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It is not true that "no string" is written to journal; the binary name is used when run via `systemd-cat command`, or `cat` is used when run via `command | systemd-cat`.
187 lines
6.9 KiB
XML
187 lines
6.9 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
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<refentry id="systemd-cat"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>systemd-cat</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd-cat</refentrytitle>
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<manvolnum>1</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd-cat</refname>
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<refpurpose>Connect a pipeline or program's output with the journal</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<cmdsynopsis>
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<command>systemd-cat</command> <arg choice="opt" rep="repeat">OPTIONS</arg> <arg>COMMAND</arg> <arg choice="opt" rep="repeat">ARGUMENTS</arg>
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</cmdsynopsis>
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<cmdsynopsis>
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<command>systemd-cat</command> <arg choice="opt" rep="repeat">OPTIONS</arg>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><command>systemd-cat</command> may be used to connect the
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standard input and output of a process to the journal, or as a
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filter tool in a shell pipeline to pass the output the previous
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pipeline element generates to the journal.</para>
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<para>If no parameter is passed, <command>systemd-cat</command>
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will write everything it reads from standard input (stdin) to the
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journal.</para>
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<para>If parameters are passed, they are executed as command line
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with standard output (stdout) and standard error output (stderr)
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connected to the journal, so that all it writes is stored in the
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journal.</para>
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</refsect1>
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<refsect1>
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<title>Options</title>
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<para>The following options are understood:</para>
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<variablelist>
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<xi:include href="standard-options.xml" xpointer="help" />
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<xi:include href="standard-options.xml" xpointer="version" />
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<varlistentry>
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<term><option>-t</option></term>
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<term><option>--identifier=</option></term>
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<listitem><para>Specify a short string that is used to
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identify the logging tool. If not specified, no identification
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string is set for the journal entry, and the executable name
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(or <literal>cat</literal> if the input is read from a pipe)
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will be used to describe the log source instead.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-p</option></term>
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<term><option>--priority=</option></term>
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<listitem><para>Specify the default priority level for the
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logged messages. Pass one of
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<literal>emerg</literal>,
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<literal>alert</literal>,
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<literal>crit</literal>,
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<literal>err</literal>,
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<literal>warning</literal>,
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<literal>notice</literal>,
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<literal>info</literal>,
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<literal>debug</literal>, or a
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value between 0 and 7 (corresponding to the same named
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levels). These priority values are the same as defined by
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<citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
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Defaults to <literal>info</literal>. Note that this simply
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controls the default, individual lines may be logged with
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different levels if they are prefixed accordingly. For details,
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see <option>--level-prefix=</option> below.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--stderr-priority=</option></term>
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<listitem><para>Specifies the default priority level for
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messages from the process's standard error output (stderr).
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Usage of this option is the same as the
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<option>--priority=</option> option, above, and both can be
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used at once. When both are used, <option>--priority=</option>
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will specify the default priority for standard output (stdout).
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</para>
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<para>If <option>--stderr-priority=</option> is not specified,
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messages from stderr will still be logged, with the same
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default priority level as stdout.</para>
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<para>Also, note that when stdout and stderr use the same
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default priority, the messages will be strictly ordered,
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because one channel is used for both. When the default priority
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differs, two channels are used, and so stdout messages will not
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be strictly ordered with respect to stderr messages - though
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they will tend to be approximately ordered.</para>
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<xi:include href="version-info.xml" xpointer="v241"/></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--level-prefix=</option></term>
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<listitem><para>Controls whether lines read are parsed for syslog priority level prefixes. If enabled
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(the default), a line prefixed with a priority prefix such as <literal><5></literal> is logged
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at priority 5 (<literal>notice</literal>), and similarly for the other priority levels. Takes a
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boolean argument.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--namespace=</option></term>
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<listitem><para>Specifies the journal namespace to which the standard IO should be connected.
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For details about journal namespaces, see
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<citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
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</para>
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<xi:include href="version-info.xml" xpointer="v256"/></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Exit status</title>
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<para>On success, 0 is returned, a non-zero failure code otherwise.</para>
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</refsect1>
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<refsect1>
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<title>Examples</title>
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<example>
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<title>Invoke a program</title>
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<para>This calls <filename index="false">/bin/ls</filename>
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with standard output and error connected to the journal:</para>
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<programlisting># systemd-cat ls</programlisting>
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</example>
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<example>
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<title>Usage in a shell pipeline</title>
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<para>This builds a shell pipeline also invoking
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<filename>/bin/ls</filename> and writes the output it generates
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to the journal:</para>
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<programlisting># ls | systemd-cat</programlisting>
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</example>
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<para>Even though the two examples have very similar effects, the first is preferable, since only one
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process is running at a time and both stdout and stderr are captured, while in the second example, only
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stdout is captured.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para><simplelist type="inline">
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<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
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<member><citerefentry project='man-pages'><refentrytitle>logger</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
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</simplelist></para>
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</refsect1>
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</refentry>
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