the expression are shown:</para>
 811
 812     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service</programlisting>
 813
 814     <para>If two different fields are matched, only entries matching
 815     both expressions at the same time are shown:</para>
 816
 817     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097</programlisting>
 818
 819     <para>If two matches refer to the same field, all entries matching
 820     either expression are shown:</para>
 821
 822     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _SYSTEMD_UNIT=dbus.service</programlisting>
 823
 824     <para>If the separator <literal>+</literal> is used, two
 825     expressions may be combined in a logical OR. The following will
 826     show all messages from the Avahi service process with the PID
 827     28097 plus all messages from the D-Bus service (from any of its
 828     processes):</para>
 829
 830     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097 + _SYSTEMD_UNIT=dbus.service</programlisting>
 831
 832     <para>Show all logs generated by the D-Bus executable:</para>
 833
 834     <programlisting>journalctl /usr/bin/dbus-daemon</programlisting>
 835
 836     <para>Show all kernel logs from previous boot:</para>
 837
 838     <programlisting>journalctl -k -b -1</programlisting>
 839
 840     <para>Show a live log display from a system service
 841     <filename>apache.service</filename>:</para>
 842
 843     <programlisting>journalctl -f -u apache</programlisting>
 844
 845   </refsect1>
 846
 847   <refsect1>
 848     <title>See Also</title>
 849     <para>
 850       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 851       <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 852       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 853       <citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 854       <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 855       <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 856     </para>
 857   </refsect1>
 858 </refentry>