eudev/man/journalctl.xml
2012-10-25 01:24:44 +02:00

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<refentry id="journalctl">
<refentryinfo>
<title>journalctl</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>journalctl</refentrytitle>
<manvolnum>1</manvolnum>
</refmeta>
<refnamediv>
<refname>journalctl</refname>
<refpurpose>Query the systemd journal</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>journalctl <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt" rep="repeat">MATCHES</arg></command>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><command>journalctl</command> may be used to
query the contents of the
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
journal as written by
<citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
<para>If called without parameter it will show the full
contents of the journal, starting with the oldest
entry collected.</para>
<para>If one or more match arguments are passed the
output is filtered accordingly. A match is in the
format <literal>FIELD=VALUE</literal>,
e.g. <literal>_SYSTEMD_UNIT=httpd.service</literal>,
referring to the components of a structured journal
entry. See
<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
for a list of well-known fields. If multiple matches
are specified matching different fields the log
entries are filtered by both, i.e. the resulting output
will show only entries matching all the specified
matches of this kind. If two matches apply to the same
field, then they are automatically matched as
alternatives, i.e. the resulting output will show
entries matching any of the specified matches for the
same field. Finally, if the character
"<literal>+</literal>" appears as separate word on the
command line all matches before and after are combined
in a disjunction (i.e. logical OR).</para>
<para>As shortcuts for a few types of field/value
matches file paths may be specified. If a file path
refers to an executable file, this is equivalent to an
<literal>_EXE=</literal> match for the canonicalized
binary path. Similar, if a path refers to a device
node, this is equivalent to a
<literal>_KERNEL_DEVICE=</literal> match for the
device.</para>
<para>Output is interleaved from all accessible
journal files, whether they are rotated or currently
being written, and regardless whether they belong to the
system itself or are accessible user journals.</para>
<para>All users are granted access to their private
per-user journals. However, by default only root and
users who are members of the <literal>adm</literal>
group get access to the system journal and the
journals of other users.</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>The following options are understood:</para>
<variablelist>
<varlistentry>
<term><option>--help</option></term>
<term><option>-h</option></term>
<listitem><para>Prints a short help
text and exits.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--version</option></term>
<listitem><para>Prints a short version
string and exits.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--no-pager</option></term>
<listitem><para>Do not pipe output into a
pager.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--all</option></term>
<term><option>-a</option></term>
<listitem><para>Show all fields in
full, even if they include unprintable
characters or are very
long.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--follow</option></term>
<term><option>-f</option></term>
<listitem><para>Show only the most recent
journal entries, and continuously print
new entries as they are appended to
the journal.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--lines=</option></term>
<term><option>-n</option></term>
<listitem><para>Show the most recent
journal events and limit the number of
events shown. If
<option>--follow</option> is used,
this option is implied. The argument,
a positive integer, is optional, and
defaults to 10. </para></listitem>
</varlistentry>
<varlistentry>
<term><option>--no-tail</option></term>
<listitem><para>Show all stored output
lines, even in follow mode. Undoes the
effect of
<option>--lines=</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--output=</option></term>
<term><option>-o</option></term>
<listitem><para>Controls the
formatting of the journal entries that
are shown. Takes one of
<literal>short</literal>,
<literal>short-monotonic</literal>,
<literal>verbose</literal>,
<literal>export</literal>,
<literal>json</literal>,
<literal>json-pretty</literal>,
<literal>json-sse</literal>,
<literal>cat</literal>. <literal>short</literal>
is the default and generates an output
that is mostly identical to the
formatting of classic syslog log
files, showing one line per journal
entry. <literal>short-monotonic</literal>
is very similar but shows monotonic
timestamps instead of wallclock
timestamps. <literal>verbose</literal>
shows the full structured entry items
with all
fields. <literal>export</literal>
serializes the journal into a binary
(but mostly text-based) stream
suitable for backups and network
transfer (see <ulink
url="http://www.freedesktop.org/wiki/Software/systemd/export">Journal
Export Format</ulink> for more
information). <literal>json</literal>
formats entries as JSON data
structures, one per
line (see <ulink
url="http://www.freedesktop.org/wiki/Software/systemd/json">Journal
JSON Format</ulink> for more
information). <literal>json-pretty</literal>
also formats entries as JSON data
structures, but formats them in
multiple lines in order to make them
more readable for
humans. <literal>json-sse</literal>
also formats entries as JSON data
structures, but wraps them in a format
suitable for <ulink
url="https://developer.mozilla.org/en-US/docs/Server-sent_events/Using_server-sent_events">Server-Sent
Events</ulink>. <literal>cat</literal>
generates a very terse output only
showing the actual message of each
journal entry with no meta data, not
even a timestamp.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--quiet</option></term>
<term><option>-q</option></term>
<listitem><para>Suppresses any warning
message regarding inaccessible system
journals when run as normal
user.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--merge</option></term>
<term><option>-m</option></term>
<listitem><para>Show entries
interleaved from all available
journals, including remote
ones.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--this-boot</option></term>
<term><option>-b</option></term>
<listitem><para>Show data only from
current boot. This will add a match
for <literal>_BOOT_ID=</literal> for
the current boot ID of the
kernel.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--unit=</option></term>
<term><option>-u</option></term>
<listitem><para>Show data only of the
specified unit. This will add a match
