man/journalctl.xml

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  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 appear
  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>It is also possible to filter the entries by specifying an
  91       absolute file path as an argument. The file path may be a file or
  92       a symbolic link and the file must exist at the time of the query. If a
  93       file path refers to an executable binary, an <literal>_EXE=</literal>
  94       match for the canonicalized binary path is added to the query. If a
  95       file path refers to an executable script, a <literal>_COMM=</literal>
  96       match for the script name is added to the query. If a file path
  97       refers to a device node, <literal>_KERNEL_DEVICE=</literal> matches for
  98       the kernel name of the device and for each of its ancestor devices is
  99       added to the query. Symbolic links are dereferenced, kernel names are
 100       synthesized, and parent devices are identified from the environment at
 101       the time of the query. In general, a device node is the best proxy for
 102       an actual device, as log entries do not usually contain fields that
 103       identify an actual device. For the resulting log entries to be correct
 104       for the actual device, the relevant parts of the environment at the time
 105       the entry was logged, in particular the actual device corresponding to
 106       the device node, must have been the same as those at the time of the
 107       query. Because device nodes generally change their corresponding devices
 108       across reboots, specifying a device node path causes the resulting
 109       entries to be restricted to those from the current boot.</para>
 110
 111       <para>Additional constraints may be added using options
 112       <option>--boot</option>, <option>--unit=</option>, etc., to
 113       further limit what entries will be shown (logical AND).</para>
 114
 115       <para>Output is interleaved from all accessible journal files,
 116       whether they are rotated or currently being written, and
 117       regardless of whether they belong to the system itself or are
 118       accessible user journals.</para>
 119
 120       <para>The set of journal files which will be used can be
 121       modified using the <option>--user</option>,
 122       <option>--system</option>, <option>--directory</option>, and
 123       <option>--file</option> options, see below.</para>
 124
 125       <para>All users are granted access to their private per-user
 126       journals. However, by default, only root and users who are
 127       members of a few special groups are granted access to the system
 128       journal and the journals of other users. Members of the groups
 129       <literal>systemd-journal</literal>, <literal>adm</literal>, and
 130       <literal>wheel</literal> can read all journal files. Note
 131       that the two latter groups traditionally have additional
 132       privileges specified by the distribution. Members of the
 133       <literal>wheel</literal> group can often perform administrative
 134       tasks.</para>
 135
 136       <para>The output is paged through <command>less</command> by
 137       default, and long lines are "truncated" to screen width. The
 138       hidden part can be viewed by using the left-arrow and
 139       right-arrow keys. Paging can be disabled; see the
 140       <option>--no-pager</option> option and the "Environment" section
 141       below.</para>
 142
 143       <para>When outputting to a tty, lines are colored according to
 144       priority: lines of level ERROR and higher are colored red; lines
 145       of level NOTICE and higher are highlighted; other lines are
 146       displayed normally.</para>
 147     </refsect1>
 148
 149     <refsect1>
 150       <title>Options</title>
 151
 152       <para>The following options are understood:</para>
 153
 154       <variablelist>
 155         <varlistentry>
 156           <term><option>--no-full</option></term>
 157           <term><option>--full</option></term>
 158           <term><option>-l</option></term>
 159
 160           <listitem><para>Ellipsize fields when they do not fit in
 161           available columns.  The default is to show full fields,
 162           allowing them to wrap or be truncated by the pager, if one
 163           is used.</para>
 164
 165           <para>The old options
 166           <option>-l</option>/<option>--full</option> are not useful
 167           anymore, except to undo <option>--no-full</option>.</para>
 168           </listitem>
 169         </varlistentry>
 170
 171         <varlistentry>
 172           <term><option>-a</option></term>
 173           <term><option>--all</option></term>
 174
 175           <listitem><para>Show all fields in full, even if they
 176           include unprintable characters or are very
 177           long.</para></listitem>
 178         </varlistentry>
 179
 180         <varlistentry>
 181           <term><option>-f</option></term>
 182           <term><option>--follow</option></term>
 183
 184           <listitem><para>Show only the most recent journal entries,
 185           and continuously print new entries as they are appended to
 186           the journal.</para></listitem>
 187         </varlistentry>
 188
 189         <varlistentry>
 190           <term><option>-e</option></term>
 191           <term><option>--pager-end</option></term>
 192
 193           <listitem><para>Immediately jump to the end of the journal
 194           inside the implied pager tool. This implies
 195           <option>-n1000</option> to guarantee that the pager will not
 196           buffer logs of unbounded size. This may be overridden with
 197           an explicit <option>-n</option> with some other numeric
 198           value, while <option>-nall</option> will disable this cap.
