man/journalctl.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
   5
   6 <refentry id="journalctl"
   7           xmlns:xi="http://www.w3.org/2001/XInclude">
   8
   9   <refentryinfo>
  10     <title>journalctl</title>
  11     <productname>systemd</productname>
  12   </refentryinfo>
  13
  14   <refmeta>
  15     <refentrytitle>journalctl</refentrytitle>
  16     <manvolnum>1</manvolnum>
  17   </refmeta>
  18
  19   <refnamediv>
  20     <refname>journalctl</refname>
  21     <refpurpose>Query the systemd journal</refpurpose>
  22   </refnamediv>
  23
  24   <refsynopsisdiv>
  25     <cmdsynopsis>
  26       <command>journalctl</command>
  27       <arg choice="opt" rep="repeat">OPTIONS</arg>
  28       <arg choice="opt" rep="repeat">MATCHES</arg>
  29     </cmdsynopsis>
  30   </refsynopsisdiv>
  31
  32   <refsect1>
  33     <title>Description</title>
  34
  35     <para><command>journalctl</command> may be used to query the contents of the
  36     <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> journal as
  37     written by
  38     <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
  39
  40     <para>If called without parameters, it will show the full contents of the journal, starting with the
  41     oldest entry collected.</para>
  42
  43     <para>If one or more match arguments are passed, the output is filtered accordingly. A match is in the
  44     format <literal>FIELD=VALUE</literal>, e.g. <literal>_SYSTEMD_UNIT=httpd.service</literal>, referring to
  45     the components of a structured journal entry. See
  46     <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
  47     for a list of well-known fields. If multiple matches are specified matching different fields, the log
  48     entries are filtered by both, i.e. the resulting output will show only entries matching all the specified
  49     matches of this kind. If two matches apply to the same field, then they are automatically matched as
  50     alternatives, i.e. the resulting output will show entries matching any of the specified matches for the
  51     same field. Finally, the character <literal>+</literal> may appear as a separate word between other terms
  52     on the command line. This causes all matches before and after to be combined in a disjunction
  53     (i.e. logical OR).</para>
  54
  55     <para>It is also possible to filter the entries by specifying an absolute file path as an argument. The
  56     file path may be a file or a symbolic link and the file must exist at the time of the query. If a file
  57     path refers to an executable binary, an <literal>_EXE=</literal> match for the canonicalized binary path
  58     is added to the query. If a file path refers to an executable script, a <literal>_COMM=</literal> match
  59     for the script name is added to the query. If a file path refers to a device node,
  60     <literal>_KERNEL_DEVICE=</literal> matches for the kernel name of the device and for each of its ancestor
  61     devices is added to the query. Symbolic links are dereferenced, kernel names are synthesized, and parent
  62     devices are identified from the environment at the time of the query. In general, a device node is the
  63     best proxy for an actual device, as log entries do not usually contain fields that identify an actual
  64     device. For the resulting log entries to be correct for the actual device, the relevant parts of the
  65     environment at the time the entry was logged, in particular the actual device corresponding to the device
  66     node, must have been the same as those at the time of the query. Because device nodes generally change
  67     their corresponding devices across reboots, specifying a device node path causes the resulting entries to
  68     be restricted to those from the current boot.</para>
  69
  70     <para>Additional constraints may be added using options <option>--boot</option>,
  71     <option>--unit=</option>, etc., to further limit what entries will be shown (logical AND).</para>
  72
  73     <para>Output is interleaved from all accessible journal files, whether they are rotated or currently
  74     being written, and regardless of whether they belong to the system itself or are accessible user
  75     journals. The <option>--header</option> option can be used to identify which files
  76     <emphasis>are</emphasis> being shown.</para>
  77
  78     <para>The set of journal files which will be used can be modified using the <option>--user</option>,
  79     <option>--system</option>, <option>--directory</option>, and <option>--file</option> options, see
  80     below.</para>
  81
  82     <para>All users are granted access to their private per-user journals. However, by default, only root and
  83     users who are members of a few special groups are granted access to the system journal and the journals
  84     of other users. Members of the groups <literal>systemd-journal</literal>, <literal>adm</literal>, and
  85     <literal>wheel</literal> can read all journal files. Note that the two latter groups traditionally have
  86     additional privileges specified by the distribution. Members of the <literal>wheel</literal> group can
  87     often perform administrative tasks.</para>
  88
  89     <para>The output is paged through <command>less</command> by default, and long lines are "truncated" to
  90     screen width. The hidden part can be viewed by using the left-arrow and right-arrow keys. Paging can be
  91     disabled; see the <option>--no-pager</option> option and the "Environment" section below.</para>
  92
  93     <para>When outputting to a tty, lines are colored according to priority: lines of level ERROR and higher
  94     are colored red; lines of level NOTICE and higher are highlighted; lines of level DEBUG are colored
  95     lighter grey; other lines are displayed normally.</para>
  96   </refsect1>
  97
  98   <refsect1>
  99     <title>Source Options</title>
 100
 101     <para>The following options control where to read journal records from:</para>
 102
 103     <variablelist>
 104       <varlistentry>
 105         <term><option>--system</option></term>
 106         <term><option>--user</option></term>
 107
 108         <listitem><para>Show messages from system services and the kernel (with
 109         <option>--system</option>). Show messages from service of current user (with
 110         <option>--user</option>).  If neither is specified, show all messages that the user can see.
