man/journalctl.xml

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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 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>Output is interleaved from all accessible
  90                 journal files, whether they are rotated or currently
  91                 being written, and regardless whether they belong to the
  92                 system itself or are accessible user journals.</para>
  93
  94                 <para>All users are granted access to their private
  95                 per-user journals. However, by default only root and
  96                 users who are members of the <literal>adm</literal>
  97                 group get access to the system journal and the
  98                 journals of other users.</para>
  99         </refsect1>
 100
 101         <refsect1>
 102                 <title>Options</title>
 103
 104                 <para>The following options are understood:</para>
 105
 106                 <variablelist>
 107                         <varlistentry>
 108                                 <term><option>--help</option></term>
 109                                 <term><option>-h</option></term>
 110
 111                                 <listitem><para>Prints a short help
 112                                 text and exits.</para></listitem>
 113                         </varlistentry>
 114
 115                         <varlistentry>
 116                                 <term><option>--version</option></term>
 117
 118                                 <listitem><para>Prints a short version
 119                                 string and exits.</para></listitem>
 120                         </varlistentry>
 121
 122                         <varlistentry>
 123                                 <term><option>--no-pager</option></term>
 124
 125                                 <listitem><para>Do not pipe output into a
 126                                 pager.</para></listitem>
 127                         </varlistentry>
 128
 129                         <varlistentry>
 130                                 <term><option>--all</option></term>
 131                                 <term><option>-a</option></term>
 132
 133                                 <listitem><para>Show all fields in
 134                                 full, even if they include unprintable
 135                                 characters or are very
 136                                 long.</para></listitem>
 137                         </varlistentry>
 138
 139                         <varlistentry>
 140                                 <term><option>--follow</option></term>
 141                                 <term><option>-f</option></term>
 142
 143                                 <listitem><para>Show only most recent
 144                                 journal entries, and continuously print
 145                                 new entries as they are appended to
 146                                 the journal.</para></listitem>
 147                         </varlistentry>
 148
 149                         <varlistentry>
 150                                 <term><option>--lines=</option></term>
 151                                 <term><option>-n</option></term>
 152
 153                                 <listitem><para>Controls the number of
 154                                 journal lines to show, counting from
 155                                 the most recent ones. Takes a positive
 156                                 integer argument. In follow mode
 157                                 defaults to 10, otherwise is unset
 158                                 thus not limiting how many lines are
 159                                 shown.</para></listitem>
 160                         </varlistentry>
 161
 162                         <varlistentry>
 163                                 <term><option>--no-tail</option></term>
 164
 165                                 <listitem><para>Show all stored output
 166                                 lines, even in follow mode. Undoes the
 167                                 effect of
 168                                 <option>--lines=</option>.</para></listitem>
 169                         </varlistentry>
 170
 171                         <varlistentry>
 172                                 <term><option>--output=</option></term>
 173                                 <term><option>-o</option></term>
 174
 175                                 <listitem><para>Controls the
 176                                 formatting of the journal entries that are
 177                                 shown. Takes one of
 178                                 <literal>short</literal>,
 179                                 <literal>short-monotonic</literal>,
 180                                 <literal>verbose</literal>,
 181                                 <literal>export</literal>,
 182                                 <literal>json</literal>,
 183                                 <literal>cat</literal>. <literal>short</literal>
 184                                 is the default and generates an output
 185                                 that is mostly identical to the
 186                                 formatting of classic syslog log
 187                                 files, showing one line per journal
 188                                 entry. <literal>short-monotonic</literal>
 189                                 is very similar but shows monotonic
 190                                 timestamps instead of wallclock
 191                                 timestamps. <literal>verbose</literal>
 192                                 shows the full structured entry items
 193                                 with all
 194                                 fields. <literal>export</literal>
 195                                 serializes the journal into a binary
 196                                 (but mostly text-based) stream
 197                                 suitable for backups and network
 198                                 transfer. <literal>json</literal>
 199                                 formats entries as JSON data
 200                                 structures. <literal>cat</literal>
 201                                 generates a very terse output only
