Rework unit_name_mangle_with_suffix() to (very slightly) simplify the path

[thirdparty/systemd.git] / man / systemd-escape.xml

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->

<refentry id="systemd-escape"
    xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>systemd-escape</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>systemd-escape</refentrytitle>
    <manvolnum>1</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>systemd-escape</refname>
    <refpurpose>Escape strings for usage in systemd unit names</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>systemd-escape</command>
      <arg choice="opt" rep="repeat">OPTIONS</arg>
      <arg choice="opt" rep="repeat">STRING</arg>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><command>systemd-escape</command> may be used to escape
    strings for inclusion in systemd unit names. The command may be
    used to escape and to undo escaping of strings.</para>

    <para>The command takes any number of strings on the command line,
    and will process them individually, one after another. It will
    output them separated by spaces to stdout.</para>

    <para>By default, this command will escape the strings passed,
    unless <option>--unescape</option> is passed which results in the
    inverse operation being applied. If <option>--mangle</option> is given, a
    special mode of escaping is applied instead, which assumes the
    string is already escaped but will escape everything that
    appears obviously non-escaped.</para>

    <para>For details on the escaping and unescaping algorithms see the relevant section in
    <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
  </refsect1>

  <refsect1>
    <title>Options</title>

    <para>The following options are understood:</para>

    <variablelist>
      <varlistentry>
        <term><option>--suffix=</option></term>

        <listitem><para>Appends the specified unit type suffix to the
        escaped string. Takes one of the unit types supported by
        systemd, such as <literal>service</literal> or
        <literal>mount</literal>. May not be used in conjunction with
        <option>--template=</option>, <option>--unescape</option> or
        <option>--mangle</option>.</para>

        <xi:include href="version-info.xml" xpointer="v216"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--template=</option></term>

        <listitem><para>Inserts the escaped strings in a unit name
        template. Takes a unit name template such as
        <filename>foobar@.service</filename>. With
        <option>--unescape</option>, expects instantiated unit names
        for this template and extracts and unescapes just the instance
        part. May not be used in conjunction with
        <option>--suffix=</option>,
        <option>--instance</option> or
        <option>--mangle</option>.</para>

        <xi:include href="version-info.xml" xpointer="v216"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--path</option></term>
        <term><option>-p</option></term>

        <listitem><para>When escaping or unescaping a string, assume it refers to a file system path. This
        simplifies the path (leading, trailing, and duplicate <literal>/</literal> characters are removed,
        no-op path <literal>.</literal> components are removed, and for absolute paths, leading
        <literal>..</literal> components are removed). After the simplification, the path must not contain
        <literal>..</literal>.</para>

        <para>This is particularly useful for generating strings suitable for unescaping with the
        <literal>%f</literal> specifier in unit files, see
        <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
        </para>

        <xi:include href="version-info.xml" xpointer="v216"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--unescape</option></term>
        <term><option>-u</option></term>

        <listitem><para>Instead of escaping the specified strings,
        undo the escaping, reversing the operation. May not be used in
        conjunction with <option>--suffix=</option> or
        <option>--mangle</option>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--mangle</option></term>
        <term><option>-m</option></term>

        <listitem><para>Like <option>--escape</option>, but only
        escape characters that are obviously not escaped yet, and
        possibly automatically append an appropriate unit type suffix
        to the string. May not be used in conjunction with
        <option>--suffix=</option>, <option>--template=</option> or
        <option>--unescape</option>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--instance</option></term>

        <listitem><para>With <option>--unescape</option>, unescape
        and print only the instance part of an instantiated unit name
        template. Results in an error for an uninstantiated template
        like <filename>ssh@.service</filename> or a non-template name
        like <filename>ssh.service</filename>.
        Must be used in conjunction with <option>--unescape</option>
        and may not be used in conjunction with
        <option>--template</option>.</para>

        <xi:include href="version-info.xml" xpointer="v240"/></listitem>
      </varlistentry>

      <xi:include href="standard-options.xml" xpointer="help" />
      <xi:include href="standard-options.xml" xpointer="version" />
    </variablelist>

  </refsect1>

  <refsect1>
    <title>Examples</title>

    <para>To escape a single string:</para>
    <programlisting>$ systemd-escape 'Hallöchen, Meister'
Hall\xc3\xb6chen\x2c\x20Meister</programlisting>

    <para>To undo escaping on a single string:</para>
    <programlisting>$ systemd-escape -u 'Hall\xc3\xb6chen\x2c\x20Meister'
Hallöchen, Meister</programlisting>

    <para>To generate the mount unit for a path:</para>
    <programlisting>$ systemd-escape -p --suffix=mount "/tmp//waldi/foobar/"
tmp-waldi-foobar.mount</programlisting>

    <para>To generate instance names of three strings:</para>
    <programlisting>$ systemd-escape --template=systemd-nspawn@.service 'My Container 1' 'containerb' 'container/III'
systemd-nspawn@My\x20Container\x201.service systemd-nspawn@containerb.service systemd-nspawn@container-III.service</programlisting>

    <para>To extract the instance part of an instantiated unit:</para>
    <programlisting>$ systemd-escape -u --instance 'systemd-nspawn@My\x20Container\x201.service'
My Container 1</programlisting>

    <para>To extract the instance part of an instance of a particular template:</para>
    <programlisting>$ systemd-escape -u --template=systemd-nspawn@.service 'systemd-nspawn@My\x20Container\x201.service'
My Container 1</programlisting>
  </refsect1>

  <refsect1>
    <title>Exit status</title>

    <para>On success, 0 is returned, a non-zero failure code
    otherwise.</para>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>