 199           Note that this option is only supported for the
 200           <citerefentry project='man-pages'><refentrytitle>less</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 201           pager.</para></listitem>
 202         </varlistentry>
 203
 204         <varlistentry>
 205           <term><option>-n</option></term>
 206           <term><option>--lines=</option></term>
 207
 208           <listitem><para>Show the most recent journal events and
 209           limit the number of events shown. If
 210           <option>--follow</option> is used, this option is
 211           implied. The argument is a positive integer or
 212           <literal>all</literal> to disable line limiting. The default
 213           value is 10 if no argument is given.</para></listitem>
 214         </varlistentry>
 215
 216         <varlistentry>
 217           <term><option>--no-tail</option></term>
 218
 219           <listitem><para>Show all stored output lines, even in follow
 220           mode. Undoes the effect of <option>--lines=</option>.
 221           </para></listitem>
 222         </varlistentry>
 223
 224         <varlistentry>
 225           <term><option>-r</option></term>
 226           <term><option>--reverse</option></term>
 227
 228           <listitem><para>Reverse output so that the newest entries
 229           are displayed first.</para></listitem>
 230         </varlistentry>
 231
 232         <varlistentry>
 233           <term><option>-o</option></term>
 234           <term><option>--output=</option></term>
 235
 236           <listitem><para>Controls the formatting of the journal
 237           entries that are shown. Takes one of the following
 238           options:</para>
 239           <variablelist>
 240             <varlistentry>
 241               <term>
 242                 <option>short</option>
 243               </term>
 244               <listitem>
 245                 <para>is the default and generates an output that is
 246                 mostly identical to the formatting of classic syslog
 247                 files, showing one line per journal entry.</para>
 248               </listitem>
 249             </varlistentry>
 250
 251             <varlistentry>
 252               <term>
 253                 <option>short-full</option>
 254               </term>
 255               <listitem>
 256                 <para>is very similar, but shows timestamps in the format the <option>--since=</option> and
 257                 <option>--until=</option> options accept. Unlike the timestamp information shown in
 258                 <option>short</option> output mode this mode includes weekday, year and timezone information in the
 259                 output, and is locale-independent.</para>
 260               </listitem>
 261             </varlistentry>
 262
 263             <varlistentry>
 264               <term>
 265                 <option>short-iso</option>
 266               </term>
 267               <listitem>
 268                 <para>is very similar, but shows ISO 8601 wallclock
 269                 timestamps.</para>
 270               </listitem>
 271             </varlistentry>
 272
 273             <varlistentry>
 274               <term>
 275                 <option>short-precise</option>
 276               </term>
 277               <listitem>
 278                 <para>is very similar, but shows timestamps with full
 279                 microsecond precision.</para>
 280               </listitem>
 281             </varlistentry>
 282
 283             <varlistentry>
 284               <term>
 285                 <option>short-monotonic</option>
 286               </term>
 287               <listitem>
 288                 <para>is very similar, but shows monotonic timestamps
 289                 instead of wallclock timestamps.</para>
 290               </listitem>
 291             </varlistentry>
 292
 293             <varlistentry>
 294               <term>
 295                 <option>short-unix</option>
 296               </term>
 297               <listitem>
 298                 <para>is very similar, but shows seconds passed since January 1st 1970 UTC instead of wallclock
 299                 timestamps ("UNIX time"). The time is shown with microsecond accuracy.</para>
 300               </listitem>
 301             </varlistentry>
 302
 303             <varlistentry>
 304               <term>
 305                 <option>verbose</option>
 306               </term>
 307               <listitem>
 308                 <para>shows the full-structured entry items with all
 309                 fields.</para>
 310               </listitem>