 111         </para></listitem>
 112       </varlistentry>
 113
 114       <varlistentry>
 115         <term><option>-M</option></term>
 116         <term><option>--machine=</option></term>
 117
 118         <listitem><para>Show messages from a running, local container. Specify a container name to connect
 119         to.</para></listitem>
 120       </varlistentry>
 121
 122       <varlistentry>
 123         <term><option>-m</option></term>
 124         <term><option>--merge</option></term>
 125
 126         <listitem><para>Show entries interleaved from all available journals, including remote
 127         ones.</para></listitem>
 128       </varlistentry>
 129
 130       <varlistentry>
 131         <term><option>-D <replaceable>DIR</replaceable></option></term>
 132         <term><option>--directory=<replaceable>DIR</replaceable></option></term>
 133
 134         <listitem><para>Takes a directory path as argument. If specified, journalctl will operate on the
 135         specified journal directory <replaceable>DIR</replaceable> instead of the default runtime and system
 136         journal paths.</para></listitem>
 137       </varlistentry>
 138
 139       <varlistentry>
 140         <term><option>--file=<replaceable>GLOB</replaceable></option></term>
 141
 142         <listitem><para>Takes a file glob as an argument. If specified, journalctl will operate on the
 143         specified journal files matching <replaceable>GLOB</replaceable> instead of the default runtime and
 144         system journal paths. May be specified multiple times, in which case files will be suitably
 145         interleaved.</para></listitem>
 146       </varlistentry>
 147
 148       <varlistentry>
 149         <term><option>--root=<replaceable>ROOT</replaceable></option></term>
 150
 151         <listitem><para>Takes a directory path as an argument. If specified, <command>journalctl</command>
 152         will operate on journal directories and catalog file hierarchy underneath the specified directory
 153         instead of the root directory (e.g. <option>--update-catalog</option> will create
 154         <filename><replaceable>ROOT</replaceable>/var/lib/systemd/catalog/database</filename>, and journal
 155         files under <filename><replaceable>ROOT</replaceable>/run/journal/</filename> or
 156         <filename><replaceable>ROOT</replaceable>/var/log/journal/</filename> will be displayed).
 157         </para></listitem>
 158       </varlistentry>
 159
 160       <varlistentry>
 161         <term><option>--image=<replaceable>IMAGE</replaceable></option></term>
 162
 163         <listitem><para>Takes a path to a disk image file or block device node. If specified,
 164         <command>journalctl</command> will operate on the file system in the indicated disk image. This
 165         option is similar to <option>--root=</option>, but operates on file systems stored in disk images or
 166         block devices, thus providing an easy way to extract log data from disk images. The disk image should
 167         either contain just a file system or a set of file systems within a GPT partition table, following
 168         the <ulink url="https://systemd.io/DISCOVERABLE_PARTITIONS">Discoverable Partitions
 169         Specification</ulink>. For further information on supported disk images, see
 170         <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
 171         switch of the same name.</para></listitem>
 172       </varlistentry>
 173
 174       <varlistentry>
 175         <term><option>--namespace=<replaceable>NAMESPACE</replaceable></option></term>
 176
 177         <listitem><para>Takes a journal namespace identifier string as argument. If not specified the data
 178         collected by the default namespace is shown. If specified shows the log data of the specified
 179         namespace instead. If the namespace is specified as <literal>*</literal> data from all namespaces is
 180         shown, interleaved. If the namespace identifier is prefixed with <literal>+</literal> data from the
 181         specified namespace and the default namespace is shown, interleaved, but no other. For details about
 182         journal namespaces see
 183         <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para></listitem>
 184       </varlistentry>
 185     </variablelist>
 186   </refsect1>
 187
 188   <refsect1>
 189     <title>Filtering Options</title>
 190
 191     <para>The following options control how to filter journal records:</para>
 192
 193     <variablelist>
 194       <varlistentry>
 195         <term><option>-S</option></term>
 196         <term><option>--since=</option></term>
 197         <term><option>-U</option></term>
 198         <term><option>--until=</option></term>
 199
 200         <listitem><para>Start showing entries on or newer than the specified date, or on or older than the
 201         specified date, respectively. Date specifications should be of the format <literal>2012-10-30
 202         18:17:16</literal>.  If the time part is omitted, <literal>00:00:00</literal> is assumed.  If only
 203         the seconds component is omitted, <literal>:00</literal> is assumed. If the date component is
 204         omitted, the current day is assumed. Alternatively the strings <literal>yesterday</literal>,
 205         <literal>today</literal>, <literal>tomorrow</literal> are understood, which refer to 00:00:00 of the
 206         day before the current day, the current day, or the day after the current day,
 207         respectively. <literal>now</literal> refers to the current time. Finally, relative times may be
 208         specified, prefixed with <literal>-</literal> or <literal>+</literal>, referring to times before or
 209         after the current time, respectively. For complete time and date specification, see
 210         <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>. Note
 211         that <option>--output=short-full</option> prints timestamps that follow precisely this format.
