man/journalctl.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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   8   Copyright 2012 Lennart Poettering
   9
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  23
  24 <refentry id="journalctl">
  25
  26         <refentryinfo>
  27                 <title>journalctl</title>
  28                 <productname>systemd</productname>
  29
  30                 <authorgroup>
  31                         <author>
  32                                 <contrib>Developer</contrib>
  33                                 <firstname>Lennart</firstname>
  34                                 <surname>Poettering</surname>
  35                                 <email>lennart@poettering.net</email>
  36                         </author>
  37                 </authorgroup>
  38         </refentryinfo>
  39
  40         <refmeta>
  41                 <refentrytitle>journalctl</refentrytitle>
  42                 <manvolnum>1</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>journalctl</refname>
  47                 <refpurpose>Query the systemd journal</refpurpose>
  48         </refnamediv>
  49
  50         <refsynopsisdiv>
  51                 <cmdsynopsis>
  52                         <command>journalctl <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt" rep="repeat">MATCHES</arg></command>
  53                 </cmdsynopsis>
  54         </refsynopsisdiv>
  55
  56         <refsect1>
  57                 <title>Description</title>
  58
  59                 <para><command>journalctl</command> may be used to
  60                 query the contents of the
  61                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  62                 journal as written by
  63                 <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
  64
  65                 <para>If called without parameter it will show the full
  66                 contents of the journal, starting with the oldest
  67                 entry collected.</para>
  68
  69                 <para>If one or more match arguments are passed the
  70                 output is filtered accordingly. A match is in the
  71                 format <literal>FIELD=VALUE</literal>,
  72                 e.g. <literal>_SYSTEMD_UNIT=httpd.service</literal>,
  73                 referring to the components of a structured journal
  74                 entry. See
  75                 <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
  76                 for a list of well-known fields. If multiple matches
  77                 are specified matching different fields the log
  78                 entries are filtered by both, i.e. the resulting output
  79                 will show only entries matching all the specified
  80                 matches of this kind. If two matches apply to the same
  81                 field, then they are automatically matched as
  82                 alternatives, i.e. the resulting output will show
  83                 entries matching any of the specified matches for the
  84                 same field. Finally, if the character
  85                 "<literal>+</literal>" appears as separate word on the
  86                 command line all matches before and after are combined
  87                 in a disjunction (i.e. logical OR).</para>
  88
  89                 <para>As shortcuts for a few types of field/value
  90                 matches file paths may be specified. If a file path
  91                 refers to an executable file, this is equivalent to an
  92                 <literal>_EXE=</literal> match for the canonicalized
  93                 binary path. Similar, if a path refers to a device
  94                 node, this is equivalent to a
  95                 <literal>_KERNEL_DEVICE=</literal> match for the
  96                 device.</para>
  97
  98                 <para>Output is interleaved from all accessible
  99                 journal files, whether they are rotated or currently
 100                 being written, and regardless whether they belong to the
 101                 system itself or are accessible user journals.</para>
 102
 103                 <para>All users are granted access to their private
 104                 per-user journals. However, by default only root and
 105                 users who are members of the <literal>adm</literal>
 106                 group get access to the system journal and the
 107                 journals of other users.</para>
 108         </refsect1>
 109
 110         <refsect1>
 111                 <title>Options</title>
 112
 113                 <para>The following options are understood:</para>
 114
 115                 <variablelist>
 116                         <varlistentry>
 117                                 <term><option>--help</option></term>
 118                                 <term><option>-h</option></term>
 119
 120                                 <listitem><para>Prints a short help
 121                                 text and exits.</para></listitem>
 122                         </varlistentry>
 123
 124                         <varlistentry>
 125                                 <term><option>--version</option></term>
 126
 127                                 <listitem><para>Prints a short version
 128                                 string and exits.</para></listitem>
 129                         </varlistentry>
 130
 131                         <varlistentry>
 132                                 <term><option>--no-pager</option></term>
 133
 134                                 <listitem><para>Do not pipe output into a
 135                                 pager.</para></listitem>
 136                         </varlistentry>
 137
 138                         <varlistentry>
 139                                 <term><option>--all</option></term>
