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). To import the binary stream back
 323                 into native journald format use
 324                 <citerefentry><refentrytitle>systemd-journal-remote</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 325               </listitem>
 326             </varlistentry>
 327
 328             <varlistentry>
 329               <term>
 330                 <option>json</option>
 331               </term>
 332               <listitem>
 333                 <para>formats entries as JSON data structures, one per
 334                 line (see
 335                 <ulink url="http://www.freedesktop.org/wiki/Software/systemd/json">Journal JSON Format</ulink>
 336                 for more information).</para>
 337               </listitem>
 338             </varlistentry>
 339
 340             <varlistentry>
 341               <term>
 342                 <option>json-pretty</option>
 343               </term>
 344               <listitem>
 345                 <para>formats entries as JSON data structures, but
 346                 formats them in multiple lines in order to make them
 347                 more readable by humans.</para>
 348               </listitem>
 349             </varlistentry>
 350
 351             <varlistentry>
 352               <term>
 353                 <option>json-sse</option>
 354               </term>
 355               <listitem>
 356                 <para>formats entries as JSON data structures, but wraps
 357                 them in a format suitable for
 358                 <ulink url="https://developer.mozilla.org/en-US/docs/Server-sent_events/Using_server-sent_events">Server-Sent Events</ulink>.
 359                 </para>
 360               </listitem>
 361             </varlistentry>
 362
 363             <varlistentry>
 364               <term>
 365                 <option>cat</option>
 366               </term>
 367               <listitem>
 368                 <para>generates a very terse output, only showing the
 369                 actual message of each journal entry with no metadata,
 370                 not even a timestamp.</para>
 371               </listitem>
 372             </varlistentry>
 373           </variablelist>
 374         </listitem>
 375       </varlistentry>
 376
 377       <varlistentry>
 378         <term><option>--utc</option></term>
 379
 380         <listitem><para>Express time in Coordinated Universal Time
 381         (UTC).</para></listitem>
 382       </varlistentry>
 383
 384       <varlistentry>
 385         <term><option>--no-hostname</option></term>
 386
 387         <listitem><para>Don't show the hostname field of log messages originating from the local host. This switch only
 388         has an effect on the <option>short</option> family of output modes (see above).</para></listitem>
 389       </varlistentry>
 390
 391       <varlistentry>
 392         <term><option>-x</option></term>
 393         <term><option>--catalog</option></term>
 394
 395         <listitem><para>Augment log lines with explanation texts from
 396         the message catalog. This will add explanatory help texts to
 397         log messages in the output where this is available. These
 398         short help texts will explain the context of an error or log
 399         event, possible solutions, as well as pointers to support
 400         forums, developer documentation, and any other relevant
 401         manuals. Note that help texts are not available for all
 402         messages, but only for selected ones. For more information on
 403         the message catalog, please refer to the
 404         <ulink url="http://www.freedesktop.org/wiki/Software/systemd/catalog">Message Catalog Developer Documentation</ulink>.</para>
 405
 406         <para>Note: when attaching <command>journalctl</command>
 407         output to bug reports, please do <emphasis>not</emphasis> use
 408         <option>-x</option>.</para>
 409         </listitem>
 410       </varlistentry>
 411
 412       <varlistentry>
 413         <term><option>-q</option></term>
 414         <term><option>--quiet</option></term>
 415
 416         <listitem><para>Suppresses all info messages
 417         (i.e. "-- Logs begin at …", "-- Reboot --"),
 418         any warning messages regarding
 419         inaccessible system journals when run as a normal
 420         user.</para></listitem>
 421       </varlistentry>
 422
 423       <varlistentry>
 424         <term><option>-m</option></term>
 425         <term><option>--merge</option></term>
 426
 427         <listitem><para>Show entries interleaved from all available
 428         journals, including remote ones.</para></listitem>
 429       </varlistentry>
 430
 431       <varlistentry>
 432         <term><option>-b <optional><replaceable>ID</replaceable></optional><optional><replaceable>±offset</replaceable></optional></option></term>