 311             </varlistentry>
 312
 313             <varlistentry>
 314               <term>
 315                 <option>export</option>
 316               </term>
 317               <listitem>
 318                 <para>serializes the journal into a binary (but mostly
 319                 text-based) stream suitable for backups and network
 320                 transfer (see
 321                 <ulink url="http://www.freedesktop.org/wiki/Software/systemd/export">Journal Export Format</ulink>
 322                 for more information).</para>
 323               </listitem>
 324             </varlistentry>
 325
 326             <varlistentry>
 327               <term>
 328                 <option>json</option>
 329               </term>
 330               <listitem>
 331                 <para>formats entries as JSON data structures, one per
 332                 line (see
 333                 <ulink url="http://www.freedesktop.org/wiki/Software/systemd/json">Journal JSON Format</ulink>
 334                 for more information).</para>
 335               </listitem>
 336             </varlistentry>
 337
 338             <varlistentry>
 339               <term>
 340                 <option>json-pretty</option>
 341               </term>
 342               <listitem>
 343                 <para>formats entries as JSON data structures, but
 344                 formats them in multiple lines in order to make them
 345                 more readable by humans.</para>
 346               </listitem>
 347             </varlistentry>
 348
 349             <varlistentry>
 350               <term>
 351                 <option>json-sse</option>
 352               </term>
 353               <listitem>
 354                 <para>formats entries as JSON data structures, but wraps
 355                 them in a format suitable for
 356                 <ulink url="https://developer.mozilla.org/en-US/docs/Server-sent_events/Using_server-sent_events">Server-Sent Events</ulink>.
 357                 </para>
 358               </listitem>
 359             </varlistentry>
 360
 361             <varlistentry>
 362               <term>
 363                 <option>cat</option>
 364               </term>
 365               <listitem>
 366                 <para>generates a very terse output, only showing the
 367                 actual message of each journal entry with no metadata,
 368                 not even a timestamp.</para>
 369               </listitem>
 370             </varlistentry>
 371           </variablelist>
 372         </listitem>
 373       </varlistentry>
 374
 375       <varlistentry>
 376         <term><option>--utc</option></term>
 377
 378         <listitem><para>Express time in Coordinated Universal Time
 379         (UTC).</para></listitem>
 380       </varlistentry>
 381
 382       <varlistentry>
 383         <term><option>--no-hostname</option></term>
 384
 385         <listitem><para>Don't show the hostname field of log messages originating from the local host. This switch only
 386         has an effect on the <option>short</option> family of output modes (see above).</para></listitem>
 387       </varlistentry>
 388
 389       <varlistentry>
 390         <term><option>-x</option></term>
 391         <term><option>--catalog</option></term>
 392
 393         <listitem><para>Augment log lines with explanation texts from
 394         the message catalog. This will add explanatory help texts to
 395         log messages in the output where this is available. These
 396         short help texts will explain the context of an error or log
 397         event, possible solutions, as well as pointers to support
 398         forums, developer documentation, and any other relevant
 399         manuals. Note that help texts are not available for all
 400         messages, but only for selected ones. For more information on
 401         the message catalog, please refer to the
 402         <ulink url="http://www.freedesktop.org/wiki/Software/systemd/catalog">Message Catalog Developer Documentation</ulink>.</para>
 403
 404         <para>Note: when attaching <command>journalctl</command>
 405         output to bug reports, please do <emphasis>not</emphasis> use
 406         <option>-x</option>.</para>
 407         </listitem>
 408       </varlistentry>
 409
 410       <varlistentry>
 411         <term><option>-q</option></term>
 412         <term><option>--quiet</option></term>
 413
 414         <listitem><para>Suppresses all info messages
 415         (i.e. "-- Logs begin at …", "-- Reboot --"),
 416         any warning messages regarding
 417         inaccessible system journals when run as a normal
