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/4.5/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>Print log entries from 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> is used to print the log entries stored in the journal by
  36     <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  37     and
  38     <citerefentry><refentrytitle>systemd-journal-remote.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
  39     </para>
  40
  41     <para>If called without parameters, it will show the contents of the journal accessible to the calling
  42     user, starting with the oldest entry collected.</para>
  43
  44     <para>If one or more match arguments are passed, the output is filtered accordingly. A match is in the
  45     format <literal>FIELD=VALUE</literal>, e.g. <literal>_SYSTEMD_UNIT=httpd.service</literal>, referring to
  46     the components of a structured journal entry. See
  47     <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
  48     for a list of well-known fields. If multiple matches are specified matching different fields, the log
  49     entries are filtered by both, i.e. the resulting output will show only entries matching all the specified
  50     matches of this kind. If two matches apply to the same field, then they are automatically matched as
  51     alternatives, i.e. the resulting output will show entries matching any of the specified matches for the
  52     same field. Finally, the character <literal>+</literal> may appear as a separate word between other terms
  53     on the command line. This causes all matches before and after to be combined in a disjunction
  54     (i.e. logical OR).</para>
  55
  56     <para>It is also possible to filter the entries by specifying an absolute file path as an argument. The
  57     file path may be a file or a symbolic link and the file must exist at the time of the query. If a file
  58     path refers to an executable binary, an <literal>_EXE=</literal> match for the canonicalized binary path
  59     is added to the query. If a file path refers to an executable script, a <literal>_COMM=</literal> match
  60     for the script name is added to the query. If a file path refers to a device node,
  61     <literal>_KERNEL_DEVICE=</literal> matches for the kernel name of the device and for each of its ancestor
  62     devices is added to the query. Symbolic links are dereferenced, kernel names are synthesized, and parent
  63     devices are identified from the environment at the time of the query. In general, a device node is the
  64     best proxy for an actual device, as log entries do not usually contain fields that identify an actual
  65     device. For the resulting log entries to be correct for the actual device, the relevant parts of the
  66     environment at the time the entry was logged, in particular the actual device corresponding to the device
  67     node, must have been the same as those at the time of the query. Because device nodes generally change
  68     their corresponding devices across reboots, specifying a device node path causes the resulting entries to
  69     be restricted to those from the current boot.</para>
  70
  71     <para>Additional constraints may be added using options <option>--boot</option>,
  72     <option>--unit=</option>, etc., to further limit what entries will be shown (logical AND).</para>
  73
  74     <para>Output is interleaved from all accessible journal files, whether they are rotated or currently
  75     being written, and regardless of whether they belong to the system itself or are accessible user
  76     journals. The <option>--header</option> option can be used to identify which files
  77     <emphasis>are</emphasis> being shown.</para>
  78
  79     <para>The set of journal files which will be used can be modified using the <option>--user</option>,
  80     <option>--system</option>, <option>--directory=</option>, and <option>--file=</option> options, see
  81     below.</para>
  82
  83     <para>All users are granted access to their private per-user journals. However, by default, only root and
  84     users who are members of a few special groups are granted access to the system journal and the journals
  85     of other users. Members of the groups <literal>systemd-journal</literal>, <literal>adm</literal>, and
  86     <literal>wheel</literal> can read all journal files. Note that the two latter groups traditionally have
  87     additional privileges specified by the distribution. Members of the <literal>wheel</literal> group can
  88     often perform administrative tasks.</para>
  89
  90     <para>The output is paged through <command>less</command> by default, and long lines are "truncated" to
  91     screen width. The hidden part can be viewed by using the left-arrow and right-arrow keys. Paging can be
  92     disabled; see the <option>--no-pager</option> option and the "Environment" section below.</para>
  93
  94     <para>When outputting to a tty, lines are colored according to priority: lines of level ERROR and higher
  95     are colored red; lines of level WARNING are colored yellow; lines of level NOTICE are highlighted;
  96     lines of level INFO are displayed normally; lines of level DEBUG are colored grey.</para>
  97
  98     <para>To write entries <emphasis>to</emphasis> the journal, a few methods may be used. In general, output
  99     from systemd units is automatically connected to the journal, see
 100     <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
 101     In addition,
 102     <citerefentry><refentrytitle>systemd-cat</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 103     may be used to send messages to the journal directly.</para>
 104   </refsect1>
 105
 106   <refsect1>
 107     <title>Source Options</title>
 108
 109     <para>The following options control where to read journal records from:</para>
 110
 111     <variablelist>
 112       <varlistentry>
 113         <term><option>--system</option></term>
 114         <term><option>--user</option></term>
 115
 116         <listitem><para>Show messages from system services and the kernel (with
 117         <option>--system</option>). Show messages from service of current user (with
 118         <option>--user</option>).  If neither is specified, show all messages that the user can see.
 119         </para>
 120
 121         <para>The <option>--user</option> option affects how <option>--unit=</option> arguments are
 122         treated. See <option>--unit=</option>.</para>
 123
 124         <para>Note that <option>--user</option> only works if persistent logging is enabled, via the
 125         <varname>Storage=</varname> setting in
 126         <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 127
 128         <xi:include href="version-info.xml" xpointer="v205"/></listitem>
 129       </varlistentry>
 130
 131       <varlistentry>
 132         <term><option>-M</option></term>
 133         <term><option>--machine=</option></term>
 134
 135         <listitem><para>Show messages from a running, local container. Specify a container name to connect
 136         to.</para>
 137
 138         <xi:include href="version-info.xml" xpointer="v209"/></listitem>
 139       </varlistentry>
 140
 141       <varlistentry>
 142         <term><option>-m</option></term>
 143         <term><option>--merge</option></term>
 144
 145         <listitem><para>Show entries interleaved from all available journals, including remote
 146         ones.</para>
 147
 148         <xi:include href="version-info.xml" xpointer="v190"/></listitem>
 149       </varlistentry>
 150
 151       <varlistentry>
 152         <term><option>-D <replaceable>DIR</replaceable></option></term>
 153         <term><option>--directory=<replaceable>DIR</replaceable></option></term>
 154
 155         <listitem><para>Takes a directory path as argument. If specified, journalctl will operate on the
 156         specified journal directory <replaceable>DIR</replaceable> instead of the default runtime and system
 157         journal paths.</para>
 158
 159         <xi:include href="version-info.xml" xpointer="v187"/></listitem>
 160       </varlistentry>
 161
 162       <varlistentry>
 163         <term><option>-i <replaceable>GLOB</replaceable></option></term>
 164         <term><option>--file=<replaceable>GLOB</replaceable></option></term>
 165
 166         <listitem><para>Takes a file glob as an argument. If specified, journalctl will operate on the
 167         specified journal files matching <replaceable>GLOB</replaceable> instead of the default runtime and
 168         system journal paths. May be specified multiple times, in which case files will be suitably
 169         interleaved.</para>
 170
 171         <xi:include href="version-info.xml" xpointer="v205"/></listitem>
 172       </varlistentry>
 173
 174       <varlistentry>
 175         <term><option>--root=<replaceable>ROOT</replaceable></option></term>
 176
 177         <listitem><para>Takes a directory path as an argument. If specified, <command>journalctl</command>
 178         will operate on journal directories and catalog file hierarchy underneath the specified directory
 179         instead of the root directory (e.g. <option>--update-catalog</option> will create
 180         <filename><replaceable>ROOT</replaceable>/var/lib/systemd/catalog/database</filename>, and journal
 181         files under <filename><replaceable>ROOT</replaceable>/run/journal/</filename> or
 182         <filename><replaceable>ROOT</replaceable>/var/log/journal/</filename> will be displayed).