 212         </para></listitem>
 213       </varlistentry>
 214
 215       <varlistentry>
 216         <term><option>-c</option></term>
 217         <term><option>--cursor=</option></term>
 218
 219         <listitem><para>Start showing entries from the location in the journal specified by the passed
 220         cursor.</para></listitem>
 221       </varlistentry>
 222
 223       <varlistentry>
 224         <term><option>--after-cursor=</option></term>
 225
 226         <listitem><para>Start showing entries from the location in the journal <emphasis>after</emphasis>
 227         the location specified by the passed cursor.  The cursor is shown when the
 228         <option>--show-cursor</option> option is used.</para></listitem>
 229       </varlistentry>
 230
 231       <varlistentry>
 232         <term><option>--cursor-file=<replaceable>FILE</replaceable></option></term>
 233
 234         <listitem><para>If <replaceable>FILE</replaceable> exists and contains a cursor, start showing
 235         entries <emphasis>after</emphasis> this location.  Otherwise show entries according to the other
 236         given options. At the end, write the cursor of the last entry to
 237         <replaceable>FILE</replaceable>. Use this option to continually read the journal by sequentially
 238         calling <command>journalctl</command>.</para></listitem>
 239       </varlistentry>
 240
 241       <varlistentry>
 242         <term><option>-b <optional><optional><replaceable>ID</replaceable></optional><optional><replaceable>±offset</replaceable></optional>|<constant>all</constant></optional></option></term>
 243         <term><option>--boot<optional>=<optional><replaceable>ID</replaceable></optional><optional><replaceable>±offset</replaceable></optional>|<constant>all</constant></optional></option></term>
 244
 245         <listitem><para>Show messages from a specific boot. This will add a match for
 246         <literal>_BOOT_ID=</literal>.</para>
 247
 248         <para>The argument may be empty, in which case logs for the current boot will be shown.</para>
 249
 250         <para>If the boot ID is omitted, a positive <replaceable>offset</replaceable> will look up the boots
 251         starting from the beginning of the journal, and an equal-or-less-than zero
 252         <replaceable>offset</replaceable> will look up boots starting from the end of the journal. Thus,
 253         <constant>1</constant> means the first boot found in the journal in chronological order,
 254         <constant>2</constant> the second and so on; while <constant>-0</constant> is the last boot,
 255         <constant>-1</constant> the boot before last, and so on. An empty <replaceable>offset</replaceable>
 256         is equivalent to specifying <constant>-0</constant>, except when the current boot is not the last
 257         boot (e.g. because <option>--directory</option> was specified to look at logs from a different
 258         machine).</para>
 259
 260         <para>If the 32-character <replaceable>ID</replaceable> is specified, it may optionally be followed
 261         by <replaceable>offset</replaceable> which identifies the boot relative to the one given by boot
 262         <replaceable>ID</replaceable>. Negative values mean earlier boots and positive values mean later
 263         boots. If <replaceable>offset</replaceable> is not specified, a value of zero is assumed, and the
 264         logs for the boot given by <replaceable>ID</replaceable> are shown.</para>
 265
 266         <para>The special argument <constant>all</constant> can be used to negate the effect of an earlier
 267         use of <option>-b</option>.</para></listitem>
 268       </varlistentry>
 269
 270       <varlistentry>
 271         <term><option>-u</option></term>
 272         <term><option>--unit=<replaceable>UNIT</replaceable>|<replaceable>PATTERN</replaceable></option></term>
 273
 274         <listitem><para>Show messages for the specified systemd unit <replaceable>UNIT</replaceable> (such as
 275         a service unit), or for any of the units matched by <replaceable>PATTERN</replaceable>.  If a pattern
 276         is specified, a list of unit names found in the journal is compared with the specified pattern and
 277         all that match are used. For each unit name, a match is added for messages from the unit
 278         (<literal>_SYSTEMD_UNIT=<replaceable>UNIT</replaceable></literal>), along with additional matches for
 279         messages from systemd and messages about coredumps for the specified unit. A match is also added for
 280         <literal>_SYSTEMD_SLICE=<replaceable>UNIT</replaceable></literal>, such that if the provided
 281         <replaceable>UNIT</replaceable> is a
 282         <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 283         unit, all logs of children of the slice will be shown.</para>
 284
 285         <para>This parameter can be specified multiple times.</para></listitem>
 286       </varlistentry>
 287
 288       <varlistentry>
 289         <term><option>--user-unit=</option></term>
 290
 291         <listitem><para>Show messages for the specified user session unit. This will add a match for messages
 292         from the unit (<literal>_SYSTEMD_USER_UNIT=</literal> and <literal>_UID=</literal>) and additional
 293         matches for messages from session systemd and messages about coredumps for the specified unit. A
 294         match is also added for <literal>_SYSTEMD_USER_SLICE=<replaceable>UNIT</replaceable></literal>, such
 295         that if the provided <replaceable>UNIT</replaceable> is a
 296         <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 297         unit, all logs of children of the unit will be shown.</para>
 298
 299         <para>This parameter can be specified multiple times.</para></listitem>
 300       </varlistentry>
 301
 302       <varlistentry>
 303         <term><option>-t</option></term>
 304         <term><option>--identifier=<replaceable>SYSLOG_IDENTIFIER</replaceable></option></term>
 305
 306         <listitem><para>Show messages for the specified syslog identifier
 307         <replaceable>SYSLOG_IDENTIFIER</replaceable>.</para>
 308
 309         <para>This parameter can be specified multiple times.</para></listitem>
 310       </varlistentry>
 311
 312       <varlistentry>
 313         <term><option>-p</option></term>
 314         <term><option>--priority=</option></term>
 315
 316         <listitem><para>Filter output by message priorities or priority ranges. Takes either a single numeric
 317         or textual log level (i.e. between 0/<literal>emerg</literal> and 7/<literal>debug</literal>), or a
 318         range of numeric/text log levels in the form FROM..TO. The log levels are the usual syslog log levels
 319         as documented in <citerefentry
 320         project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 321         i.e. <literal>emerg</literal> (0), <literal>alert</literal> (1), <literal>crit</literal> (2),
 322         <literal>err</literal> (3), <literal>warning</literal> (4), <literal>notice</literal> (5),
 323         <literal>info</literal> (6), <literal>debug</literal> (7). If a single log level is specified, all
 324         messages with this log level or a lower (hence more important) log level are shown. If a range is
 325         specified, all messages within the range are shown, including both the start and the end value of the
 326         range. This will add <literal>PRIORITY=</literal> matches for the specified
 327         priorities.</para></listitem>
 328       </varlistentry>
 329
 330       <varlistentry>
 331         <term><option>--facility=</option></term>
 332
 333         <listitem><para>Filter output by syslog facility. Takes a comma-separated list of numbers or
 334         facility names. The names are the usual syslog facilities as documented in <citerefentry
 335         project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 336         <option>--facility=help</option> may be used to display a list of known facility names and exit.