 418         user.</para></listitem>
 419       </varlistentry>
 420
 421       <varlistentry>
 422         <term><option>-m</option></term>
 423         <term><option>--merge</option></term>
 424
 425         <listitem><para>Show entries interleaved from all available
 426         journals, including remote ones.</para></listitem>
 427       </varlistentry>
 428
 429       <varlistentry>
 430         <term><option>-b <optional><replaceable>ID</replaceable></optional><optional><replaceable>±offset</replaceable></optional></option></term>
 431         <term><option>--boot=<optional><replaceable>ID</replaceable></optional><optional><replaceable>±offset</replaceable></optional></option></term>
 432
 433         <listitem><para>Show messages from a specific boot. This will
 434         add a match for <literal>_BOOT_ID=</literal>.</para>
 435
 436         <para>The argument may be empty, in which case logs for the
 437         current boot will be shown.</para>
 438
 439         <para>If the boot ID is omitted, a positive
 440         <replaceable>offset</replaceable> will look up the boots
 441         starting from the beginning of the journal, and an
 442         equal-or-less-than zero <replaceable>offset</replaceable> will
 443         look up boots starting from the end of the journal. Thus,
 444         <constant>1</constant> means the first boot found in the
 445         journal in chronological order, <constant>2</constant> the
 446         second and so on; while <constant>-0</constant> is the last
 447         boot, <constant>-1</constant> the boot before last, and so
 448         on. An empty <replaceable>offset</replaceable> is equivalent
 449         to specifying <constant>-0</constant>, except when the current
 450         boot is not the last boot (e.g. because
 451         <option>--directory</option> was specified to look at logs
 452         from a different machine).</para>
 453
 454         <para>If the 32-character <replaceable>ID</replaceable> is
 455         specified, it may optionally be followed by
 456         <replaceable>offset</replaceable> which identifies the boot
 457         relative to the one given by boot
 458         <replaceable>ID</replaceable>. Negative values mean earlier
 459         boots and positive values mean later boots. If
 460         <replaceable>offset</replaceable> is not specified, a value of
 461         zero is assumed, and the logs for the boot given by
 462         <replaceable>ID</replaceable> are shown.</para>
 463         </listitem>
 464       </varlistentry>
 465
 466       <varlistentry>
 467         <term><option>--list-boots</option></term>
 468
 469         <listitem><para>Show a tabular list of boot numbers (relative to
 470         the current boot), their IDs, and the timestamps of the first
 471         and last message pertaining to the boot.</para></listitem>
 472       </varlistentry>
 473
 474       <varlistentry>
 475         <term><option>-k</option></term>
 476         <term><option>--dmesg</option></term>
 477
 478         <listitem><para>Show only kernel messages. This implies
 479         <option>-b</option> and adds the match
 480         <literal>_TRANSPORT=kernel</literal>.</para></listitem>
 481       </varlistentry>
 482
 483       <varlistentry>
 484         <term><option>-t</option></term>
 485         <term><option>--identifier=<replaceable>SYSLOG_IDENTIFIER</replaceable></option></term>
 486
 487         <listitem><para>Show messages for the specified syslog
 488         identifier
 489         <replaceable>SYSLOG_IDENTIFIER</replaceable>.</para>
 490
 491         <para>This parameter can be specified multiple
 492         times.</para></listitem>
 493       </varlistentry>
 494
 495       <varlistentry>
 496         <term><option>-u</option></term>
 497         <term><option>--unit=<replaceable>UNIT</replaceable>|<replaceable>PATTERN</replaceable></option></term>
 498
 499         <listitem><para>Show messages for the specified systemd unit
 500         <replaceable>UNIT</replaceable> (such as a service unit), or
 501         for any of the units matched by
 502         <replaceable>PATTERN</replaceable>.  If a pattern is
 503         specified, a list of unit names found in the journal is
 504         compared with the specified pattern and all that match are
 505         used. For each unit name, a match is added for messages from
 506         the unit
 507         (<literal>_SYSTEMD_UNIT=<replaceable>UNIT</replaceable></literal>),
 508         along with additional matches for messages from systemd and
 509         messages about coredumps for the specified unit.</para>
 510
