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systemd-stable/man/journalctl.xml
Zbigniew Jędrzejewski-Szmek f11880744c journalctl: add --list-boots to show boot IDs and times
Suggested by David Wilkins <dwilkins@maths.tcd.ie> in
https://bugzilla.redhat.com/show_bug.cgi?id=967521:

> [Specific boot ID is a] bit of a palaver to obtain.  I consulted the
> verbose dump of the journal to discover the _BOOT_ID for the
> timestamp, and then generated the journal dump for that boot using
> journalctl _BOOT_ID=foo -o short-monotonic.
2013-10-28 23:43:57 -04:00

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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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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</command>
<arg choice="opt" rep="repeat">OPTIONS</arg>
<arg choice="opt" rep="repeat">MATCHES</arg>
</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 parameters, 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. Similarly, 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 of 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>systemd-journal</literal>
group get access to the system journal and the
journals of other users.</para>
<para>The output is paged through
<command>less</command> by default, and long lines are
"truncated" to screen width. The hidden part can be
viewed by using the left-arrow and right-arrow
keys. Paging can be disabled, see
<option>--no-pager</option> and section Environment
below.</para>
<para>When outputing to a tty, lines are colored
according to priority: lines of level ERROR and higher
are colored red, lines of level NOTICE and higher are
highlighted, and other lines are displayed normally.
</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>The following options are understood:</para>
<variablelist>
<varlistentry>
<term><option>-h</option></term>
<term><option>--help</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>--no-full</option></term>
<term><option>--full</option></term>
<term><option>-l</option></term>
<listitem><para>Ellipsize fields when
they do not fit in available columns.
The default is to show full fields,
allowing them to wrap or be truncated
by the pager if one is used.</para>
<para>The old options
<option>-l</option>/<option>--full</option>
are not useful anymore, except to undo
<option>--no-full</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>-a</option></term>
<term><option>--all</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>-f</option></term>
<term><option>--follow</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>-e</option></term>
<term><option>--pager-end</option></term>
<listitem><para>Immediately jump to
the end of the journal inside the
implied pager tool. This implies
<option>-n1000</option> to guarantee
that the pager will not buffer logs of
unbounded size. This may be overridden
with an explicit <option>-n</option>
with some other numeric value on the
command line. Note that this option is
only supported for the
<citerefentry><refentrytitle>less</refentrytitle><manvolnum>1</manvolnum></citerefentry>
pager.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>-n</option></term>
<term><option>--lines=</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>-r</option></term>
<term><option>--reverse</option></term>
<listitem><para>Reverse output, so the newest
entries are displayed first.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>-o</option></term>
<term><option>--output=</option></term>
<listitem><para>Controls the
formatting of the journal entries that
are shown. Takes one of the following options:
</para>
<variablelist>
<varlistentry>
<term>
<option>short</option>
</term>
<listitem>
<para>is the default
and generates an output
that is mostly identical
to the formatting of
classic syslog files,
showing one line per
journal entry.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<option>short-iso</option>
</term>
<listitem>
<para>is very similar,
but shows ISO 8601
wallclock timestamps.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<option>short-precise</option>
</term>
<listitem>
<para>is very similar,
but shows timestamps
with full microsecond
precision.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<option>short-monotonic</option>
</term>
<listitem>
<para>is very similar,
but shows monotonic
timestamps instead of
wallclock timestamps.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<option>verbose</option>
</term>
<listitem>
<para>shows the
full-structured entry
items with all fields.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<option>export</option>
</term>
<listitem>
<para>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).</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<option>json</option>
</term>
<listitem>
<para>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).</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<option>json-pretty</option>
</term>
<listitem>
<para>formats entries as
JSON data structures,
but formats them in
multiple lines in order
to make them more
readable for humans.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<option>json-sse</option>
</term>
<listitem>
<para>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>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<option>cat</option>
</term>
<listitem>
<para>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>
</variablelist>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-x</option></term>
<term><option>--catalog</option></term>
<listitem><para>Augment log lines with
explanation texts from the message
catalog. This will add explanatory
help texts to log messages in the
output where this is available. These
short help texts will explain the
context of an error or log event,
possible solutions, as well as
pointers to support forums, developer
documentation, and any other relevant
manuals. Note that help texts are not
available for all messages, but only
for selected ones. For more
information on the message catalog,
please refer to the <ulink
url="http://www.freedesktop.org/wiki/Software/systemd/catalog">Message
Catalog Developer
Documentation</ulink>.</para>
<para>Note: when attaching
<command>journalctl</command> output
to bug reports, please do
<emphasis>not</emphasis> use
<option>-x</option>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-q</option></term>
<term><option>--quiet</option></term>
<listitem><para>Suppresses any warning
message regarding inaccessible system
journals when run as normal
user.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>-m</option></term>
<term><option>--merge</option></term>
<listitem><para>Show entries
interleaved from all available
journals, including remote
ones.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>-b <optional><replaceable>ID</replaceable></optional><optional><replaceable>±offset</replaceable></optional></option></term>
<term><option>--boot=<optional><replaceable>ID</replaceable></optional><optional><replaceable>±offset</replaceable></optional></option></term>
<listitem><para>Show messages from a specific
boot. This will add a match for
<literal>_BOOT_ID=</literal>.</para>
<para>The argument may be empty, in which case
logs for the current boot will be shown.</para>
<para>If the boot ID is omitted, a positive
<replaceable>offset</replaceable> will look up
the boots starting from the beginning of the
journal, and a equal-or-less-than zero
<replaceable>offset</replaceable> will look up
boots starting from the end of the
journal. Thus, <constant>1</constant> means the
first boot found in the journal in the
chronological order, <constant>2</constant> the
second and so on; while <constant>-0</constant>
is the last boot, <constant>-1</constant> the
boot before that, and so on. An empty
<replaceable>offset</replaceable> is equivalent
to specifying <constant>-0</constant>, except
when the current boot is not the last boot
(e.g. because <option>--directory</option> was
specified to look at logs from a different
machine).</para>
<para>If the 32 character
<replaceable>ID</replaceable> is specified, it
may optionally be followed by
<replaceable>offset</replaceable> which
identifies the boot relative to the one given by
boot <replaceable>ID</replaceable>. Negative
values mean earlier boots and a positive values
mean later boots. If
<replaceable>offset</replaceable> is not
specified, a value of zero is assumed and the
logs for the boot given by
<replaceable>ID</replaceable> are shown.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--list-boots</option></term>
<listitem><para>Show a tabular list of
boot numbers (relative to current
boot), their IDs, and the timestamps
of the first and last message
pertaining to the boot.