for <literal>_SYSTEMD_UNIT=</literal>
for the specified
unit.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>-p</option></term>
<term><option>--priority=</option></term>
<listitem><para>Filter output by
message priorities or priority
ranges. Takes either a single numeric
or textual log level (i.e. between
0/<literal>emerg</literal> and
7/<literal>debug</literal>), or a
range of numeric/text log levels in
the form FROM..TO. The log levels are
the usual syslog log levels as
documented in
<citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
i.e. <literal>emerg</literal> (0),
<literal>alert</literal> (1),
<literal>crit</literal> (2),
<literal>err</literal> (3),
<literal>warning</literal> (4),
<literal>notice</literal> (5),
<literal>info</literal> (6),
<literal>debug</literal> (7). If a
single log level is specified all
messages with this log level or a
lower (hence more important) log level
are shown. If a range is specified all
messages within the range are shown,
including both the start and the end
value of the range. This will add
<literal>PRIORITY=</literal> matches
for the specified
priorities.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--cursor=</option></term>
<term><option>-c</option></term>
<listitem><para>Start showing entries
from the location in the journal
specified by the passed
cursor.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--since=</option></term>
<term><option>--until=</option></term>
<listitem><para>Start showing entries
on or newer than the specified date,
or on or older than the specified
date, respectively. Date specifications should be of
the format "2012-10-30 18:17:16". If
the time part is omitted, 00:00:00 is
assumed. If only the seconds component
is omitted, :00 is assumed. If the
date component is ommitted, the
current day is assumed. Alternatively
the strings
<literal>yesterday</literal>,
<literal>today</literal>,
<literal>tomorrow</literal> are
understood, which refer to 00:00:00 of
the day before the current day, the
current day, or the day after the
current day, respectively. <literal>now</literal>
refers to the current time. Finally,
relative times may be specified,
prefixed with <literal>-</literal> or
<literal>+</literal>, referring to
times before or after the current
time, respectively.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--field=</option></term>
<term><option>-F</option></term>
<listitem><para>Print all possible
data values the specified field can
take in all entries of the
journal.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--directory=</option></term>
<term><option>-D</option></term>
<listitem><para>Takes an absolute
directory path as argument. If
specified journalctl will operate on the
specified journal directory instead of
the default runtime and system journal
paths.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--new-id128</option></term>
<listitem><para>Instead of showing
journal contents generate a new 128
bit ID suitable for identifying
messages. This is intended for usage
by developers who need a new
identifier for a new message they
introduce and want to make
recognizable. Will print the new ID in
three different formats which can be
copied into source code or
similar.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--header</option></term>
<listitem><para>Instead of showing
journal contents show internal header
information of the journal fields
accessed.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--disk-usage</option></term>
<listitem><para>Shows the current disk
usage of all
journal files.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--setup-keys</option></term>
<listitem><para>Instead of showing
journal contents generate a new key
pair for Forward Secure Sealing
(FSS). This will generate a sealing
key and a verification key. The
sealing key is stored in the journal
data directory and shall remain on the
host. The verification key should be
stored externally.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--interval=</option></term>
<listitem><para>Specifies the change
interval for the sealing key, when
generating an FSS key pair with
<option>--setup-keys</option>. Shorter
intervals increase CPU consumption but
shorten the time range of
undetectable journal
alterations. Defaults to
15min.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--verify</option></term>
<listitem><para>Check the journal file
for internal consistency. If the
file has been generated with FSS
enabled, and the FSS verification key
has been specified with
<option>--verify-key=</option>
authenticity of the journal file is
verified.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--verify-key=</option></term>
<listitem><para>Specifies the FSS
verification key to use for the
<option>--verify</option>
operation.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Exit status</title>
<para>On success 0 is returned, a non-zero failure
code otherwise.</para>
</refsect1>
<refsect1>
<title>Environment</title>
<variablelist>
<varlistentry>
<term><varname>$SYSTEMD_PAGER</varname></term>
<listitem><para>Pager to use when
<option>--no-pager</option> is not given;
overrides <varname>$PAGER</varname>. Setting
this to an empty string or the value
<literal>cat</literal> is equivalent to passing
<option>--no-pager</option>.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Examples</title>
<para>Without arguments all collected logs are shown
unfiltered:</para>
<programlisting>journalctl</programlisting>
<para>With one match specified all entries with a field matching the expression are shown:</para>
<programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service</programlisting>
<para>If two different fields are matched only entries matching both expressions at the same time are shown:</para>
<programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097</programlisting>
<para>If two matches refer to the same field all entries matching either expression are shown:</para>
<programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _SYSTEMD_UNIT=dbus.service</programlisting>
<para>If the separator "<literal>+</literal>" is used
two expressions may be combined in a logical OR. The
following will show all messages from the Avahi
service process with the PID 28097 plus all messages
from the D-Bus service (from any of its
processes):</para>
<programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097 + _SYSTEMD_UNIT=dbus.service</programlisting>
<para>Show all logs generated by the D-Bus executable:</para>
<programlisting>journalctl /usr/bin/dbus-daemon</programlisting>
<para>Show all logs of the kernel device node <filename>/dev/sda</filename>:</para>
<programlisting>journalctl /dev/sda</programlisting>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>