 433         <term><option>--boot=<optional><replaceable>ID</replaceable></optional><optional><replaceable>±offset</replaceable></optional></option></term>
 434
 435         <listitem><para>Show messages from a specific boot. This will
 436         add a match for <literal>_BOOT_ID=</literal>.</para>
 437
 438         <para>The argument may be empty, in which case logs for the
 439         current boot will be shown.</para>
 440
 441         <para>If the boot ID is omitted, a positive
 442         <replaceable>offset</replaceable> will look up the boots
 443         starting from the beginning of the journal, and an
 444         equal-or-less-than zero <replaceable>offset</replaceable> will
 445         look up boots starting from the end of the journal. Thus,
 446         <constant>1</constant> means the first boot found in the
 447         journal in chronological order, <constant>2</constant> the
 448         second and so on; while <constant>-0</constant> is the last
 449         boot, <constant>-1</constant> the boot before last, and so
 450         on. An empty <replaceable>offset</replaceable> is equivalent
 451         to specifying <constant>-0</constant>, except when the current
 452         boot is not the last boot (e.g. because
 453         <option>--directory</option> was specified to look at logs
 454         from a different machine).</para>
 455
 456         <para>If the 32-character <replaceable>ID</replaceable> is
 457         specified, it may optionally be followed by
 458         <replaceable>offset</replaceable> which identifies the boot
 459         relative to the one given by boot
 460         <replaceable>ID</replaceable>. Negative values mean earlier
 461         boots and positive values mean later boots. If
 462         <replaceable>offset</replaceable> is not specified, a value of
 463         zero is assumed, and the logs for the boot given by
 464         <replaceable>ID</replaceable> are shown.</para>
 465         </listitem>
 466       </varlistentry>
 467
 468       <varlistentry>
 469         <term><option>--list-boots</option></term>
 470
 471         <listitem><para>Show a tabular list of boot numbers (relative to
 472         the current boot), their IDs, and the timestamps of the first
 473         and last message pertaining to the boot.</para></listitem>
 474       </varlistentry>
 475
 476       <varlistentry>
 477         <term><option>-k</option></term>
 478         <term><option>--dmesg</option></term>
 479
 480         <listitem><para>Show only kernel messages. This implies
 481         <option>-b</option> and adds the match
 482         <literal>_TRANSPORT=kernel</literal>.</para></listitem>
 483       </varlistentry>
 484
 485       <varlistentry>
 486         <term><option>-t</option></term>
 487         <term><option>--identifier=<replaceable>SYSLOG_IDENTIFIER</replaceable></option></term>
 488
 489         <listitem><para>Show messages for the specified syslog
 490         identifier
 491         <replaceable>SYSLOG_IDENTIFIER</replaceable>.</para>
 492
 493         <para>This parameter can be specified multiple
 494         times.</para></listitem>
 495       </varlistentry>
 496
 497       <varlistentry>
 498         <term><option>-u</option></term>
 499         <term><option>--unit=<replaceable>UNIT</replaceable>|<replaceable>PATTERN</replaceable></option></term>
 500
 501         <listitem><para>Show messages for the specified systemd unit
 502         <replaceable>UNIT</replaceable> (such as a service unit), or
 503         for any of the units matched by
 504         <replaceable>PATTERN</replaceable>.  If a pattern is
 505         specified, a list of unit names found in the journal is
 506         compared with the specified pattern and all that match are
 507         used. For each unit name, a match is added for messages from
 508         the unit
 509         (<literal>_SYSTEMD_UNIT=<replaceable>UNIT</replaceable></literal>),
 510         along with additional matches for messages from systemd and
 511         messages about coredumps for the specified unit.</para>
 512
 513         <para>This parameter can be specified multiple times.</para>
 514         </listitem>
 515       </varlistentry>
 516
 517       <varlistentry>
 518         <term><option>--user-unit=</option></term>
 519
 520         <listitem><para>Show messages for the specified user session
 521         unit. This will add a match for messages from the unit
 522         (<literal>_SYSTEMD_USER_UNIT=</literal> and
 523         <literal>_UID=</literal>) and additional matches for messages
 524         from session systemd and messages about coredumps for the
 525         specified unit.</para>
 526
 527         <para>This parameter can be specified multiple times.</para>
 528         </listitem>
 529       </varlistentry>
 530
 531       <varlistentry>
 532         <term><option>-p</option></term>
 533         <term><option>--priority=</option></term>