 183         </para>
 184
 185         <xi:include href="version-info.xml" xpointer="v201"/></listitem>
 186       </varlistentry>
 187
 188       <varlistentry>
 189         <term><option>--image=<replaceable>IMAGE</replaceable></option></term>
 190
 191         <listitem><para>Takes a path to a disk image file or block device node. If specified,
 192         <command>journalctl</command> will operate on the file system in the indicated disk image. This
 193         option is similar to <option>--root=</option>, but operates on file systems stored in disk images or
 194         block devices, thus providing an easy way to extract log data from disk images. The disk image should
 195         either contain just a file system or a set of file systems within a GPT partition table, following
 196         the <ulink url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable Partitions
 197         Specification</ulink>. For further information on supported disk images, see
 198         <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
 199         switch of the same name.</para>
 200
 201         <xi:include href="version-info.xml" xpointer="v247"/></listitem>
 202       </varlistentry>
 203
 204       <xi:include href="standard-options.xml" xpointer="image-policy-open" />
 205
 206       <varlistentry>
 207         <term><option>--namespace=<replaceable>NAMESPACE</replaceable></option></term>
 208
 209         <listitem><para>Takes a journal namespace identifier string as argument. If not specified the data
 210         collected by the default namespace is shown. If specified shows the log data of the specified
 211         namespace instead. If the namespace is specified as <literal>*</literal> data from all namespaces is
 212         shown, interleaved. If the namespace identifier is prefixed with <literal>+</literal> data from the
 213         specified namespace and the default namespace is shown, interleaved, but no other. For details about
 214         journal namespaces see
 215         <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 216
 217         <xi:include href="version-info.xml" xpointer="v245"/></listitem>
 218       </varlistentry>
 219     </variablelist>
 220   </refsect1>
 221
 222   <refsect1>
 223     <title>Filtering Options</title>
 224
 225     <para>The following options control how to filter journal records:</para>
 226
 227     <variablelist>
 228       <varlistentry>
 229         <term><option>-S</option></term>
 230         <term><option>--since=</option></term>
 231         <term><option>-U</option></term>
 232         <term><option>--until=</option></term>
 233
 234         <listitem><para>Start showing entries on or newer than the specified date, or on or older than the
 235         specified date, respectively. Date specifications should be of the format <literal>2012-10-30
 236         18:17:16</literal>.  If the time part is omitted, <literal>00:00:00</literal> is assumed.  If only
 237         the seconds component is omitted, <literal>:00</literal> is assumed. If the date component is
 238         omitted, the current day is assumed. Alternatively the strings <literal>yesterday</literal>,
 239         <literal>today</literal>, <literal>tomorrow</literal> are understood, which refer to 00:00:00 of the
 240         day before the current day, the current day, or the day after the current day,
 241         respectively. <literal>now</literal> refers to the current time. Finally, relative times may be
 242         specified, prefixed with <literal>-</literal> or <literal>+</literal>, referring to times before or
 243         after the current time, respectively. For complete time and date specification, see
 244         <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>. Note
 245         that <option>--output=short-full</option> prints timestamps that follow precisely this format.
 246         </para>
 247
 248         <xi:include href="version-info.xml" xpointer="v195"/></listitem>
 249       </varlistentry>
 250
 251       <varlistentry>
 252         <term><option>-c</option></term>
 253         <term><option>--cursor=</option></term>
 254
 255         <listitem><para>Start showing entries from the location in the journal specified by the passed
 256         cursor.</para>
 257
 258         <xi:include href="version-info.xml" xpointer="v193"/></listitem>
 259       </varlistentry>
 260
 261       <varlistentry>
 262         <term><option>--after-cursor=</option></term>
 263
 264         <listitem><para>Start showing entries from the location in the journal <emphasis>after</emphasis>
 265         the location specified by the passed cursor.  The cursor is shown when the
 266         <option>--show-cursor</option> option is used.</para>
 267
 268         <xi:include href="version-info.xml" xpointer="v206"/></listitem>
 269       </varlistentry>
 270
 271       <varlistentry>
 272         <term><option>--cursor-file=<replaceable>FILE</replaceable></option></term>
 273
 274         <listitem><para>If <replaceable>FILE</replaceable> exists and contains a cursor, start showing
 275         entries <emphasis>after</emphasis> this location.  Otherwise show entries according to the other
 276         given options. At the end, write the cursor of the last entry to
 277         <replaceable>FILE</replaceable>. Use this option to continually read the journal by sequentially
 278         calling <command>journalctl</command>.</para>
 279
 280         <xi:include href="version-info.xml" xpointer="v242"/></listitem>
 281       </varlistentry>
 282
 283       <varlistentry>
 284         <term><option>-b <optional><optional><replaceable>ID</replaceable></optional><optional><replaceable>±offset</replaceable></optional>|<constant>all</constant></optional></option></term>
 285         <term><option>--boot<optional>=<optional><replaceable>ID</replaceable></optional><optional><replaceable>±offset</replaceable></optional>|<constant>all</constant></optional></option></term>
 286
 287         <listitem><para>Show messages from a specific boot. This will add a match for
 288         <literal>_BOOT_ID=</literal>.</para>
 289
 290         <para>The argument may be empty, in which case logs for the current boot will be shown.</para>
 291
 292         <para>If the boot ID is omitted, a positive <replaceable>offset</replaceable> will look up the boots
 293         starting from the beginning of the journal, and an equal-or-less-than zero
 294         <replaceable>offset</replaceable> will look up boots starting from the end of the journal. Thus,
 295         <constant>1</constant> means the first boot found in the journal in chronological order,