 202                                 showing the actual message of each
 203                                 journal entry with no meta data, not
 204                                 even a timestamp.</para></listitem>
 205                         </varlistentry>
 206
 207                         <varlistentry>
 208                                 <term><option>--quiet</option></term>
 209                                 <term><option>-q</option></term>
 210
 211                                 <listitem><para>Suppresses any warning
 212                                 message regarding inaccessible system
 213                                 journals when run as normal
 214                                 user.</para></listitem>
 215                         </varlistentry>
 216
 217                         <varlistentry>
 218                                 <term><option>--local</option></term>
 219                                 <term><option>-l</option></term>
 220
 221                                 <listitem><para>Show only locally
 222                                 generated messages.</para></listitem>
 223                         </varlistentry>
 224
 225                         <varlistentry>
 226                                 <term><option>--this-boot</option></term>
 227                                 <term><option>-b</option></term>
 228
 229                                 <listitem><para>Show data only from
 230                                 current boot.</para></listitem>
 231                         </varlistentry>
 232
 233                         <varlistentry>
 234                                 <term><option>--directory=</option></term>
 235                                 <term><option>-D</option></term>
 236
 237                                 <listitem><para>Takes an absolute
 238                                 directory path as argument. If
 239                                 specified will operate on the
 240                                 specified journal directory instead of
 241                                 the default runtime and system journal
 242                                 paths.</para></listitem>
 243                         </varlistentry>
 244
 245                         <varlistentry>
 246                                 <term><option>--new-id128</option></term>
 247
 248                                 <listitem><para>Instead of showing
 249                                 journal contents generate a new 128
 250                                 bit ID suitable for identifying
 251                                 messages. This is intended for usage
 252                                 by developers who need a new
 253                                 identifier for a new message they
 254                                 introduce and want to make
 255                                 recognizable. Will print the new ID in
 256                                 three different formats which can be
 257                                 copied into source code or
 258                                 similar.</para></listitem>
 259                         </varlistentry>
 260
 261                 </variablelist>
 262         </refsect1>
 263
 264         <refsect1>
 265                 <title>Exit status</title>
 266
 267                 <para>On success 0 is returned, a non-zero failure
 268                 code otherwise.</para>
 269         </refsect1>
 270
 271         <refsect1>
 272                 <title>Environment</title>
 273
 274                 <variablelist>
 275                         <varlistentry>
 276                                 <term><varname>$SYSTEMD_PAGER</varname></term>
 277                                 <listitem><para>Pager to use when
 278                                 <option>--no-pager</option> is not given;
 279                                 overrides <varname>$PAGER</varname>.  Setting
 280                                 this to an empty string or the value
 281                                 <literal>cat</literal> is equivalent to passing
 282                                 <option>--no-pager</option>.</para></listitem>
 283                         </varlistentry>
 284                 </variablelist>
 285         </refsect1>
 286
 287         <refsect1>
 288                 <title>Examples</title>
 289
 290                 <para>Without arguments all collected logs are shown
 291                 unfiltered:</para>
 292
 293                 <programlisting>journalctl</programlisting>
 294
 295                 <para>With one match specified all entries with a field matching the expression are shown:</para>
 296
 297                 <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service</programlisting>
 298
 299                 <para>If two different fields are matched only entries matching both expressions at the same time are shown:</para>
 300
 301                 <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097</programlisting>
 302
 303                 <para>If two matches refer to the same field all entries matching either expression are shown:</para>
 304
 305                 <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _SYSTEMD_UNIT=dbus.service</programlisting>
 306
 307                 <para>If the separator "<literal>+</literal>" is used
 308                 two expression may be combined in a logical OR. The
 309                 following will show all messages from the Avahi
 310                 service process with the PID 28097 plus all messages
 311                 from the D-Bus service (from any of its
 312                 processes):</para>
 313
 314                 <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097 + _SYSTEMD_UNIT=dbus.service</programlisting>
 315
 316         </refsect1>
 317
 318         <refsect1>
 319                 <title>See Also</title>
 320                 <para>
 321                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 322                         <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 323                         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 324                         <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 325                         <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 326                 </para>
 327         </refsect1>
 328
 329 </refentry>