 511         <para>This parameter can be specified multiple times.</para>
 512         </listitem>
 513       </varlistentry>
 514
 515       <varlistentry>
 516         <term><option>--user-unit=</option></term>
 517
 518         <listitem><para>Show messages for the specified user session
 519         unit. This will add a match for messages from the unit
 520         (<literal>_SYSTEMD_USER_UNIT=</literal> and
 521         <literal>_UID=</literal>) and additional matches for messages
 522         from session systemd and messages about coredumps for the
 523         specified unit.</para>
 524
 525         <para>This parameter can be specified multiple times.</para>
 526         </listitem>
 527       </varlistentry>
 528
 529       <varlistentry>
 530         <term><option>-p</option></term>
 531         <term><option>--priority=</option></term>
 532
 533         <listitem><para>Filter output by message priorities or
 534         priority ranges. Takes either a single numeric or textual log
 535         level (i.e. between 0/<literal>emerg</literal> and
 536         7/<literal>debug</literal>), or a range of numeric/text log
 537         levels in the form FROM..TO. The log levels are the usual
 538         syslog log levels as documented in
 539         <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 540         i.e. <literal>emerg</literal> (0),
 541         <literal>alert</literal> (1), <literal>crit</literal> (2),
 542         <literal>err</literal> (3), <literal>warning</literal> (4),
 543         <literal>notice</literal> (5), <literal>info</literal> (6),
 544         <literal>debug</literal> (7). If a single log level is
 545         specified, all messages with this log level or a lower (hence
 546         more important) log level are shown. If a range is specified,
 547         all messages within the range are shown, including both the
 548         start and the end value of the range. This will add
 549         <literal>PRIORITY=</literal> matches for the specified
 550         priorities.</para></listitem>
 551       </varlistentry>
 552
 553       <varlistentry>
 554         <term><option>-c</option></term>
 555         <term><option>--cursor=</option></term>
 556
 557         <listitem><para>Start showing entries from the location in the
 558         journal specified by the passed cursor.</para></listitem>
 559       </varlistentry>
 560
 561       <varlistentry>
 562         <term><option>--after-cursor=</option></term>
 563
 564         <listitem><para>Start showing entries from the location in the
 565         journal <emphasis>after</emphasis> the location specified by
 566         the passed cursor.  The cursor is shown when the
 567         <option>--show-cursor</option> option is used.</para>
 568         </listitem>
 569       </varlistentry>
 570
 571       <varlistentry>
 572         <term><option>--show-cursor</option></term>
 573
 574         <listitem><para>The cursor is shown after the last entry after
 575         two dashes:</para>
 576         <programlisting>-- cursor: s=0639…</programlisting>
 577         <para>The format of the cursor is private
 578         and subject to change.</para></listitem>
 579       </varlistentry>
 580
 581       <varlistentry>
 582         <term><option>-S</option></term>
 583         <term><option>--since=</option></term>
 584         <term><option>-U</option></term>
 585         <term><option>--until=</option></term>
 586
 587         <listitem><para>Start showing entries on or newer than the specified date, or on or older than the specified
 588         date, respectively. Date specifications should be of the format <literal>2012-10-30 18:17:16</literal>.  If the
 589         time part is omitted, <literal>00:00:00</literal> is assumed.  If only the seconds component is omitted,
 590         <literal>:00</literal> is assumed. If the date component is omitted, the current day is assumed. Alternatively
 591         the strings <literal>yesterday</literal>, <literal>today</literal>, <literal>tomorrow</literal> are understood,
 592         which refer to 00:00:00 of the day before the current day, the current day, or the day after the current day,
 593         respectively. <literal>now</literal> refers to the current time. Finally, relative times may be specified,
 594         prefixed with <literal>-</literal> or <literal>+</literal>, referring to times before or after the current
 595         time, respectively. For complete time and date specification, see
 596         <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>. Note that
 597         <option>--output=short-full</option> prints timestamps that follow precisely this format.