 296         <constant>2</constant> the second and so on; while <constant>-0</constant> is the last boot,
 297         <constant>-1</constant> the boot before last, and so on. An empty <replaceable>offset</replaceable>
 298         is equivalent to specifying <constant>-0</constant>, except when the current boot is not the last
 299         boot (e.g. because <option>--directory=</option> was specified to look at logs from a different
 300         machine).</para>
 301
 302         <para>If the 32-character <replaceable>ID</replaceable> is specified, it may optionally be followed
 303         by <replaceable>offset</replaceable> which identifies the boot relative to the one given by boot
 304         <replaceable>ID</replaceable>. Negative values mean earlier boots and positive values mean later
 305         boots. If <replaceable>offset</replaceable> is not specified, a value of zero is assumed, and the
 306         logs for the boot given by <replaceable>ID</replaceable> are shown.</para>
 307
 308         <para>The special argument <constant>all</constant> can be used to negate the effect of an earlier
 309         use of <option>-b</option>.</para>
 310
 311         <xi:include href="version-info.xml" xpointer="v186"/></listitem>
 312       </varlistentry>
 313
 314       <varlistentry>
 315         <term><option>-u</option></term>
 316         <term><option>--unit=<replaceable>UNIT</replaceable>|<replaceable>PATTERN</replaceable></option></term>
 317
 318         <listitem><para>Show messages for the specified systemd unit <replaceable>UNIT</replaceable> (such as
 319         a service unit), or for any of the units matched by <replaceable>PATTERN</replaceable>.  If a pattern
 320         is specified, a list of unit names found in the journal is compared with the specified pattern and
 321         all that match are used. For each unit name, a match is added for messages from the unit
 322         (<literal>_SYSTEMD_UNIT=<replaceable>UNIT</replaceable></literal>), along with additional matches for
 323         messages from systemd and messages about coredumps for the specified unit. A match is also added for
 324         <literal>_SYSTEMD_SLICE=<replaceable>UNIT</replaceable></literal>, such that if the provided
 325         <replaceable>UNIT</replaceable> is a
 326         <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 327         unit, all logs of children of the slice will be shown.</para>
 328
 329         <para>With <option>--user</option>, all <option>--unit=</option> arguments will be converted to match
 330         user messages as if specified with <option>--user-unit=</option>.</para>
 331
 332         <para>This parameter can be specified multiple times.</para>
 333
 334         <xi:include href="version-info.xml" xpointer="v195"/></listitem>
 335       </varlistentry>
 336
 337       <varlistentry>
 338         <term><option>--user-unit=</option></term>
 339
 340         <listitem><para>Show messages for the specified user session unit. This will add a match for messages
 341         from the unit (<literal>_SYSTEMD_USER_UNIT=</literal> and <literal>_UID=</literal>) and additional
 342         matches for messages from session systemd and messages about coredumps for the specified unit. A
 343         match is also added for <literal>_SYSTEMD_USER_SLICE=<replaceable>UNIT</replaceable></literal>, such
 344         that if the provided <replaceable>UNIT</replaceable> is a
 345         <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 346         unit, all logs of children of the unit will be shown.</para>
 347
 348         <para>This parameter can be specified multiple times.</para>
 349
 350         <xi:include href="version-info.xml" xpointer="v198"/></listitem>
 351       </varlistentry>
 352
 353       <varlistentry>
 354         <term><option>-t</option></term>
 355         <term><option>--identifier=<replaceable>SYSLOG_IDENTIFIER</replaceable></option></term>
 356
 357         <listitem><para>Show messages for the specified syslog identifier
 358         <replaceable>SYSLOG_IDENTIFIER</replaceable>.</para>
 359
 360         <para>This parameter can be specified multiple times.</para>
 361
 362         <xi:include href="version-info.xml" xpointer="v217"/></listitem>
 363       </varlistentry>
 364
 365       <varlistentry>
 366         <term><option>-T</option></term>
 367         <term><option>--exclude-identifier=<replaceable>SYSLOG_IDENTIFIER</replaceable></option></term>
 368
 369         <listitem><para>Exclude messages for the specified syslog identifier
 370         <replaceable>SYSLOG_IDENTIFIER</replaceable>.</para>
 371
 372         <para>This parameter can be specified multiple times.</para>
 373
 374         <xi:include href="version-info.xml" xpointer="v256"/></listitem>
 375       </varlistentry>
 376
 377       <varlistentry>
 378         <term><option>-p</option></term>
 379         <term><option>--priority=</option></term>
 380
 381         <listitem><para>Filter output by message priorities or priority ranges. Takes either a single numeric
 382         or textual log level (i.e. between 0/<literal>emerg</literal> and 7/<literal>debug</literal>), or a
 383         range of numeric/text log levels in the form FROM..TO. The log levels are the usual syslog log levels
 384         as documented in <citerefentry
 385         project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 386         i.e. <literal>emerg</literal> (0), <literal>alert</literal> (1), <literal>crit</literal> (2),
 387         <literal>err</literal> (3), <literal>warning</literal> (4), <literal>notice</literal> (5),
 388         <literal>info</literal> (6), <literal>debug</literal> (7). If a single log level is specified, all
 389         messages with this log level or a lower (hence more important) log level are shown. If a range is
 390         specified, all messages within the range are shown, including both the start and the end value of the
 391         range. This will add <literal>PRIORITY=</literal> matches for the specified
 392         priorities.</para>
 393
 394         <xi:include href="version-info.xml" xpointer="v188"/></listitem>
 395       </varlistentry>
 396
 397       <varlistentry>
 398         <term><option>--facility=</option></term>
 399
 400         <listitem><para>Filter output by syslog facility. Takes a comma-separated list of numbers or
 401         facility names. The names are the usual syslog facilities as documented in <citerefentry
 402         project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 403         <option>--facility=help</option> may be used to display a list of known facility names and exit.