 534
 535         <listitem><para>Filter output by message priorities or
 536         priority ranges. Takes either a single numeric or textual log
 537         level (i.e. between 0/<literal>emerg</literal> and
 538         7/<literal>debug</literal>), or a range of numeric/text log
 539         levels in the form FROM..TO. The log levels are the usual
 540         syslog log levels as documented in
 541         <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 542         i.e. <literal>emerg</literal> (0),
 543         <literal>alert</literal> (1), <literal>crit</literal> (2),
 544         <literal>err</literal> (3), <literal>warning</literal> (4),
 545         <literal>notice</literal> (5), <literal>info</literal> (6),
 546         <literal>debug</literal> (7). If a single log level is
 547         specified, all messages with this log level or a lower (hence
 548         more important) log level are shown. If a range is specified,
 549         all messages within the range are shown, including both the
 550         start and the end value of the range. This will add
 551         <literal>PRIORITY=</literal> matches for the specified
 552         priorities.</para></listitem>
 553       </varlistentry>
 554
 555       <varlistentry>
 556         <term><option>-c</option></term>
 557         <term><option>--cursor=</option></term>
 558
 559         <listitem><para>Start showing entries from the location in the
 560         journal specified by the passed cursor.</para></listitem>
 561       </varlistentry>
 562
 563       <varlistentry>
 564         <term><option>--after-cursor=</option></term>
 565
 566         <listitem><para>Start showing entries from the location in the
 567         journal <emphasis>after</emphasis> the location specified by
 568         the passed cursor.  The cursor is shown when the
 569         <option>--show-cursor</option> option is used.</para>
 570         </listitem>
 571       </varlistentry>
 572
 573       <varlistentry>
 574         <term><option>--show-cursor</option></term>
 575
 576         <listitem><para>The cursor is shown after the last entry after
 577         two dashes:</para>
 578         <programlisting>-- cursor: s=0639…</programlisting>
 579         <para>The format of the cursor is private
 580         and subject to change.</para></listitem>
 581       </varlistentry>
 582
 583       <varlistentry>
 584         <term><option>-S</option></term>
 585         <term><option>--since=</option></term>
 586         <term><option>-U</option></term>
 587         <term><option>--until=</option></term>
 588
 589         <listitem><para>Start showing entries on or newer than the specified date, or on or older than the specified
 590         date, respectively. Date specifications should be of the format <literal>2012-10-30 18:17:16</literal>.  If the
 591         time part is omitted, <literal>00:00:00</literal> is assumed.  If only the seconds component is omitted,
 592         <literal>:00</literal> is assumed. If the date component is omitted, the current day is assumed. Alternatively
 593         the strings <literal>yesterday</literal>, <literal>today</literal>, <literal>tomorrow</literal> are understood,
 594         which refer to 00:00:00 of the day before the current day, the current day, or the day after the current day,
 595         respectively. <literal>now</literal> refers to the current time. Finally, relative times may be specified,
 596         prefixed with <literal>-</literal> or <literal>+</literal>, referring to times before or after the current
 597         time, respectively. For complete time and date specification, see
 598         <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>. Note that
 599         <option>--output=short-full</option> prints timestamps that follow precisely this format.
 600         </para>
 601         </listitem>
 602       </varlistentry>
 603
 604       <varlistentry>
 605         <term><option>-F</option></term>
 606         <term><option>--field=</option></term>
 607
 608         <listitem><para>Print all possible data values the specified
 609         field can take in all entries of the journal.</para></listitem>
 610       </varlistentry>
 611
 612       <varlistentry>
 613         <term><option>-N</option></term>
 614         <term><option>--fields</option></term>
 615
 616         <listitem><para>Print all field names currently used in all entries of the journal.</para></listitem>
 617       </varlistentry>
 618
 619       <varlistentry>
 620         <term><option>--system</option></term>
 621         <term><option>--user</option></term>
 622
 623         <listitem><para>Show messages from system services and the
 624         kernel (with <option>--system</option>). Show messages from
 625         service of current user (with <option>--user</option>).  If
 626         neither is specified, show all messages that the user can see.