 337         </para></listitem>
 338       </varlistentry>
 339
 340       <varlistentry>
 341         <term><option>-g</option></term>
 342         <term><option>--grep=</option></term>
 343
 344         <listitem><para>Filter output to entries where the <varname>MESSAGE=</varname> field matches the
 345         specified regular expression. PERL-compatible regular expressions are used, see <citerefentry
 346         project='url'><refentrytitle
 347         url='http://pcre.org/current/doc/html/pcre2pattern.html'>pcre2pattern</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 348         for a detailed description of the syntax.</para>
 349
 350         <para>If the pattern is all lowercase, matching is case insensitive.  Otherwise, matching is case
 351         sensitive. This can be overridden with the <option>--case-sensitive</option> option, see
 352         below.</para></listitem>
 353       </varlistentry>
 354
 355       <varlistentry>
 356         <term><option>--case-sensitive<optional>=BOOLEAN</optional></option></term>
 357
 358         <listitem><para>Make pattern matching case sensitive or case insensitive.</para></listitem>
 359       </varlistentry>
 360
 361       <varlistentry>
 362         <term><option>-k</option></term>
 363         <term><option>--dmesg</option></term>
 364
 365         <listitem><para>Show only kernel messages. This implies <option>-b</option> and adds the match
 366         <literal>_TRANSPORT=kernel</literal>.</para></listitem>
 367       </varlistentry>
 368     </variablelist>
 369   </refsect1>
 370
 371   <refsect1>
 372     <title>Output Options</title>
 373
 374     <para>The following options control how journal records are printed:</para>
 375
 376     <variablelist>
 377       <varlistentry>
 378         <term><option>-o</option></term>
 379         <term><option>--output=</option></term>
 380
 381         <listitem><para>Controls the formatting of the journal entries that are shown. Takes one of the
 382         following options:</para>
 383
 384         <variablelist>
 385           <varlistentry>
 386             <term><option>short</option></term>
 387             <listitem><para>is the default and generates an output that is mostly identical to the
 388             formatting of classic syslog files, showing one line per journal entry.</para></listitem>
 389           </varlistentry>
 390
 391           <varlistentry>
 392             <term><option>short-full</option></term>
 393             <listitem><para>is very similar, but shows timestamps in the format the
 394             <option>--since=</option> and <option>--until=</option> options accept. Unlike the timestamp
 395             information shown in <option>short</option> output mode this mode includes weekday, year and
 396             timezone information in the output, and is locale-independent.</para></listitem>
 397           </varlistentry>
 398
 399           <varlistentry>
 400             <term><option>short-iso</option></term>
 401             <listitem><para>is very similar, but shows ISO 8601 wallclock timestamps.</para></listitem>
 402           </varlistentry>
 403
 404           <varlistentry>
 405             <term><option>short-iso-precise</option></term>
 406             <listitem><para>as for <option>short-iso</option> but includes full microsecond
 407             precision.</para></listitem>
 408           </varlistentry>
 409
 410           <varlistentry>
 411             <term><option>short-precise</option></term>
 412             <listitem><para>is very similar, but shows classic syslog timestamps with full microsecond
 413             precision.</para></listitem>
 414           </varlistentry>
 415
 416           <varlistentry>
 417             <term><option>short-monotonic</option></term>
 418             <listitem><para>is very similar, but shows monotonic timestamps instead of wallclock
 419             timestamps.</para></listitem>
 420           </varlistentry>
 421
 422           <varlistentry>
 423             <term><option>short-delta</option></term>
 424             <listitem><para>as for <option>short-monotonic</option> but includes the time difference
 425             to the previous entry.