 404         </para>
 405
 406         <xi:include href="version-info.xml" xpointer="v245"/></listitem>
 407       </varlistentry>
 408
 409       <varlistentry>
 410         <term><option>-g</option></term>
 411         <term><option>--grep=</option></term>
 412
 413         <listitem><para>Filter output to entries where the <varname>MESSAGE=</varname> field matches the
 414         specified regular expression. PERL-compatible regular expressions are used, see <citerefentry
 415         project='url'><refentrytitle
 416         url='http://pcre.org/current/doc/html/pcre2pattern.html'>pcre2pattern</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 417         for a detailed description of the syntax.</para>
 418
 419         <para>If the pattern is all lowercase, matching is case insensitive.  Otherwise, matching is case
 420         sensitive. This can be overridden with the <option>--case-sensitive</option> option, see
 421         below.</para>
 422
 423         <para>When used with <option>--lines=</option> (not prefixed with <literal>+</literal>),
 424         <option>--reverse</option> is implied.</para>
 425
 426         <xi:include href="version-info.xml" xpointer="v237"/></listitem>
 427       </varlistentry>
 428
 429       <varlistentry>
 430         <term><option>--case-sensitive<optional>=BOOLEAN</optional></option></term>
 431
 432         <listitem><para>Make pattern matching case sensitive or case insensitive.</para>
 433
 434         <xi:include href="version-info.xml" xpointer="v237"/></listitem>
 435       </varlistentry>
 436
 437       <varlistentry>
 438         <term><option>-k</option></term>
 439         <term><option>--dmesg</option></term>
 440
 441         <listitem><para>Show only kernel messages. This implies <option>-b</option> and adds the match
 442         <literal>_TRANSPORT=kernel</literal>.</para>
 443
 444         <xi:include href="version-info.xml" xpointer="v205"/></listitem>
 445       </varlistentry>
 446     </variablelist>
 447   </refsect1>
 448
 449   <refsect1>
 450     <title>Output Options</title>
 451
 452     <para>The following options control how journal records are printed:</para>
 453
 454     <variablelist>
 455       <varlistentry>
 456         <term><option>-o</option></term>
 457         <term><option>--output=</option></term>
 458
 459         <listitem><para>Controls the formatting of the journal entries that are shown. Takes one of the
 460         following options:</para>
 461
 462         <variablelist>
 463           <varlistentry>
 464             <term><option>short</option></term>
 465             <listitem><para>is the default and generates an output that is mostly identical to the
 466             formatting of classic syslog files, showing one line per journal entry.</para>
 467
 468             <xi:include href="version-info.xml" xpointer="v206"/></listitem>
 469           </varlistentry>
 470
 471           <varlistentry>
 472             <term><option>short-full</option></term>
 473             <listitem><para>is very similar, but shows timestamps in the format the
 474             <option>--since=</option> and <option>--until=</option> options accept. Unlike the timestamp
 475             information shown in <option>short</option> output mode this mode includes weekday, year and
 476             timezone information in the output, and is locale-independent.</para>
 477
 478             <xi:include href="version-info.xml" xpointer="v232"/></listitem>
 479           </varlistentry>
 480
 481           <varlistentry>
 482             <term><option>short-iso</option></term>
 483             <listitem><para>is very similar, but shows timestamps in the
 484             <ulink url="https://tools.ietf.org/html/rfc3339">RFC 3339</ulink> profile of ISO 8601.</para>
 485
 486             <xi:include href="version-info.xml" xpointer="v206"/></listitem>
 487           </varlistentry>
 488
 489           <varlistentry>
 490             <term><option>short-iso-precise</option></term>
 491             <listitem><para>as for <option>short-iso</option> but includes full microsecond
 492             precision.</para>
 493
 494             <xi:include href="version-info.xml" xpointer="v234"/></listitem>
 495           </varlistentry>
 496
 497           <varlistentry>
 498             <term><option>short-precise</option></term>
 499             <listitem><para>is very similar, but shows classic syslog timestamps with full microsecond
 500             precision.</para>
 501
 502             <xi:include href="version-info.xml" xpointer="v207"/></listitem>
 503           </varlistentry>
 504
 505           <varlistentry>
 506             <term><option>short-monotonic</option></term>
 507             <listitem><para>is very similar, but shows monotonic timestamps instead of wallclock
 508             timestamps.</para>
 509
 510             <xi:include href="version-info.xml" xpointer="v206"/></listitem>
 511           </varlistentry>
 512
 513           <varlistentry>
 514             <term><option>short-delta</option></term>
 515             <listitem><para>as for <option>short-monotonic</option> but includes the time difference
 516             to the previous entry.