</para></listitem>
</varlistentry>
<varlistentry>
<term><option>-k</option></term>
<term><option>--dmesg</option></term>
<listitem><para>Show only kernel messages. This
implies <option>-b</option> and adds the match
<literal>_TRANSPORT=kernel</literal>.
</para></listitem>
</varlistentry>
<varlistentry>
<term><option>-u</option></term>
<term><option>--unit=</option></term>
<listitem><para>Show messages for the
specified systemd unit. This will add
a match for messages from the unit
(<literal>_SYSTEMD_UNIT=</literal>)
and additional matches for messages
from systemd and messages about
coredumps for the specified unit.</para>
<para>This parameter can be specified multiple times.
</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--user-unit=</option></term>
<listitem><para>Show messages for the
specified user session unit. This will
add a match for messages from the unit
(<literal>_SYSTEMD_USER_UNIT=</literal>
and <literal>_UID=</literal>) and
additional matches for messages from
session systemd and messages about
coredumps for the specified unit.</para>
<para>This parameter can be specified multiple times.
</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>-c</option></term>
<term><option>--cursor=</option></term>
<listitem><para>Start showing entries
from the location in the journal
specified by the passed
cursor.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--after-cursor=</option></term>
<listitem><para>Start showing entries from the
location in the journal
<emphasis>after</emphasis> the location
specified by the this 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
<literal>2012-10-30 18:17:16</literal>.
If the time part is omitted,
<literal>00:00:00</literal> is assumed.
If only the seconds component is omitted,
<literal>:00</literal> is assumed. If the
date component is omitted, 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>-F</option></term>
<term><option>--field=</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>--system</option></term>
<term><option>--user</option></term>
<listitem><para>Show messages from
system services and the kernel (with
<option>--system</option>). Show
messages from service of current user
(with <option>--user</option>).
If neither is specified, show all
messages that the user can see.
</para></listitem>
</varlistentry>
<varlistentry>
<term><option>-D <replaceable>DIR</replaceable></option></term>
<term><option>--directory=<replaceable>DIR</replaceable></option></term>
<listitem><para>Takes a directory path
as argument. If specified, journalctl
will operate on the specified journal
directory
<replaceable>DIR</replaceable> instead
of the default runtime and system
journal paths.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--file=<replaceable>GLOB</replaceable></option></term>
<listitem><para>Takes a file glob as
argument. If specified, journalctl will
operate on the specified journal files
matching <replaceable>GLOB</replaceable>
instead of the default runtime and
system journal paths. May be specified
multiple times, in which case files will
be suitably interleaved.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--root=<replaceable>ROOT</replaceable></option></term>
<listitem><para>Takes a directory path
as argument. If specified, journalctl
will operate on catalog file hierarchy
underneath the specified directory
instead of the root directory
(e.g. <option>--update-catalog</option>
will create
<filename><replaceable>ROOT</replaceable>/var/lib/systemd/catalog/database</filename>).
</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. This 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>--list-catalog
<optional><replaceable>ID128...</replaceable></optional>
</option></term>
<listitem><para>List the contents of
the message catalog, as table of
message IDs plus their short
description strings.</para>
<para>If any
<replaceable>ID128</replaceable>s are
specified, only those entries are shown.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--dump-catalog
<optional><replaceable>ID128...</replaceable></optional>
</option></term>
<listitem><para>Show the contents of
the message catalog, with entries
separated by a line consisting of two
dashes and the id (the format is the
same as <filename>.catalog</filename>
files.</para>
<para>If any
<replaceable>ID128</replaceable>s are
specified, only those entries are shown.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--update-catalog</option></term>
<listitem><para>Update the message
catalog index. This command needs to
be executed each time new catalog
files are installed, removed or
updated to rebuild the binary catalog
index.</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. Also see the
<option>Seal=</option> option in
<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--force</option></term>
<listitem><para>When --setup-keys is passed and
Forward Secure Sealing has already been set up,
recreate FSS keys.</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 class='environment-variables'>
<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 noindex='true'>/dev/sda</filename>:</para>
<programlisting>journalctl /dev/sda</programlisting>
<para>Show all kernel logs from previous boot:</para>
<programlisting>journalctl -k -b -1</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>