 426             Maybe unreliable time differences are marked by a <literal>*</literal>.</para></listitem>
 427           </varlistentry>
 428
 429           <varlistentry>
 430             <term><option>short-unix</option></term>
 431             <listitem><para>is very similar, but shows seconds passed since January 1st 1970 UTC instead of
 432             wallclock timestamps ("UNIX time"). The time is shown with microsecond accuracy.</para></listitem>
 433           </varlistentry>
 434
 435           <varlistentry>
 436             <term><option>verbose</option></term>
 437             <listitem><para>shows the full-structured entry items with all fields.</para></listitem>
 438           </varlistentry>
 439
 440           <varlistentry>
 441             <term><option>export</option></term>
 442             <listitem><para>serializes the journal into a binary (but mostly text-based) stream suitable
 443             for backups and network transfer (see <ulink
 444             url="https://systemd.io/JOURNAL_EXPORT_FORMATS#journal-export-format">Journal Export
 445             Format</ulink> for more information). To import the binary stream back into native journald
 446             format use
 447             <citerefentry><refentrytitle>systemd-journal-remote</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para></listitem>
 448           </varlistentry>
 449
 450           <varlistentry>
 451             <term><option>json</option></term>
 452             <listitem><para>formats entries as JSON objects, separated by newline characters (see <ulink
 453             url="https://systemd.io/JOURNAL_EXPORT_FORMATS#journal-json-format">Journal JSON Format</ulink>
 454             for more information). Field values are generally encoded as JSON strings, with three exceptions:
 455             <orderedlist>
 456               <listitem><para>Fields larger than 4096 bytes are encoded as <constant>null</constant>
 457               values. (This may be turned off by passing <option>--all</option>, but be aware that this may
 458               allocate overly long JSON objects.)</para></listitem>
 459
 460               <listitem><para>Journal entries permit non-unique fields within the same log entry. JSON does
 461               not allow non-unique fields within objects. Due to this, if a non-unique field is encountered a
 462               JSON array is used as field value, listing all field values as elements.</para></listitem>
 463
 464               <listitem><para>Fields containing non-printable or non-UTF8 bytes are encoded as arrays
 465               containing the raw bytes individually formatted as unsigned numbers.</para></listitem>
 466             </orderedlist>
 467
 468             Note that this encoding is reversible (with the exception of the size limit).</para></listitem>
 469           </varlistentry>
 470
 471           <varlistentry>
 472             <term><option>json-pretty</option></term>
 473             <listitem><para>formats entries as JSON data structures, but formats them in multiple lines in
 474             order to make them more readable by humans.</para></listitem>
 475           </varlistentry>
 476
 477           <varlistentry>
 478             <term><option>json-sse</option></term>
 479             <listitem><para>formats entries as JSON data structures, but wraps them in a format suitable for
 480             <ulink
 481             url="https://developer.mozilla.org/en-US/docs/Server-sent_events/Using_server-sent_events">Server-Sent
 482             Events</ulink>.</para></listitem>
 483           </varlistentry>
 484
 485           <varlistentry>
 486             <term><option>json-seq</option></term>
 487             <listitem><para>formats entries as JSON data structures, but prefixes them with an ASCII Record
 488             Separator character (0x1E) and suffixes them with an ASCII Line Feed character (0x0A), in
 489             accordance with <ulink url="https://tools.ietf.org/html/rfc7464">JavaScript Object Notation
 490             (JSON) Text Sequences </ulink> (<literal>application/json-seq</literal>).</para></listitem>
 491           </varlistentry>
 492
 493           <varlistentry>
 494             <term><option>cat</option></term>
 495             <listitem><para>generates a very terse output, only showing the actual message of each journal
 496             entry with no metadata, not even a timestamp. If combined with the
 497             <option>--output-fields=</option> option will output the listed fields for each log record,
 498             instead of the message.</para></listitem>
 499           </varlistentry>
 500
 501           <varlistentry>
 502             <term><option>with-unit</option></term>
 503             <listitem><para>similar to <option>short-full</option>, but prefixes the unit and user unit names
 504             instead of the traditional syslog identifier. Useful when using templated instances, as it will
 505             include the arguments in the unit names.</para></listitem>
 506           </varlistentry>
 507         </variablelist></listitem>
 508       </varlistentry>
 509
 510       <varlistentry>
 511         <term><option>--output-fields=</option></term>
 512
 513         <listitem><para>A comma separated list of the fields which should be included in the output. This
 514         has an effect only for the output modes which would normally show all fields
 515         (<option>verbose</option>, <option>export</option>, <option>json</option>,
 516         <option>json-pretty</option>, <option>json-sse</option> and <option>json-seq</option>), as well as
 517         on <option>cat</option>. For the former, the <literal>__CURSOR</literal>,
 518         <literal>__REALTIME_TIMESTAMP</literal>, <literal>__MONOTONIC_TIMESTAMP</literal>, and
 519         <literal>_BOOT_ID</literal> fields are always printed.</para></listitem>
 520       </varlistentry>
 521
 522       <varlistentry>
 523         <term><option>-n</option></term>
 524         <term><option>--lines=</option></term>
 525
 526         <listitem><para>Show the most recent journal events and limit the number of events shown. If
 527         <option>--follow</option> is used, this option is implied. The argument is a positive integer or
 528         <literal>all</literal> to disable line limiting. The default value is 10 if no argument is
 529         given.</para></listitem>
 530       </varlistentry>
 531
 532       <varlistentry>
 533         <term><option>-r</option></term>
 534         <term><option>--reverse</option></term>
 535
 536         <listitem><para>Reverse output so that the newest entries are displayed first.</para></listitem>
 537       </varlistentry>
 538
 539       <varlistentry>
 540         <term><option>--show-cursor</option></term>
 541