 598         </para>
 599         </listitem>
 600       </varlistentry>
 601
 602       <varlistentry>
 603         <term><option>-F</option></term>
 604         <term><option>--field=</option></term>
 605
 606         <listitem><para>Print all possible data values the specified
 607         field can take in all entries of the journal.</para></listitem>
 608       </varlistentry>
 609
 610       <varlistentry>
 611         <term><option>-N</option></term>
 612         <term><option>--fields</option></term>
 613
 614         <listitem><para>Print all field names currently used in all entries of the journal.</para></listitem>
 615       </varlistentry>
 616
 617       <varlistentry>
 618         <term><option>--system</option></term>
 619         <term><option>--user</option></term>
 620
 621         <listitem><para>Show messages from system services and the
 622         kernel (with <option>--system</option>). Show messages from
 623         service of current user (with <option>--user</option>).  If
 624         neither is specified, show all messages that the user can see.
 625         </para></listitem>
 626       </varlistentry>
 627
 628       <varlistentry>
 629         <term><option>-M</option></term>
 630         <term><option>--machine=</option></term>
 631
 632         <listitem><para>Show messages from a running, local
 633         container. Specify a container name to connect to.</para>
 634         </listitem>
 635       </varlistentry>
 636
 637       <varlistentry>
 638         <term><option>-D <replaceable>DIR</replaceable></option></term>
 639         <term><option>--directory=<replaceable>DIR</replaceable></option></term>
 640
 641         <listitem><para>Takes a directory path as argument. If
 642         specified, journalctl will operate on the specified journal
 643         directory <replaceable>DIR</replaceable> instead of the
 644         default runtime and system journal paths.</para></listitem>
 645       </varlistentry>
 646
 647       <varlistentry>
 648         <term><option>--file=<replaceable>GLOB</replaceable></option></term>
 649
 650         <listitem><para>Takes a file glob as an argument. If
 651         specified, journalctl will operate on the specified journal
 652         files matching <replaceable>GLOB</replaceable> instead of the
 653         default runtime and system journal paths. May be specified
 654         multiple times, in which case files will be suitably
 655         interleaved.</para></listitem>
 656       </varlistentry>
 657
 658       <varlistentry>
 659         <term><option>--root=<replaceable>ROOT</replaceable></option></term>
 660
 661         <listitem><para>Takes a directory path as an argument. If
 662         specified, journalctl will operate on journal directories and catalog file hierarchy
 663         underneath the specified directory instead of the root
 664         directory (e.g. <option>--update-catalog</option> will create
 665         <filename><replaceable>ROOT</replaceable>/var/lib/systemd/catalog/database</filename>,
 666         and journal files under <filename><replaceable>ROOT</replaceable>/run/journal</filename>
 667         or <filename><replaceable>ROOT</replaceable>/var/log/journal</filename> will be displayed).
 668         </para></listitem>
 669       </varlistentry>
 670
 671       <varlistentry>
 672         <term><option>--new-id128</option></term>
 673
 674         <listitem><para>Instead of showing journal contents, generate
 675         a new 128-bit ID suitable for identifying messages. This is
 676         intended for usage by developers who need a new identifier for
 677         a new message they introduce and want to make
 678         recognizable. This will print the new ID in three different
 679         formats which can be copied into source code or similar.