 627         </para></listitem>
 628       </varlistentry>
 629
 630       <varlistentry>
 631         <term><option>-M</option></term>
 632         <term><option>--machine=</option></term>
 633
 634         <listitem><para>Show messages from a running, local
 635         container. Specify a container name to connect to.</para>
 636         </listitem>
 637       </varlistentry>
 638
 639       <varlistentry>
 640         <term><option>-D <replaceable>DIR</replaceable></option></term>
 641         <term><option>--directory=<replaceable>DIR</replaceable></option></term>
 642
 643         <listitem><para>Takes a directory path as argument. If
 644         specified, journalctl will operate on the specified journal
 645         directory <replaceable>DIR</replaceable> instead of the
 646         default runtime and system journal paths.</para></listitem>
 647       </varlistentry>
 648
 649       <varlistentry>
 650         <term><option>--file=<replaceable>GLOB</replaceable></option></term>
 651
 652         <listitem><para>Takes a file glob as an argument. If
 653         specified, journalctl will operate on the specified journal
 654         files matching <replaceable>GLOB</replaceable> instead of the
 655         default runtime and system journal paths. May be specified
 656         multiple times, in which case files will be suitably
 657         interleaved.</para></listitem>
 658       </varlistentry>
 659
 660       <varlistentry>
 661         <term><option>--root=<replaceable>ROOT</replaceable></option></term>
 662
 663         <listitem><para>Takes a directory path as an argument. If
 664         specified, journalctl will operate on journal directories and catalog file hierarchy
 665         underneath the specified directory instead of the root
 666         directory (e.g. <option>--update-catalog</option> will create
 667         <filename><replaceable>ROOT</replaceable>/var/lib/systemd/catalog/database</filename>,
 668         and journal files under <filename><replaceable>ROOT</replaceable>/run/journal</filename>
 669         or <filename><replaceable>ROOT</replaceable>/var/log/journal</filename> will be displayed).
 670         </para></listitem>
 671       </varlistentry>
 672
 673       <varlistentry>
 674         <term><option>--new-id128</option></term>
 675
 676         <listitem><para>Instead of showing journal contents, generate
 677         a new 128-bit ID suitable for identifying messages. This is
 678         intended for usage by developers who need a new identifier for
 679         a new message they introduce and want to make
 680         recognizable. This will print the new ID in three different
 681         formats which can be copied into source code or similar.
 682         </para></listitem>
 683       </varlistentry>
 684
 685       <varlistentry>
 686         <term><option>--header</option></term>
 687
 688         <listitem><para>Instead of showing journal contents, show
 689         internal header information of the journal fields
 690         accessed.</para></listitem>
 691       </varlistentry>
 692
 693       <varlistentry>
 694         <term><option>--disk-usage</option></term>
 695
 696         <listitem><para>Shows the current disk usage of all journal
 697         files. This shows the sum of the disk usage of all archived
 698         and active journal files.</para></listitem>
 699       </varlistentry>
 700
 701       <varlistentry>
 702         <term><option>--vacuum-size=</option></term>
 703         <term><option>--vacuum-time=</option></term>
 704         <term><option>--vacuum-files=</option></term>
 705
 706         <listitem><para>Removes archived journal files until the disk
 707         space they use falls below the specified size (specified with
 708         the usual <literal>K</literal>, <literal>M</literal>,
 709         <literal>G</literal> and <literal>T</literal> suffixes), or all
 710         archived journal files contain no data older than the specified
 711         timespan (specified with the usual <literal>s</literal>,
 712         <literal>m</literal>, <literal>h</literal>,
 713         <literal>days</literal>, <literal>months</literal>,
 714         <literal>weeks</literal> and <literal>years</literal> suffixes),
 715         or no more than the specified number of separate journal files
 716         remain. Note that running <option>--vacuum-size=</option> has
 717         only an indirect effect on the output shown by
 718         <option>--disk-usage</option>, as the latter includes active
 719         journal files, while the vacuuming operation only operates
 720         on archived journal files. Similarly,
 721         <option>--vacuum-files=</option> might not actually reduce the
 722         number of journal files to below the specified number, as it
 723         will not remove active journal
 724         files. <option>--vacuum-size=</option>,
 725         <option>--vacuum-time=</option> and
 726         <option>--vacuum-files=</option> may be combined in a single
 727         invocation to enforce any combination of a size, a time and a
 728         number of files limit on the archived journal
 729         files. Specifying any of these three parameters as zero is
 730         equivalent to not enforcing the specific limit, and is thus
 731         redundant.</para></listitem>
 732       </varlistentry>
 733
 734       <varlistentry>
 735         <term><option>--list-catalog
 736         <optional><replaceable>128-bit-ID…</replaceable></optional>
 737         </option></term>
 738
 739         <listitem><para>List the contents of the message catalog as a
 740         table of message IDs, plus their short description strings.