 542         <listitem><para>The cursor is shown after the last entry after two dashes:</para>
 543         <programlisting>-- cursor: s=0639…</programlisting>
 544         <para>The format of the cursor is private and subject to change.</para></listitem>
 545       </varlistentry>
 546
 547       <varlistentry>
 548         <term><option>--utc</option></term>
 549
 550         <listitem><para>Express time in Coordinated Universal Time (UTC).</para></listitem>
 551       </varlistentry>
 552
 553       <varlistentry>
 554         <term><option>-x</option></term>
 555         <term><option>--catalog</option></term>
 556
 557         <listitem><para>Augment log lines with explanation texts from the message catalog. This will add
 558         explanatory help texts to log messages in the output where this is available. These short help texts
 559         will explain the context of an error or log event, possible solutions, as well as pointers to support
 560         forums, developer documentation, and any other relevant manuals. Note that help texts are not
 561         available for all messages, but only for selected ones. For more information on the message catalog,
 562         please refer to the <ulink url="https://www.freedesktop.org/wiki/Software/systemd/catalog">Message
 563         Catalog Developer Documentation</ulink>.</para>
 564
 565         <para>Note: when attaching <command>journalctl</command> output to bug reports, please do
 566         <emphasis>not</emphasis> use <option>-x</option>.</para></listitem>
 567       </varlistentry>
 568
 569       <varlistentry>
 570         <term><option>--no-hostname</option></term>
 571
 572         <listitem><para>Don't show the hostname field of log messages originating from the local host. This
 573         switch has an effect only on the <option>short</option> family of output modes (see above).</para>
 574
 575         <para>Note: this option does not remove occurrences of the hostname from log entries themselves, so
 576         it does not prevent the hostname from being visible in the logs.</para></listitem>
 577       </varlistentry>
 578
 579       <varlistentry>
 580         <term><option>--no-full</option></term>
 581         <term><option>--full</option></term>
 582         <term><option>-l</option></term>
 583
 584         <listitem><para>Ellipsize fields when they do not fit in available columns.  The default is to show
 585         full fields, allowing them to wrap or be truncated by the pager, if one is used.</para>
 586
 587         <para>The old options <option>-l</option>/<option>--full</option> are not useful anymore, except to
 588         undo <option>--no-full</option>.</para></listitem>
 589       </varlistentry>
 590
 591       <varlistentry>
 592         <term><option>-a</option></term>
 593         <term><option>--all</option></term>
 594
 595         <listitem><para>Show all fields in full, even if they include unprintable characters or are very
 596         long. By default, fields with unprintable characters are abbreviated as "blob data". (Note that the
 597         pager may escape unprintable characters again.)</para></listitem>
 598       </varlistentry>
 599
 600       <varlistentry>
 601         <term><option>-f</option></term>
 602         <term><option>--follow</option></term>
 603
 604         <listitem><para>Show only the most recent journal entries, and continuously print new entries as
 605         they are appended to the journal.</para></listitem>
 606       </varlistentry>
 607
 608       <varlistentry>
 609         <term><option>--no-tail</option></term>
 610
 611         <listitem><para>Show all stored output lines, even in follow mode. Undoes the effect of
 612         <option>--lines=</option>.</para></listitem>
 613       </varlistentry>
 614
 615       <varlistentry>
 616         <term><option>-q</option></term>
 617         <term><option>--quiet</option></term>
 618
 619         <listitem><para>Suppresses all informational messages (i.e. "-- Journal begins at …", "-- Reboot
 620         --"), any warning messages regarding inaccessible system journals when run as a normal
 621         user.</para></listitem>
 622       </varlistentry>
 623     </variablelist>
 624   </refsect1>
 625
 626   <refsect1>
 627     <title>Pager Control Options</title>
 628
 629     <para>The following options control page support:</para>
 630
 631     <variablelist>
 632
 633       <xi:include href="standard-options.xml" xpointer="no-pager" />
 634
 635       <varlistentry>
 636         <term><option>-e</option></term>
 637         <term><option>--pager-end</option></term>
 638
 639         <listitem><para>Immediately jump to the end of the journal inside the implied pager tool. This
 640         implies <option>-n1000</option> to guarantee that the pager will not buffer logs of unbounded
 641         size. This may be overridden with an explicit <option>-n</option> with some other numeric value,
 642         while <option>-nall</option> will disable this cap.  Note that this option is only supported for
 643         the <citerefentry
 644         project='man-pages'><refentrytitle>less</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 645         pager.</para></listitem>
 646       </varlistentry>
 647     </variablelist>
 648   </refsect1>
 649
 650   <refsect1>
 651     <title>Forward Secure Sealing (FSS) Options</title>
 652
 653     <para>The following options make be used together with the <option>--setup-keys</option> command, see below.</para>
 654
 655     <variablelist>
 656       <varlistentry>
 657         <term><option>--interval=</option></term>
 658
 659         <listitem><para>Specifies the change interval for the sealing key when generating an FSS key pair
 660         with <option>--setup-keys</option>. Shorter intervals increase CPU consumption but shorten the time
 661         range of undetectable journal alterations. Defaults to 15min.</para></listitem>
 662       </varlistentry>
 663
 664       <varlistentry>
 665         <term><option>--verify-key=</option></term>
 666
 667         <listitem><para>Specifies the FSS verification key to use for the <option>--verify</option>
 668         operation.</para></listitem>
 669       </varlistentry>
 670
 671       <varlistentry>
 672         <term><option>--force</option></term>
 673
 674         <listitem><para>When <option>--setup-keys</option> is passed and Forward Secure Sealing (FSS) has
 675         already been configured, recreate FSS keys.</para></listitem>
 676       </varlistentry>
 677     </variablelist>
 678   </refsect1>
 679
 680   <refsect1>
 681     <title>Commands</title>
 682
 683     <para>The following commands are understood. If none is specified the default is to display journal records.</para>
 684
 685     <variablelist>
 686       <varlistentry>
 687         <term><option>-N</option></term>