 140                                 <term><option>-a</option></term>
 141
 142                                 <listitem><para>Show all fields in
 143                                 full, even if they include unprintable
 144                                 characters or are very
 145                                 long.</para></listitem>
 146                         </varlistentry>
 147
 148                         <varlistentry>
 149                                 <term><option>--follow</option></term>
 150                                 <term><option>-f</option></term>
 151
 152                                 <listitem><para>Show only the most recent
 153                                 journal entries, and continuously print
 154                                 new entries as they are appended to
 155                                 the journal.</para></listitem>
 156                         </varlistentry>
 157
 158                         <varlistentry>
 159                                 <term><option>--lines=</option></term>
 160                                 <term><option>-n</option></term>
 161
 162                                 <listitem><para>Controls the number of
 163                                 journal lines to show, counting from
 164                                 the most recent ones. The argument is
 165                                 optional, and if specified is a
 166                                 positive integer. If not specified and
 167                                 in follow mode defaults to 10. If this
 168                                 option is not passed and follow mode
 169                                 is not enabled, how many lines are
 170                                 shown is not
 171                                 limited.</para></listitem>
 172                         </varlistentry>
 173
 174                         <varlistentry>
 175                                 <term><option>--no-tail</option></term>
 176
 177                                 <listitem><para>Show all stored output
 178                                 lines, even in follow mode. Undoes the
 179                                 effect of
 180                                 <option>--lines=</option>.</para></listitem>
 181                         </varlistentry>
 182
 183                         <varlistentry>
 184                                 <term><option>--output=</option></term>
 185                                 <term><option>-o</option></term>
 186
 187                                 <listitem><para>Controls the
 188                                 formatting of the journal entries that
 189                                 are shown. Takes one of
 190                                 <literal>short</literal>,
 191                                 <literal>short-monotonic</literal>,
 192                                 <literal>verbose</literal>,
 193                                 <literal>export</literal>,
 194                                 <literal>json</literal>,
 195                                 <literal>json-pretty</literal>,
 196                                 <literal>cat</literal>. <literal>short</literal>
 197                                 is the default and generates an output
 198                                 that is mostly identical to the
 199                                 formatting of classic syslog log
 200                                 files, showing one line per journal
 201                                 entry. <literal>short-monotonic</literal>
 202                                 is very similar but shows monotonic
 203                                 timestamps instead of wallclock
 204                                 timestamps. <literal>verbose</literal>
 205                                 shows the full structured entry items
 206                                 with all
 207                                 fields. <literal>export</literal>
 208                                 serializes the journal into a binary
 209                                 (but mostly text-based) stream
 210                                 suitable for backups and network
 211                                 transfer (see <ulink
 212                                 url="http://www.freedesktop.org/wiki/Software/systemd/export">Journal
 213                                 Export Format</ulink> for more
 214                                 information). <literal>json</literal>
 215                                 formats entries as JSON data
 216                                 structures, one per
 217                                 line. <literal>json-pretty</literal>
 218                                 also formats entries as JSON data
 219                                 structures, but formats them in
 220                                 multiple lines in order to make them
 221                                 more readable for
 222                                 humans. <literal>cat</literal>
 223                                 generates a very terse output only
 224                                 showing the actual message of each
 225                                 journal entry with no meta data, not
 226                                 even a timestamp.</para></listitem>
 227                         </varlistentry>
 228
 229                         <varlistentry>
 230                                 <term><option>--quiet</option></term>
 231                                 <term><option>-q</option></term>
 232
 233                                 <listitem><para>Suppresses any warning
 234                                 message regarding inaccessible system
 235                                 journals when run as normal
 236                                 user.</para></listitem>
 237                         </varlistentry>
 238
 239                         <varlistentry>