 517             Maybe unreliable time differences are marked by a <literal>*</literal>.</para>
 518
 519             <xi:include href="version-info.xml" xpointer="v252"/></listitem>
 520           </varlistentry>
 521
 522           <varlistentry>
 523             <term><option>short-unix</option></term>
 524             <listitem><para>is very similar, but shows seconds passed since January 1st 1970 UTC instead of
 525             wallclock timestamps ("UNIX time"). The time is shown with microsecond accuracy.</para>
 526
 527             <xi:include href="version-info.xml" xpointer="v230"/></listitem>
 528           </varlistentry>
 529
 530           <varlistentry>
 531             <term><option>verbose</option></term>
 532             <listitem><para>shows the full-structured entry items with all fields.</para>
 533
 534             <xi:include href="version-info.xml" xpointer="v206"/></listitem>
 535           </varlistentry>
 536
 537           <varlistentry>
 538             <term><option>export</option></term>
 539             <listitem><para>serializes the journal into a binary (but mostly text-based) stream suitable
 540             for backups and network transfer (see <ulink
 541             url="https://systemd.io/JOURNAL_EXPORT_FORMATS#journal-export-format">Journal Export
 542             Format</ulink> for more information). To import the binary stream back into native journald
 543             format use
 544             <citerefentry><refentrytitle>systemd-journal-remote</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 545
 546             <xi:include href="version-info.xml" xpointer="v206"/></listitem>
 547           </varlistentry>
 548
 549           <varlistentry>
 550             <term><option>json</option></term>
 551             <listitem><para>formats entries as JSON objects, separated by newline characters (see <ulink
 552             url="https://systemd.io/JOURNAL_EXPORT_FORMATS#journal-json-format">Journal JSON Format</ulink>
 553             for more information). Field values are generally encoded as JSON strings, with three exceptions:
 554             <orderedlist>
 555               <listitem><para>Fields larger than 4096 bytes are encoded as <constant>null</constant>
 556               values. (This may be turned off by passing <option>--all</option>, but be aware that this may
 557               allocate overly long JSON objects.)</para></listitem>
 558
 559               <listitem><para>Journal entries permit non-unique fields within the same log entry. JSON does
 560               not allow non-unique fields within objects. Due to this, if a non-unique field is encountered a
 561               JSON array is used as field value, listing all field values as elements.</para></listitem>
 562
 563               <listitem><para>Fields containing non-printable or non-UTF8 bytes are encoded as arrays
 564               containing the raw bytes individually formatted as unsigned numbers.</para></listitem>
 565             </orderedlist>
 566
 567             Note that this encoding is reversible (with the exception of the size limit).</para>
 568
 569             <xi:include href="version-info.xml" xpointer="v206"/></listitem>
 570           </varlistentry>
 571
 572           <varlistentry>
 573             <term><option>json-pretty</option></term>
 574             <listitem><para>formats entries as JSON data structures, but formats them in multiple lines in
 575             order to make them more readable by humans.</para>
 576
 577             <xi:include href="version-info.xml" xpointer="v206"/></listitem>
 578           </varlistentry>
 579
 580           <varlistentry>
 581             <term><option>json-sse</option></term>
 582             <listitem><para>formats entries as JSON data structures, but wraps them in a format suitable for
 583             <ulink
 584             url="https://developer.mozilla.org/en-US/docs/Server-sent_events/Using_server-sent_events">Server-Sent
 585             Events</ulink>.</para>
 586
 587             <xi:include href="version-info.xml" xpointer="v206"/></listitem>
 588           </varlistentry>
 589
 590           <varlistentry>
 591             <term><option>json-seq</option></term>
 592             <listitem><para>formats entries as JSON data structures, but prefixes them with an ASCII Record
 593             Separator character (0x1E) and suffixes them with an ASCII Line Feed character (0x0A), in
 594             accordance with <ulink url="https://tools.ietf.org/html/rfc7464">JavaScript Object Notation
 595             (JSON) Text Sequences </ulink> (<literal>application/json-seq</literal>).</para>
 596
 597             <xi:include href="version-info.xml" xpointer="v240"/></listitem>
 598           </varlistentry>
 599
 600           <varlistentry>
 601             <term><option>cat</option></term>
 602             <listitem><para>generates a very terse output, only showing the actual message of each journal
 603             entry with no metadata, not even a timestamp. If combined with the
 604             <option>--output-fields=</option> option will output the listed fields for each log record,
 605             instead of the message.</para>
 606
 607             <xi:include href="version-info.xml" xpointer="v206"/></listitem>
 608           </varlistentry>
 609
 610           <varlistentry>
 611             <term><option>with-unit</option></term>
 612             <listitem><para>similar to <option>short-full</option>, but prefixes the unit and user unit names
 613             instead of the traditional syslog identifier. Useful when using templated instances, as it will
 614             include the arguments in the unit names.</para>
 615
 616             <xi:include href="version-info.xml" xpointer="v239"/></listitem>
 617           </varlistentry>
 618         </variablelist></listitem>
 619       </varlistentry>
 620
 621       <varlistentry>
 622         <term><option>--truncate-newline</option></term>
 623
 624         <listitem><para>Truncate each log message at the first newline character on output, so that only the
 625         first line of each message is displayed.</para>
 626
 627         <xi:include href="version-info.xml" xpointer="v254"/></listitem>
 628       </varlistentry>
 629
 630       <varlistentry>
 631         <term><option>--output-fields=</option></term>
 632
 633         <listitem><para>A comma separated list of the fields which should be included in the output. This
 634         has an effect only for the output modes which would normally show all fields
 635         (<option>verbose</option>, <option>export</option>, <option>json</option>,
 636         <option>json-pretty</option>, <option>json-sse</option> and <option>json-seq</option>), as well as
 637         on <option>cat</option>. For the former, the <literal>__CURSOR</literal>,
 638         <literal>__REALTIME_TIMESTAMP</literal>, <literal>__MONOTONIC_TIMESTAMP</literal>, and
 639         <literal>_BOOT_ID</literal> fields are always printed.</para>
 640
 641         <xi:include href="version-info.xml" xpointer="v236"/></listitem>
 642       </varlistentry>
 643
 644       <varlistentry>
 645         <term><option>-n</option></term>
 646         <term><option>--lines=</option></term>
 647
 648         <listitem><para>Show the most recent journal events and limit the number of events shown. The argument
 649         is a positive integer or <literal>all</literal> to disable the limit. Additionally, if the number is
 650         prefixed with <literal>+</literal>, the oldest journal events are used instead. The default value is
 651         10 if no argument is given.</para>
 652
 653         <para>If <option>--follow</option> is used, this option is implied. When not prefixed with <literal>+</literal>
 654         and used with <option>--grep=</option>, <option>--reverse</option> is implied.</para></listitem>
 655       </varlistentry>
 656
 657       <varlistentry>