 688         <term><option>--fields</option></term>
 689
 690         <listitem><para>Print all field names currently used in all entries of the journal.</para></listitem>
 691       </varlistentry>
 692
 693       <varlistentry>
 694         <term><option>-F</option></term>
 695         <term><option>--field=</option></term>
 696
 697         <listitem><para>Print all possible data values the specified field can take in all entries of the
 698         journal.</para></listitem>
 699       </varlistentry>
 700
 701       <varlistentry>
 702         <term><option>--list-boots</option></term>
 703
 704         <listitem><para>Show a tabular list of boot numbers (relative to the current boot), their IDs, and
 705         the timestamps of the first and last message pertaining to the boot.</para></listitem>
 706       </varlistentry>
 707
 708       <varlistentry>
 709         <term><option>--disk-usage</option></term>
 710
 711         <listitem><para>Shows the current disk usage of all journal files. This shows the sum of the disk
 712         usage of all archived and active journal files.</para></listitem>
 713       </varlistentry>
 714
 715       <varlistentry>
 716         <term><option>--vacuum-size=</option></term>
 717         <term><option>--vacuum-time=</option></term>
 718         <term><option>--vacuum-files=</option></term>
 719
 720         <listitem><para>Removes the oldest archived journal files until the disk space they use falls below
 721         the specified size (specified with the usual <literal>K</literal>, <literal>M</literal>,
 722         <literal>G</literal> and <literal>T</literal> suffixes), or all archived journal files contain no
 723         data older than the specified timespan (specified with the usual <literal>s</literal>,
 724         <literal>m</literal>, <literal>h</literal>, <literal>days</literal>, <literal>months</literal>,
 725         <literal>weeks</literal> and <literal>years</literal> suffixes), or no more than the specified
 726         number of separate journal files remain. Note that running <option>--vacuum-size=</option> has only
 727         an indirect effect on the output shown by <option>--disk-usage</option>, as the latter includes
 728         active journal files, while the vacuuming operation only operates on archived journal
 729         files. Similarly, <option>--vacuum-files=</option> might not actually reduce the number of journal
 730         files to below the specified number, as it will not remove active journal files.</para>
 731
 732         <para><option>--vacuum-size=</option>, <option>--vacuum-time=</option> and
 733         <option>--vacuum-files=</option> may be combined in a single invocation to enforce any combination
 734         of a size, a time and a number of files limit on the archived journal files. Specifying any of
 735         these three parameters as zero is equivalent to not enforcing the specific limit, and is thus
 736         redundant.</para>
 737
 738         <para>These three switches may also be combined with <option>--rotate</option> into one command. If
 739         so, all active files are rotated first, and the requested vacuuming operation is executed right
 740         after. The rotation has the effect that all currently active files are archived (and potentially new,
 741         empty journal files opened as replacement), and hence the vacuuming operation has the greatest effect
 742         as it can take all log data written so far into account.</para></listitem>
 743       </varlistentry>
 744
 745       <varlistentry>
 746         <term><option>--verify</option></term>
 747
 748         <listitem><para>Check the journal file for internal consistency. If the file has been generated
 749         with FSS enabled and the FSS verification key has been specified with
 750         <option>--verify-key=</option>, authenticity of the journal file is verified.</para></listitem>
 751       </varlistentry>
 752
 753       <varlistentry>
 754         <term><option>--sync</option></term>
 755
 756         <listitem><para>Asks the journal daemon to write all yet unwritten journal data to the backing file
 757         system and synchronize all journals. This call does not return until the synchronization operation
 758         is complete. This command guarantees that any log messages written before its invocation are safely
 759         stored on disk at the time it returns.</para></listitem>
 760       </varlistentry>
 761
 762       <varlistentry>
 763         <term><option>--relinquish-var</option></term>
 764
 765         <listitem><para>Asks the journal daemon for the reverse operation to <option>--flush</option>: if
 766         requested the daemon will write further log data to <filename>/run/log/journal/</filename> and
 767         stops writing to <filename>/var/log/journal/</filename>. A subsequent call to
 768         <option>--flush</option> causes the log output to switch back to
 769         <filename>/var/log/journal/</filename>, see above.</para></listitem>
 770       </varlistentry>
 771
 772       <varlistentry>
 773         <term><option>--smart-relinquish-var</option></term>
 774
 775         <listitem><para>Similar to <option>--relinquish-var</option>, but executes no operation if the root
 776         file system and <filename>/var/lib/journal/</filename> reside on the same mount point. This operation
 777         is used during system shutdown in order to make the journal daemon stop writing data to
 778         <filename>/var/log/journal/</filename> in case that directory is located on a mount point that needs
 779         to be unmounted.</para></listitem>
 780       </varlistentry>
 781
 782       <varlistentry>
 783         <term><option>--flush</option></term>
 784
 785         <listitem><para>Asks the journal daemon to flush any log data stored in
 786         <filename>/run/log/journal/</filename> into <filename>/var/log/journal/</filename>, if persistent
 787         storage is enabled. This call does not return until the operation is complete. Note that this call is
 788         idempotent: the data is only flushed from <filename>/run/log/journal/</filename> into
 789         <filename>/var/log/journal/</filename> once during system runtime (but see
 790         <option>--relinquish-var</option> below), and this command exits cleanly without executing any
 791         operation if this has already happened. This command effectively guarantees that all data is flushed
 792         to <filename>/var/log/journal/</filename> at the time it returns.</para></listitem>
 793       </varlistentry>
 794
 795       <varlistentry>
 796         <term><option>--rotate</option></term>
 797
 798         <listitem><para>Asks the journal daemon to rotate journal files. This call does not return until
 799         the rotation operation is complete. Journal file rotation has the effect that all currently active