 240                                 <term><option>--merge</option></term>
 241                                 <term><option>-m</option></term>
 242
 243                                 <listitem><para>Show entries
 244                                 interleaved from all available
 245                                 journals, including remote
 246                                 ones.</para></listitem>
 247                         </varlistentry>
 248
 249                         <varlistentry>
 250                                 <term><option>--this-boot</option></term>
 251                                 <term><option>-b</option></term>
 252
 253                                 <listitem><para>Show data only from
 254                                 current boot.</para></listitem>
 255                         </varlistentry>
 256
 257                         <varlistentry>
 258                                 <term><option>--directory=</option></term>
 259                                 <term><option>-D</option></term>
 260
 261                                 <listitem><para>Takes an absolute
 262                                 directory path as argument. If
 263                                 specified journalctl will operate on the
 264                                 specified journal directory instead of
 265                                 the default runtime and system journal
 266                                 paths.</para></listitem>
 267                         </varlistentry>
 268
 269                         <varlistentry>
 270                                 <term><option>-p</option></term>
 271                                 <term><option>--priority=</option></term>
 272
 273                                 <listitem><para>Filter output by
 274                                 message priorities or priority
 275                                 ranges. Takes either a single numeric
 276                                 or textual log level (i.e. between
 277                                 0/<literal>emerg</literal> and
 278                                 7/<literal>debug</literal>), or a
 279                                 range of numeric/text log levels in
 280                                 the form FROM..TO. The log levels are
 281                                 the usual syslog log levels as
 282                                 documented in
 283                                 <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 284                                 i.e. <literal>emerg</literal> (0),
 285                                 <literal>alert</literal> (1),
 286                                 <literal>crit</literal> (2),
 287                                 <literal>err</literal> (3),
 288                                 <literal>warning</literal> (4),
 289                                 <literal>notice</literal> (5),
 290                                 <literal>info</literal> (6),
 291                                 <literal>debug</literal> (7). If a
 292                                 single log level is specified all
 293                                 messages with this log level or a
 294                                 lower (hence more important) log level
 295                                 are shown. If a range is specified all
 296                                 messages within the range are shown,
 297                                 including both the start and the end
 298                                 value of the range.</para></listitem>
 299                         </varlistentry>
 300
 301                         <varlistentry>
 302                                 <term><option>--new-id128</option></term>
 303
 304                                 <listitem><para>Instead of showing
 305                                 journal contents generate a new 128
 306                                 bit ID suitable for identifying
 307                                 messages. This is intended for usage
 308                                 by developers who need a new
 309                                 identifier for a new message they
 310                                 introduce and want to make
 311                                 recognizable. Will print the new ID in
 312                                 three different formats which can be
 313                                 copied into source code or
 314                                 similar.</para></listitem>
 315                         </varlistentry>
 316
 317                         <varlistentry>
 318                                 <term><option>--header</option></term>
 319
 320                                 <listitem><para>Instead of showing
 321                                 journal contents show internal header
 322                                 information of the journal fields
 323                                 accessed.</para></listitem>
 324                         </varlistentry>
 325
 326                         <varlistentry>
 327                                 <term><option>--disk-usage</option></term>
 328
 329                                 <listitem><para>Shows the current disk
 330                                 usage of all
 331                                 journal files.</para></listitem>
 332                         </varlistentry>
 333
 334                         <varlistentry>
 335                                 <term><option>--setup-keys</option></term>
 336
 337                                 <listitem><para>Instead of showing
 338                                 journal contents generate a new key
 339                                 pair for Forward Secure Sealing
 340                                 (FSS). This will generate a sealing
 341                                 key and a verification key. The