 680         </para></listitem>
 681       </varlistentry>
 682
 683       <varlistentry>
 684         <term><option>--header</option></term>
 685
 686         <listitem><para>Instead of showing journal contents, show
 687         internal header information of the journal fields
 688         accessed.</para></listitem>
 689       </varlistentry>
 690
 691       <varlistentry>
 692         <term><option>--disk-usage</option></term>
 693
 694         <listitem><para>Shows the current disk usage of all journal
 695         files. This shows the sum of the disk usage of all archived
 696         and active journal files.</para></listitem>
 697       </varlistentry>
 698
 699       <varlistentry>
 700         <term><option>--vacuum-size=</option></term>
 701         <term><option>--vacuum-time=</option></term>
 702         <term><option>--vacuum-files=</option></term>
 703
 704         <listitem><para>Removes archived journal files until the disk
 705         space they use falls below the specified size (specified with
 706         the usual <literal>K</literal>, <literal>M</literal>,
 707         <literal>G</literal> and <literal>T</literal> suffixes), or all
 708         archived journal files contain no data older than the specified
 709         timespan (specified with the usual <literal>s</literal>,
 710         <literal>m</literal>, <literal>h</literal>,
 711         <literal>days</literal>, <literal>months</literal>,
 712         <literal>weeks</literal> and <literal>years</literal> suffixes),
 713         or no more than the specified number of separate journal files
 714         remain. Note that running <option>--vacuum-size=</option> has
 715         only an indirect effect on the output shown by
 716         <option>--disk-usage</option>, as the latter includes active
 717         journal files, while the vacuuming operation only operates
 718         on archived journal files. Similarly,
 719         <option>--vacuum-files=</option> might not actually reduce the
 720         number of journal files to below the specified number, as it
 721         will not remove active journal
 722         files. <option>--vacuum-size=</option>,
 723         <option>--vacuum-time=</option> and
 724         <option>--vacuum-files=</option> may be combined in a single
 725         invocation to enforce any combination of a size, a time and a
 726         number of files limit on the archived journal
 727         files. Specifying any of these three parameters as zero is
 728         equivalent to not enforcing the specific limit, and is thus
 729         redundant.</para></listitem>
 730       </varlistentry>
 731
 732       <varlistentry>
 733         <term><option>--list-catalog
 734         <optional><replaceable>128-bit-ID…</replaceable></optional>
 735         </option></term>
 736
 737         <listitem><para>List the contents of the message catalog as a
 738         table of message IDs, plus their short description strings.
 739         </para>
 740
 741         <para>If any <replaceable>128-bit-ID</replaceable>s are
 742         specified, only those entries are shown.</para>
 743         </listitem>
 744       </varlistentry>
 745
 746       <varlistentry>
 747         <term><option>--dump-catalog
 748         <optional><replaceable>128-bit-ID…</replaceable></optional>
 749         </option></term>
 750
 751         <listitem><para>Show the contents of the message catalog, with
 752         entries separated by a line consisting of two dashes and the
 753         ID (the format is the same as <filename>.catalog</filename>
 754         files).</para>
 755
 756         <para>If any <replaceable>128-bit-ID</replaceable>s are
 757         specified, only those entries are shown.</para>
 758         </listitem>
 759       </varlistentry>
 760
 761       <varlistentry>
 762         <term><option>--update-catalog</option></term>
 763
 764         <listitem><para>Update the message catalog index. This command
 765         needs to be executed each time new catalog files are
 766         installed, removed, or updated to rebuild the binary catalog
 767         index.</para></listitem>
 768       </varlistentry>
 769
 770       <varlistentry>
 771         <term><option>--setup-keys</option></term>
 772
 773         <listitem><para>Instead of showing journal contents, generate
 774         a new key pair for Forward Secure Sealing (FSS). This will
 775         generate a sealing key and a verification key. The sealing key
 776         is stored in the journal data directory and shall remain on
 777         the host. The verification key should be stored
 778         externally. Refer to the <option>Seal=</option> option in
 779         <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 780         for information on Forward Secure Sealing and for a link to a
 781         refereed scholarly paper detailing the cryptographic theory it
 782         is based on.</para></listitem>
 783       </varlistentry>
 784
 785       <varlistentry>
 786         <term><option>--force</option></term>
 787
 788         <listitem><para>When <option>--setup-keys</option> is passed
 789         and Forward Secure Sealing (FSS) has already been configured,
 790         recreate FSS keys.</para></listitem>
 791       </varlistentry>
 792
 793       <varlistentry>
 794         <term><option>--interval=</option></term>
 795
 796         <listitem><para>Specifies the change interval for the sealing
 797         key when generating an FSS key pair with
 798         <option>--setup-keys</option>. Shorter intervals increase CPU