 800         journal files are marked as archived and renamed, so that they are never written to in future. New
 801         (empty) journal files are then created in their place. This operation may be combined with
 802         <option>--vacuum-size=</option>, <option>--vacuum-time=</option> and
 803         <option>--vacuum-file=</option> into a single command, see above.</para></listitem>
 804       </varlistentry>
 805
 806       <varlistentry>
 807         <term><option>--header</option></term>
 808
 809         <listitem><para>Instead of showing journal contents, show internal header information of the
 810         journal fields accessed.</para>
 811
 812         <para>This option is particularly useful when trying to identify out-of-order journal entries, as
 813         happens for example when the machine is booted with the wrong system time.</para></listitem>
 814       </varlistentry>
 815
 816       <varlistentry>
 817         <term><option>--list-catalog <optional><replaceable>128-bit-ID…</replaceable></optional></option></term>
 818
 819         <listitem><para>List the contents of the message catalog as a table of message IDs, plus their
 820         short description strings.</para>
 821
 822         <para>If any <replaceable>128-bit-ID</replaceable>s are specified, only those entries are
 823         shown.</para></listitem>
 824       </varlistentry>
 825
 826       <varlistentry>
 827         <term><option>--dump-catalog <optional><replaceable>128-bit-ID…</replaceable></optional></option></term>
 828
 829         <listitem><para>Show the contents of the message catalog, with entries separated by a line
 830         consisting of two dashes and the ID (the format is the same as <filename>.catalog</filename>
 831         files).</para>
 832
 833         <para>If any <replaceable>128-bit-ID</replaceable>s are specified, only those entries are
 834         shown.</para></listitem>
 835       </varlistentry>
 836
 837       <varlistentry>
 838         <term><option>--update-catalog</option></term>
 839
 840         <listitem><para>Update the message catalog index. This command needs to be executed each time new
 841         catalog files are installed, removed, or updated to rebuild the binary catalog
 842         index.</para></listitem>
 843       </varlistentry>
 844
 845       <varlistentry>
 846         <term><option>--setup-keys</option></term>
 847
 848         <listitem><para>Instead of showing journal contents, generate a new key pair for Forward Secure
 849         Sealing (FSS). This will generate a sealing key and a verification key. The sealing key is stored in
 850         the journal data directory and shall remain on the host. The verification key should be stored
 851         externally. Refer to the <option>Seal=</option> option in
 852         <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
 853         information on Forward Secure Sealing and for a link to a refereed scholarly paper detailing the
 854         cryptographic theory it is based on.</para></listitem>
 855       </varlistentry>
 856
 857       <xi:include href="standard-options.xml" xpointer="help" />
 858       <xi:include href="standard-options.xml" xpointer="version" />
 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 code is returned.</para>
 866   </refsect1>
 867
 868   <xi:include href="common-variables.xml" />
 869
 870   <refsect1>
 871     <title>Examples</title>
 872
 873     <para>Without arguments, all collected logs are shown unfiltered:</para>
 874
 875     <programlisting>journalctl</programlisting>
 876
 877     <para>With one match specified, all entries with a field matching the expression are shown:</para>
 878
 879     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service
 880 journalctl _SYSTEMD_CGROUP=/user.slice/user-42.slice/session-c1.scope</programlisting>
 881
 882     <para>If two different fields are matched, only entries matching both expressions at the same time are
 883     shown:</para>
 884
 885     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097</programlisting>
 886
 887     <para>If two matches refer to the same field, all entries matching either expression are shown:</para>
 888
 889     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _SYSTEMD_UNIT=dbus.service</programlisting>
 890
 891     <para>If the separator <literal>+</literal> is used, two expressions may be combined in a logical OR. The
 892     following will show all messages from the Avahi service process with the PID 28097 plus all messages from
 893     the D-Bus service (from any of its processes):</para>
 894
 895     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097 + _SYSTEMD_UNIT=dbus.service</programlisting>
 896
 897     <para>To show all fields emitted <emphasis>by</emphasis> a unit and <emphasis>about</emphasis> the unit,
 898     option <option>-u</option>/<option>--unit=</option> should be used. <command>journalctl -u
 899     <replaceable>name</replaceable></command> expands to a complex filter similar to
 900
 901     <programlisting>_SYSTEMD_UNIT=<replaceable>name</replaceable>.service
 902   + UNIT=<replaceable>name</replaceable>.service _PID=1
 903   + OBJECT_SYSTEMD_UNIT=<replaceable>name</replaceable>.service _UID=0
 904   + COREDUMP_UNIT=<replaceable>name</replaceable>.service _UID=0 MESSAGE_ID=fc2e22bc6ee647b6b90729ab34a250b1</programlisting>
 905
 906     (see
 907     <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 908     for an explanation of those patterns).</para>
 909
 910     <para>Show all logs generated by the D-Bus executable:</para>
 911
 912     <programlisting>journalctl /usr/bin/dbus-daemon</programlisting>
 913
 914     <para>Show all kernel logs from previous boot:</para>
 915
 916     <programlisting>journalctl -k -b -1</programlisting>
 917
 918     <para>Show a live log display from a system service <filename>apache.service</filename>:</para>
 919
 920     <programlisting>journalctl -f -u apache</programlisting>
 921   </refsect1>
 922
 923   <refsect1>
 924     <title>See Also</title>
 925     <para>
 926       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 927       <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 928       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 929       <citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 930       <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 931       <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 932       <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 933       <citerefentry><refentrytitle>systemd-journal-remote.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 934       <citerefentry><refentrytitle>systemd-journal-upload.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 935     </para>
 936   </refsect1>
 937 </refentry>