 658         <term><option>-r</option></term>
 659         <term><option>--reverse</option></term>
 660
 661         <listitem><para>Reverse output so that the newest entries are displayed first.</para>
 662
 663         <xi:include href="version-info.xml" xpointer="v198"/></listitem>
 664       </varlistentry>
 665
 666       <varlistentry>
 667         <term><option>--show-cursor</option></term>
 668
 669         <listitem><para>The cursor is shown after the last entry after two dashes:</para>
 670         <programlisting>-- cursor: s=0639…</programlisting>
 671         <para>The format of the cursor is private and subject to change.</para>
 672
 673         <xi:include href="version-info.xml" xpointer="v209"/></listitem>
 674       </varlistentry>
 675
 676       <varlistentry>
 677         <term><option>--utc</option></term>
 678
 679         <listitem><para>Express time in Coordinated Universal Time (UTC).</para>
 680
 681         <xi:include href="version-info.xml" xpointer="v217"/></listitem>
 682       </varlistentry>
 683
 684       <varlistentry>
 685         <term><option>-x</option></term>
 686         <term><option>--catalog</option></term>
 687
 688         <listitem><para>Augment log lines with explanation texts from the message catalog. This will add
 689         explanatory help texts to log messages in the output where this is available. These short help texts
 690         will explain the context of an error or log event, possible solutions, as well as pointers to support
 691         forums, developer documentation, and any other relevant manuals. Note that help texts are not
 692         available for all messages, but only for selected ones. For more information on the message catalog,
 693         please refer to the <ulink url="https://www.freedesktop.org/wiki/Software/systemd/catalog">Message
 694         Catalog Developer Documentation</ulink>.</para>
 695
 696         <para>Note: when attaching <command>journalctl</command> output to bug reports, please do
 697         <emphasis>not</emphasis> use <option>-x</option>.</para>
 698
 699         <xi:include href="version-info.xml" xpointer="v196"/></listitem>
 700       </varlistentry>
 701
 702       <varlistentry>
 703         <term><option>--no-hostname</option></term>
 704
 705         <listitem><para>Don't show the hostname field of log messages originating from the local host. This
 706         switch has an effect only on the <option>short</option> family of output modes (see above).</para>
 707
 708         <para>Note: this option does not remove occurrences of the hostname from log entries themselves, so
 709         it does not prevent the hostname from being visible in the logs.</para>
 710
 711         <xi:include href="version-info.xml" xpointer="v230"/></listitem>
 712       </varlistentry>
 713
 714       <varlistentry>
 715         <term><option>--no-full</option></term>
 716         <term><option>--full</option></term>
 717         <term><option>-l</option></term>
 718
 719         <listitem><para>Ellipsize fields when they do not fit in available columns.  The default is to show
 720         full fields, allowing them to wrap or be truncated by the pager, if one is used.</para>
 721
 722         <para>The old options <option>-l</option>/<option>--full</option> are not useful anymore, except to
 723         undo <option>--no-full</option>.</para>
 724
 725         <xi:include href="version-info.xml" xpointer="v196"/></listitem>
 726       </varlistentry>
 727
 728       <varlistentry>
 729         <term><option>-a</option></term>
 730         <term><option>--all</option></term>
 731
 732         <listitem><para>Show all fields in full, even if they include unprintable characters or are very
 733         long. By default, fields with unprintable characters are abbreviated as "blob data". (Note that the
 734         pager may escape unprintable characters again.)</para></listitem>
 735       </varlistentry>
 736
 737       <varlistentry>
 738         <term><option>-f</option></term>
 739         <term><option>--follow</option></term>
 740
 741         <listitem><para>Show only the most recent journal entries, and continuously print new entries as
 742         they are appended to the journal.</para></listitem>
 743       </varlistentry>
 744
 745       <varlistentry>
 746         <term><option>--no-tail</option></term>
 747
 748         <listitem><para>Show all stored output lines, even in follow mode. Undoes the effect of
 749         <option>--lines=</option>.</para></listitem>
 750       </varlistentry>
 751
 752       <varlistentry>
 753         <term><option>-q</option></term>
 754         <term><option>--quiet</option></term>
 755
 756         <listitem><para>Suppresses all informational messages (i.e. "-- Journal begins at …", "-- Reboot
 757         --"), any warning messages regarding inaccessible system journals when run as a normal
 758         user.</para></listitem>
 759       </varlistentry>
 760     </variablelist>
 761   </refsect1>
 762
 763   <refsect1>
 764     <title>Pager Control Options</title>
 765
 766     <para>The following options control page support:</para>
 767
 768     <variablelist>
 769
 770       <xi:include href="standard-options.xml" xpointer="no-pager" />
 771
 772       <varlistentry>
 773         <term><option>-e</option></term>
 774         <term><option>--pager-end</option></term>
 775
 776         <listitem><para>Immediately jump to the end of the journal inside the implied pager tool. This
 777         implies <option>-n1000</option> to guarantee that the pager will not buffer logs of unbounded
 778         size. This may be overridden with an explicit <option>-n</option> with some other numeric value,
 779         while <option>-nall</option> will disable this cap.  Note that this option is only supported for
 780         the <citerefentry
 781         project='man-pages'><refentrytitle>less</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 782         pager.</para>
 783
 784         <xi:include href="version-info.xml" xpointer="v198"/></listitem>
 785       </varlistentry>
 786     </variablelist>
 787   </refsect1>
 788
 789   <refsect1>
 790     <title>Forward Secure Sealing (FSS) Options</title>
 791
 792     <para>The following options may be used together with the <option>--setup-keys</option> command described
 793     below:</para>
 794
 795     <variablelist>
 796       <varlistentry>
 797         <term><option>--interval=</option></term>
 798
 799         <listitem><para>Specifies the change interval for the sealing key when generating an FSS key pair
 800         with <option>--setup-keys</option>. Shorter intervals increase CPU consumption but shorten the time
 801         range of undetectable journal alterations. Defaults to 15min.</para>
 802
 803         <xi:include href="version-info.xml" xpointer="v189"/></listitem>
 804       </varlistentry>
 805
 806       <varlistentry>
 807         <term><option>--verify-key=</option></term>
 808
 809         <listitem><para>Specifies the FSS verification key to use for the <option>--verify</option>
 810         operation.</para>
 811
 812         <xi:include href="version-info.xml" xpointer="v189"/></listitem>
 813       </varlistentry>
 814
 815       <varlistentry>
 816         <term><option>--force</option></term>
 817
 818         <listitem><para>When <option>--setup-keys</option> is passed and Forward Secure Sealing (FSS) has
 819         already been configured, recreate FSS keys.</para>
 820
 821         <xi:include href="version-info.xml" xpointer="v206"/></listitem>
 822       </varlistentry>
 823     </variablelist>
 824   </refsect1>
 825
 826   <refsect1>
 827     <title>Commands</title>
 828
 829     <para>The following commands are understood. If none is specified the default is to display journal records:</para>
 830
 831     <variablelist>
 832       <varlistentry>
 833         <term><option>-N</option></term>
 834         <term><option>--fields</option></term>