 741         </para>
 742
 743         <para>If any <replaceable>128-bit-ID</replaceable>s are
 744         specified, only those entries are shown.</para>
 745         </listitem>
 746       </varlistentry>
 747
 748       <varlistentry>
 749         <term><option>--dump-catalog
 750         <optional><replaceable>128-bit-ID…</replaceable></optional>
 751         </option></term>
 752
 753         <listitem><para>Show the contents of the message catalog, with
 754         entries separated by a line consisting of two dashes and the
 755         ID (the format is the same as <filename>.catalog</filename>
 756         files).</para>
 757
 758         <para>If any <replaceable>128-bit-ID</replaceable>s are
 759         specified, only those entries are shown.</para>
 760         </listitem>
 761       </varlistentry>
 762
 763       <varlistentry>
 764         <term><option>--update-catalog</option></term>
 765
 766         <listitem><para>Update the message catalog index. This command
 767         needs to be executed each time new catalog files are
 768         installed, removed, or updated to rebuild the binary catalog
 769         index.</para></listitem>
 770       </varlistentry>
 771
 772       <varlistentry>
 773         <term><option>--setup-keys</option></term>
 774
 775         <listitem><para>Instead of showing journal contents, generate
 776         a new key pair for Forward Secure Sealing (FSS). This will
 777         generate a sealing key and a verification key. The sealing key
 778         is stored in the journal data directory and shall remain on
 779         the host. The verification key should be stored
 780         externally. Refer to the <option>Seal=</option> option in
 781         <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 782         for information on Forward Secure Sealing and for a link to a
 783         refereed scholarly paper detailing the cryptographic theory it
 784         is based on.</para></listitem>
 785       </varlistentry>
 786
 787       <varlistentry>
 788         <term><option>--force</option></term>
 789
 790         <listitem><para>When <option>--setup-keys</option> is passed
 791         and Forward Secure Sealing (FSS) has already been configured,
 792         recreate FSS keys.</para></listitem>
 793       </varlistentry>
 794
 795       <varlistentry>
 796         <term><option>--interval=</option></term>
 797
 798         <listitem><para>Specifies the change interval for the sealing
 799         key when generating an FSS key pair with
 800         <option>--setup-keys</option>. Shorter intervals increase CPU
 801         consumption but shorten the time range of undetectable journal
 802         alterations. Defaults to 15min.</para></listitem>
 803       </varlistentry>
 804
 805       <varlistentry>
 806         <term><option>--verify</option></term>
 807
 808         <listitem><para>Check the journal file for internal
 809         consistency. If the file has been generated with FSS enabled and
 810         the FSS verification key has been specified with
 811         <option>--verify-key=</option>, authenticity of the journal file
 812         is verified.</para></listitem>
 813       </varlistentry>
 814
 815       <varlistentry>
 816         <term><option>--verify-key=</option></term>
 817
 818         <listitem><para>Specifies the FSS verification key to use for
 819         the <option>--verify</option> operation.</para></listitem>
 820       </varlistentry>
 821
 822       <varlistentry>
 823         <term><option>--sync</option></term>
 824
 825         <listitem><para>Asks the journal daemon to write all yet
 826         unwritten journal data to the backing file system and
 827         synchronize all journals. This call does not return until the
 828         synchronization operation is complete. This command guarantees
 829         that any log messages written before its invocation are safely
 830         stored on disk at the time it returns.</para></listitem>
 831       </varlistentry>
 832
 833       <varlistentry>
 834         <term><option>--flush</option></term>
 835
 836         <listitem><para>Asks the journal daemon to flush any log data