 342                                 sealing key is stored in the journal
 343                                 data directory and shall remain on the
 344                                 host. The verification key should be
 345                                 stored externally.</para></listitem>
 346                         </varlistentry>
 347
 348                         <varlistentry>
 349                                 <term><option>--interval=</option></term>
 350
 351                                 <listitem><para>Specifies the change
 352                                 interval for the sealing key, when
 353                                 generating an FSS key pair with
 354                                 <option>--setup-keys</option>. Shorter
 355                                 intervals increase CPU consumption but
 356                                 shorten the time range of
 357                                 undetectable journal
 358                                 alterations. Defaults to
 359                                 15min.</para></listitem>
 360                         </varlistentry>
 361
 362                         <varlistentry>
 363                                 <term><option>--verify</option></term>
 364
 365                                 <listitem><para>Check the journal file
 366                                 for internal consistency. If the
 367                                 file has been generated with FSS
 368                                 enabled, and the FSS verification key
 369                                 has been specified with
 370                                 <option>--verify-key=</option>
 371                                 authenticity of the journal file is
 372                                 verified.</para></listitem>
 373                         </varlistentry>
 374
 375                         <varlistentry>
 376                                 <term><option>--verify-key=</option></term>
 377
 378                                 <listitem><para>Specifies the FSS
 379                                 verification key to use for the
 380                                 <option>--verify</option>
 381                                 operation.</para></listitem>
 382                         </varlistentry>
 383
 384                 </variablelist>
 385         </refsect1>
 386
 387         <refsect1>
 388                 <title>Exit status</title>
 389
 390                 <para>On success 0 is returned, a non-zero failure
 391                 code otherwise.</para>
 392         </refsect1>
 393
 394         <refsect1>
 395                 <title>Environment</title>
 396
 397                 <variablelist>
 398                         <varlistentry>
 399                                 <term><varname>$SYSTEMD_PAGER</varname></term>
 400                                 <listitem><para>Pager to use when
 401                                 <option>--no-pager</option> is not given;
 402                                 overrides <varname>$PAGER</varname>.  Setting
 403                                 this to an empty string or the value
 404                                 <literal>cat</literal> is equivalent to passing
 405                                 <option>--no-pager</option>.</para></listitem>
 406                         </varlistentry>
 407                 </variablelist>
 408         </refsect1>
 409
 410         <refsect1>
 411                 <title>Examples</title>
 412
 413                 <para>Without arguments all collected logs are shown
 414                 unfiltered:</para>
 415
 416                 <programlisting>journalctl</programlisting>
 417
 418                 <para>With one match specified all entries with a field matching the expression are shown:</para>
 419
 420                 <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service</programlisting>
 421
 422                 <para>If two different fields are matched only entries matching both expressions at the same time are shown:</para>
 423
 424                 <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097</programlisting>
 425
 426                 <para>If two matches refer to the same field all entries matching either expression are shown:</para>
 427
 428                 <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _SYSTEMD_UNIT=dbus.service</programlisting>
 429
 430                 <para>If the separator "<literal>+</literal>" is used
 431                 two expressions may be combined in a logical OR. The
 432                 following will show all messages from the Avahi
 433                 service process with the PID 28097 plus all messages
 434                 from the D-Bus service (from any of its
 435                 processes):</para>
 436
 437                 <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097 + _SYSTEMD_UNIT=dbus.service</programlisting>
 438
 439                 <para>Show all logs generated by the D-Bus executable:</para>
 440
 441                 <programlisting>journalctl /usr/bin/dbus-daemon</programlisting>
 442
 443                 <para>Show all logs of the kernel device node <filename>/dev/sda</filename>:</para>
 444
 445                 <programlisting>journalctl /dev/sda</programlisting>
 446
 447         </refsect1>
 448
 449         <refsect1>
 450                 <title>See Also</title>
 451                 <para>
 452                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 453                         <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 454                         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 455                         <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 456                         <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 457                 </para>
 458         </refsect1>
 459
 460 </refentry>