 835
 836         <listitem><para>Print all field names currently used in all entries of the journal.</para>
 837
 838         <xi:include href="version-info.xml" xpointer="v229"/></listitem>
 839       </varlistentry>
 840
 841       <varlistentry>
 842         <term><option>-F</option></term>
 843         <term><option>--field=</option></term>
 844
 845         <listitem><para>Print all possible data values the specified field can take in all entries of the
 846         journal.</para>
 847
 848         <xi:include href="version-info.xml" xpointer="v195"/></listitem>
 849       </varlistentry>
 850
 851       <varlistentry>
 852         <term><option>--list-boots</option></term>
 853
 854         <listitem>
 855           <para>Show a tabular list of boot numbers (relative to the current boot), their IDs, and the
 856           timestamps of the first and last message pertaining to the boot. When specified with
 857           <option>-n/--lines=<optional>+</optional><replaceable>N</replaceable></option> option, only the
 858           first (when the number prefixed with <literal>+</literal>) or the last (without prefix)
 859           <replaceable>N</replaceable> entries will be shown. When specified with
 860           <option>-r/--reverse</option>, the list will be shown in the reverse order.</para>
 861
 862           <xi:include href="version-info.xml" xpointer="v209"/>
 863         </listitem>
 864       </varlistentry>
 865
 866       <varlistentry>
 867         <term><option>--disk-usage</option></term>
 868
 869         <listitem><para>Shows the current disk usage of all journal files. This shows the sum of the disk
 870         usage of all archived and active journal files.</para>
 871
 872         <xi:include href="version-info.xml" xpointer="v190"/></listitem>
 873       </varlistentry>
 874
 875       <varlistentry>
 876         <term><option>--vacuum-size=</option></term>
 877         <term><option>--vacuum-time=</option></term>
 878         <term><option>--vacuum-files=</option></term>
 879
 880         <listitem><para><option>--vacuum-size=</option> removes the oldest archived journal files until the
 881         disk space they use falls below the specified size. Accepts the usual <literal>K</literal>,
 882         <literal>M</literal>, <literal>G</literal> and <literal>T</literal> suffixes (to the base of
 883         1024).</para>
 884
 885         <para><option>--vacuum-time=</option> removes archived journal files older than the specified
 886         timespan. Accepts the usual <literal>s</literal> (default), <literal>m</literal>,
 887         <literal>h</literal>, <literal>days</literal>, <literal>weeks</literal>, <literal>months</literal>,
 888         and <literal>years</literal> suffixes, see
 889         <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
 890         details.</para>
 891
 892         <para><option>--vacuum-files=</option> leaves only the specified number of separate journal
 893         files.</para>
 894
 895         <para>Note that running <option>--vacuum-size=</option> has only an indirect effect on the output
 896         shown by <option>--disk-usage</option>, as the latter includes active journal files, while the
 897         vacuuming operation only operates on archived journal files. Similarly,
 898         <option>--vacuum-files=</option> might not actually reduce the number of journal files to below the
 899         specified number, as it will not remove active journal files.</para>
 900
 901         <para><option>--vacuum-size=</option>, <option>--vacuum-time=</option> and
 902         <option>--vacuum-files=</option> may be combined in a single invocation to enforce any combination of
 903         a size, a time and a number of files limit on the archived journal files. Specifying any of these
 904         three parameters as zero is equivalent to not enforcing the specific limit, and is thus
 905         redundant.</para>
 906
 907         <para>These three switches may also be combined with <option>--rotate</option> into one command. If
 908         so, all active files are rotated first, and the requested vacuuming operation is executed right
 909         after. The rotation has the effect that all currently active files are archived (and potentially new,
 910         empty journal files opened as replacement), and hence the vacuuming operation has the greatest effect
 911         as it can take all log data written so far into account.</para>
 912
 913         <xi:include href="version-info.xml" xpointer="v218"/></listitem>
 914       </varlistentry>
 915
 916       <varlistentry>
 917         <term><option>--verify</option></term>
 918
 919         <listitem><para>Check the journal file for internal consistency. If the file has been generated
 920         with FSS enabled and the FSS verification key has been specified with
 921         <option>--verify-key=</option>, authenticity of the journal file is verified.</para>
 922
 923         <xi:include href="version-info.xml" xpointer="v189"/></listitem>
 924       </varlistentry>
 925
 926       <varlistentry>
 927         <term><option>--sync</option></term>
 928
 929         <listitem><para>Asks the journal daemon to write all yet unwritten journal data to the backing file
 930         system and synchronize all journals. This call does not return until the synchronization operation
 931         is complete. This command guarantees that any log messages written before its invocation are safely
 932         stored on disk at the time it returns.</para>
 933
 934         <xi:include href="version-info.xml" xpointer="v228"/></listitem>
 935       </varlistentry>
 936
 937       <varlistentry>
 938         <term><option>--relinquish-var</option></term>
 939
 940         <listitem><para>Asks the journal daemon for the reverse operation to <option>--flush</option>: if
 941         requested the daemon will write further log data to <filename>/run/log/journal/</filename> and
 942         stops writing to <filename>/var/log/journal/</filename>. A subsequent call to
 943         <option>--flush</option> causes the log output to switch back to
 944         <filename>/var/log/journal/</filename>, see above.</para>
 945
 946         <xi:include href="version-info.xml" xpointer="v243"/></listitem>
 947       </varlistentry>
 948
 949       <varlistentry>
 950         <term><option>--smart-relinquish-var</option></term>
 951
 952         <listitem><para>Similar to <option>--relinquish-var</option>, but executes no operation if the root
 953         file system and <filename>/var/log/journal/</filename> reside on the same mount point. This operation
 954         is used during system shutdown in order to make the journal daemon stop writing data to
 955         <filename>/var/log/journal/</filename> in case that directory is located on a mount point that needs
 956         to be unmounted.</para>
 957
 958         <xi:include href="version-info.xml" xpointer="v243"/></listitem>
 959       </varlistentry>
 960
 961       <varlistentry>
 962         <term><option>--flush</option></term>
 963
 964         <listitem><para>Asks the journal daemon to flush any log data stored in
 965         <filename>/run/log/journal/</filename> into <filename>/var/log/journal/</filename>, if persistent
 966         storage is enabled. This call does not return until the operation is complete. Note that this call is
 967         idempotent: the data is only flushed from <filename>/run/log/journal/</filename> into
 968         <filename>/var/log/journal/</filename> once during system runtime (but see
 969         <option>--relinquish-var</option> below), and this command exits cleanly without executing any
 970         operation if this has already happened. This command effectively guarantees that all data is flushed
 971         to <filename>/var/log/journal/</filename> at the time it returns.</para>
 972
 973         <xi:include href="version-info.xml" xpointer="v217"/></listitem>