 837         stored in <filename>/run/log/journal</filename> into
 838         <filename>/var/log/journal</filename>, if persistent storage
 839         is enabled. This call does not return until the operation is
 840         complete. Note that this call is idempotent: the data is only
 841         flushed from <filename>/run/log/journal</filename> into
 842         <filename>/var/log/journal</filename> once during system
 843         runtime, and this command exits cleanly without executing any
 844         operation if this has already happened. This command
 845         effectively guarantees that all data is flushed to
 846         <filename>/var/log/journal</filename> at the time it
 847         returns.</para></listitem>
 848       </varlistentry>
 849
 850       <varlistentry>
 851         <term><option>--rotate</option></term>
 852
 853         <listitem><para>Asks the journal daemon to rotate journal
 854         files. This call does not return until the rotation operation
 855         is complete.</para></listitem>
 856       </varlistentry>
 857
 858       <xi:include href="standard-options.xml" xpointer="help" />
 859       <xi:include href="standard-options.xml" xpointer="version" />
 860       <xi:include href="standard-options.xml" xpointer="no-pager" />
 861     </variablelist>
 862   </refsect1>
 863
 864   <refsect1>
 865     <title>Exit status</title>
 866
 867     <para>On success, 0 is returned; otherwise, a non-zero failure
 868     code is returned.</para>
 869   </refsect1>
 870
 871   <xi:include href="less-variables.xml" />
 872
 873   <refsect1>
 874     <title>Examples</title>
 875
 876     <para>Without arguments, all collected logs are shown
 877     unfiltered:</para>
 878
 879     <programlisting>journalctl</programlisting>
 880
 881     <para>With one match specified, all entries with a field matching
 882     the expression are shown:</para>
 883
 884     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service</programlisting>
 885
 886     <para>If two different fields are matched, only entries matching
 887     both expressions at the same time are shown:</para>
 888
 889     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097</programlisting>
 890
 891     <para>If two matches refer to the same field, all entries matching
 892     either expression are shown:</para>
 893
 894     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _SYSTEMD_UNIT=dbus.service</programlisting>
 895
 896     <para>If the separator <literal>+</literal> is used, two
 897     expressions may be combined in a logical OR. The following will
 898     show all messages from the Avahi service process with the PID
 899     28097 plus all messages from the D-Bus service (from any of its
 900     processes):</para>
 901
 902     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097 + _SYSTEMD_UNIT=dbus.service</programlisting>
 903
 904     <para>Show all logs generated by the D-Bus executable:</para>
 905
 906     <programlisting>journalctl /usr/bin/dbus-daemon</programlisting>
 907
 908     <para>Show all kernel logs from previous boot:</para>
 909
 910     <programlisting>journalctl -k -b -1</programlisting>
 911
 912     <para>Show a live log display from a system service
 913     <filename>apache.service</filename>:</para>
 914
 915     <programlisting>journalctl -f -u apache</programlisting>
 916
 917   </refsect1>
 918
 919   <refsect1>
 920     <title>See Also</title>
 921     <para>
 922       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 923       <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 924       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 925       <citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 926       <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 927       <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 928       <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 929       <citerefentry><refentrytitle>systemd-journal-remote</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 930       <citerefentry><refentrytitle>systemd-journal-upload</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 931     </para>
 932   </refsect1>
 933 </refentry>