 799         consumption but shorten the time range of undetectable journal
 800         alterations. Defaults to 15min.</para></listitem>
 801       </varlistentry>
 802
 803       <varlistentry>
 804         <term><option>--verify</option></term>
 805
 806         <listitem><para>Check the journal file for internal
 807         consistency. If the file has been generated with FSS enabled and
 808         the FSS verification key has been specified with
 809         <option>--verify-key=</option>, authenticity of the journal file
 810         is verified.</para></listitem>
 811       </varlistentry>
 812
 813       <varlistentry>
 814         <term><option>--verify-key=</option></term>
 815
 816         <listitem><para>Specifies the FSS verification key to use for
 817         the <option>--verify</option> operation.</para></listitem>
 818       </varlistentry>
 819
 820       <varlistentry>
 821         <term><option>--sync</option></term>
 822
 823         <listitem><para>Asks the journal daemon to write all yet
 824         unwritten journal data to the backing file system and
 825         synchronize all journals. This call does not return until the
 826         synchronization operation is complete. This command guarantees
 827         that any log messages written before its invocation are safely
 828         stored on disk at the time it returns.</para></listitem>
 829       </varlistentry>
 830
 831       <varlistentry>
 832         <term><option>--flush</option></term>
 833
 834         <listitem><para>Asks the journal daemon to flush any log data
 835         stored in <filename>/run/log/journal</filename> into
 836         <filename>/var/log/journal</filename>, if persistent storage
 837         is enabled. This call does not return until the operation is
 838         complete. Note that this call is idempotent: the data is only
 839         flushed from <filename>/run/log/journal</filename> into
 840         <filename>/var/log/journal</filename> once during system
 841         runtime, and this command exits cleanly without executing any
 842         operation if this has already happened. This command
 843         effectively guarantees that all data is flushed to
 844         <filename>/var/log/journal</filename> at the time it
 845         returns.</para></listitem>
 846       </varlistentry>
 847
 848       <varlistentry>
 849         <term><option>--rotate</option></term>
 850
 851         <listitem><para>Asks the journal daemon to rotate journal
 852         files. This call does not return until the rotation operation
 853         is complete.</para></listitem>
 854       </varlistentry>
 855
 856       <xi:include href="standard-options.xml" xpointer="help" />
 857       <xi:include href="standard-options.xml" xpointer="version" />
 858       <xi:include href="standard-options.xml" xpointer="no-pager" />
 859     </variablelist>
 860   </refsect1>
 861
 862   <refsect1>
 863     <title>Exit status</title>
 864
 865     <para>On success, 0 is returned; otherwise, a non-zero failure
 866     code is returned.</para>
 867   </refsect1>
 868
 869   <xi:include href="less-variables.xml" />
 870
 871   <refsect1>
 872     <title>Examples</title>
 873
 874     <para>Without arguments, all collected logs are shown
 875     unfiltered:</para>
 876
 877     <programlisting>journalctl</programlisting>
 878
 879     <para>With one match specified, all entries with a field matching
 880     the expression are shown:</para>
 881
 882     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service</programlisting>
 883
 884     <para>If two different fields are matched, only entries matching
 885     both expressions at the same time are shown:</para>
 886
 887     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097</programlisting>
 888
 889     <para>If two matches refer to the same field, all entries matching
 890     either expression are shown:</para>
 891
 892     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _SYSTEMD_UNIT=dbus.service</programlisting>
 893
 894     <para>If the separator <literal>+</literal> is used, two
 895     expressions may be combined in a logical OR. The following will
 896     show all messages from the Avahi service process with the PID
 897     28097 plus all messages from the D-Bus service (from any of its
 898     processes):</para>
 899
 900     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097 + _SYSTEMD_UNIT=dbus.service</programlisting>
 901
 902     <para>Show all logs generated by the D-Bus executable:</para>
 903
 904     <programlisting>journalctl /usr/bin/dbus-daemon</programlisting>
 905
 906     <para>Show all kernel logs from previous boot:</para>
 907
 908     <programlisting>journalctl -k -b -1</programlisting>
 909
 910     <para>Show a live log display from a system service
 911     <filename>apache.service</filename>:</para>
 912
 913     <programlisting>journalctl -f -u apache</programlisting>
 914
 915   </refsect1>
 916
 917   <refsect1>
 918     <title>See Also</title>
 919     <para>
 920       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 921       <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 922       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 923       <citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 924       <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 925       <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 926       <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 927     </para>
 928   </refsect1>
 929 </refentry>