 974       </varlistentry>
 975
 976       <varlistentry>
 977         <term><option>--rotate</option></term>
 978
 979         <listitem><para>Asks the journal daemon to rotate journal files. This call does not return until
 980         the rotation operation is complete. Journal file rotation has the effect that all currently active
 981         journal files are marked as archived and renamed, so that they are never written to in future. New
 982         (empty) journal files are then created in their place. This operation may be combined with
 983         <option>--vacuum-size=</option>, <option>--vacuum-time=</option> and
 984         <option>--vacuum-file=</option> into a single command, see above.</para>
 985
 986         <xi:include href="version-info.xml" xpointer="v227"/></listitem>
 987       </varlistentry>
 988
 989       <varlistentry>
 990         <term><option>--header</option></term>
 991
 992         <listitem><para>Instead of showing journal contents, show internal header information of the
 993         journal fields accessed.</para>
 994
 995         <para>This option is particularly useful when trying to identify out-of-order journal entries, as
 996         happens for example when the machine is booted with the wrong system time.</para>
 997
 998         <xi:include href="version-info.xml" xpointer="v187"/></listitem>
 999       </varlistentry>
1000
1001       <varlistentry>
1002         <term><option>--list-catalog <optional><replaceable>128-bit-ID…</replaceable></optional></option></term>
1003
1004         <listitem><para>List the contents of the message catalog as a table of message IDs, plus their
1005         short description strings.</para>
1006
1007         <para>If any <replaceable>128-bit-ID</replaceable>s are specified, only those entries are
1008         shown.</para>
1009
1010         <xi:include href="version-info.xml" xpointer="v196"/></listitem>
1011       </varlistentry>
1012
1013       <varlistentry>
1014         <term><option>--dump-catalog <optional><replaceable>128-bit-ID…</replaceable></optional></option></term>
1015
1016         <listitem><para>Show the contents of the message catalog, with entries separated by a line
1017         consisting of two dashes and the ID (the format is the same as <filename>.catalog</filename>
1018         files).</para>
1019
1020         <para>If any <replaceable>128-bit-ID</replaceable>s are specified, only those entries are
1021         shown.</para>
1022
1023         <xi:include href="version-info.xml" xpointer="v199"/></listitem>
1024       </varlistentry>
1025
1026       <varlistentry>
1027         <term><option>--update-catalog</option></term>
1028
1029         <listitem><para>Update the message catalog index. This command needs to be executed each time new
1030         catalog files are installed, removed, or updated to rebuild the binary catalog
1031         index.</para>
1032
1033         <xi:include href="version-info.xml" xpointer="v196"/></listitem>
1034       </varlistentry>
1035
1036       <varlistentry>
1037         <term><option>--setup-keys</option></term>
1038
1039         <listitem><para>Instead of showing journal contents, generate a new key pair for Forward Secure
1040         Sealing (FSS). This will generate a sealing key and a verification key. The sealing key is stored in
1041         the journal data directory and shall remain on the host. The verification key should be stored
1042         externally. Refer to the <option>Seal=</option> option in
1043         <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
1044         information on Forward Secure Sealing and for a link to a refereed scholarly paper detailing the
1045         cryptographic theory it is based on.</para>
1046
1047         <xi:include href="version-info.xml" xpointer="v189"/></listitem>
1048       </varlistentry>
1049
1050       <xi:include href="standard-options.xml" xpointer="help" />
1051       <xi:include href="standard-options.xml" xpointer="version" />
1052     </variablelist>
1053   </refsect1>
1054
1055   <refsect1>
1056     <title>Exit status</title>
1057
1058     <para>On success, 0 is returned; otherwise, a non-zero failure code is returned.</para>
1059   </refsect1>
1060
1061   <xi:include href="common-variables.xml" />
1062
1063   <refsect1>
1064     <title>Examples</title>
1065
1066     <para>Without arguments, all collected logs are shown unfiltered:</para>
1067
1068     <programlisting>journalctl</programlisting>
1069
1070     <para>With one match specified, all entries with a field matching the expression are shown:</para>
1071
1072     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service
1073 journalctl _SYSTEMD_CGROUP=/user.slice/user-42.slice/session-c1.scope</programlisting>
1074
1075     <para>If two different fields are matched, only entries matching both expressions at the same time are
1076     shown:</para>
1077
1078     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097</programlisting>
1079
1080     <para>If two matches refer to the same field, all entries matching either expression are shown:</para>
1081
1082     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _SYSTEMD_UNIT=dbus.service</programlisting>
1083
1084     <para>If the separator <literal>+</literal> is used, two expressions may be combined in a logical OR. The
1085     following will show all messages from the Avahi service process with the PID 28097 plus all messages from
1086     the D-Bus service (from any of its processes):</para>
1087
1088     <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097 + _SYSTEMD_UNIT=dbus.service</programlisting>
1089
1090     <para>To show all fields emitted <emphasis>by</emphasis> a unit and <emphasis>about</emphasis> the unit,
1091     option <option>-u</option>/<option>--unit=</option> should be used. <command>journalctl -u
1092     <replaceable>name</replaceable></command> expands to a complex filter similar to
1093
1094     <programlisting>_SYSTEMD_UNIT=<replaceable>name</replaceable>.service
1095   + UNIT=<replaceable>name</replaceable>.service _PID=1
1096   + OBJECT_SYSTEMD_UNIT=<replaceable>name</replaceable>.service _UID=0
1097   + COREDUMP_UNIT=<replaceable>name</replaceable>.service _UID=0 MESSAGE_ID=fc2e22bc6ee647b6b90729ab34a250b1</programlisting>
1098
1099     (see
1100     <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1101     for an explanation of those patterns).</para>
1102
1103     <para>Show all logs generated by the D-Bus executable:</para>
1104
1105     <programlisting>journalctl /usr/bin/dbus-daemon</programlisting>
1106
1107     <para>Show all kernel logs from previous boot:</para>
1108
1109     <programlisting>journalctl -k -b -1</programlisting>
1110
1111     <para>Show a live log display from a system service <filename>apache.service</filename>:</para>
1112
1113     <programlisting>journalctl -f -u apache</programlisting>
1114   </refsect1>
1115
1116   <refsect1>
1117     <title>See Also</title>
1118     <para><simplelist type="inline">
1119       <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
1120       <member><citerefentry><refentrytitle>systemd-cat</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
1121       <member><citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
1122       <member><citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
1123       <member><citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
1124       <member><citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
1125       <member><citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
1126       <member><citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
1127       <member><citerefentry><refentrytitle>systemd-journal-remote.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
1128       <member><citerefentry><refentrytitle>systemd-journal-upload.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
1129     </simplelist></para>
1130   </refsect1>
1131 </refentry>