systemd/man/sd_path_lookup.xml

<?xml version='1.0'?>
<!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="sd_path_lookup" xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>sd_path_lookup</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>sd_path_lookup</refentrytitle>
    <manvolnum>3</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>sd_path_lookup</refname>
    <refname>sd_path_lookup_strv</refname>

    <refpurpose>Query well-known file system paths</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcsynopsisinfo>#include &lt;systemd/sd-path.h&gt;</funcsynopsisinfo>

      <!-- note: individual constants are not added as <refname>s, there's just too many -->

      <funcsynopsisinfo><token>enum</token> {
        <constant>SD_PATH_TEMPORARY</constant>,
        <constant>SD_PATH_TEMPORARY_LARGE</constant>,

        <constant>SD_PATH_SYSTEM_BINARIES</constant>,
        <constant>SD_PATH_SYSTEM_INCLUDE</constant>,
        <constant>SD_PATH_SYSTEM_LIBRARY_PRIVATE</constant>,
        <constant>SD_PATH_SYSTEM_LIBRARY_ARCH</constant>,
        <constant>SD_PATH_SYSTEM_SHARED</constant>,
        <constant>SD_PATH_SYSTEM_CONFIGURATION_FACTORY</constant>,
        <constant>SD_PATH_SYSTEM_STATE_FACTORY</constant>,

        <constant>SD_PATH_SYSTEM_CONFIGURATION</constant>,
        <constant>SD_PATH_SYSTEM_RUNTIME</constant>,
        <constant>SD_PATH_SYSTEM_RUNTIME_LOGS</constant>,
        <constant>SD_PATH_SYSTEM_STATE_PRIVATE</constant>,
        <constant>SD_PATH_SYSTEM_STATE_LOGS</constant>,
        <constant>SD_PATH_SYSTEM_STATE_CACHE</constant>,
        <constant>SD_PATH_SYSTEM_STATE_SPOOL</constant>,

        <constant>SD_PATH_USER_BINARIES</constant>,
        <constant>SD_PATH_USER_LIBRARY_PRIVATE</constant>,
        <constant>SD_PATH_USER_LIBRARY_ARCH</constant>,
        <constant>SD_PATH_USER_SHARED</constant>,

        <constant>SD_PATH_USER_CONFIGURATION</constant>,
        <constant>SD_PATH_USER_RUNTIME</constant>,
        <constant>SD_PATH_USER_STATE_CACHE</constant>,

        <constant>SD_PATH_USER</constant>,
        <constant>SD_PATH_USER_DOCUMENTS</constant>,
        <constant>SD_PATH_USER_MUSIC</constant>,
        <constant>SD_PATH_USER_PICTURES</constant>,
        <constant>SD_PATH_USER_VIDEOS</constant>,
        <constant>SD_PATH_USER_DOWNLOAD</constant>,
        <constant>SD_PATH_USER_PUBLIC</constant>,
        <constant>SD_PATH_USER_TEMPLATES</constant>,
        <constant>SD_PATH_USER_DESKTOP</constant>,

        <constant>SD_PATH_SEARCH_BINARIES</constant>,
        <constant>SD_PATH_SEARCH_BINARIES_DEFAULT</constant>,
        <constant>SD_PATH_SEARCH_LIBRARY_PRIVATE</constant>,
        <constant>SD_PATH_SEARCH_LIBRARY_ARCH</constant>,
        <constant>SD_PATH_SEARCH_SHARED</constant>,
        <constant>SD_PATH_SEARCH_CONFIGURATION_FACTORY</constant>,
        <constant>SD_PATH_SEARCH_STATE_FACTORY</constant>,
        <constant>SD_PATH_SEARCH_CONFIGURATION</constant>,

        <constant>SD_PATH_SYSTEMD_UTIL</constant>,
        <constant>SD_PATH_SYSTEMD_SYSTEM_UNIT</constant>,
        <constant>SD_PATH_SYSTEMD_SYSTEM_PRESET</constant>,
        <constant>SD_PATH_SYSTEMD_USER_UNIT</constant>,
        <constant>SD_PATH_SYSTEMD_USER_PRESET</constant>,
        <constant>SD_PATH_SYSTEMD_SYSTEM_CONF</constant>,
        <constant>SD_PATH_SYSTEMD_USER_CONF</constant>,
        <constant>SD_PATH_SYSTEMD_SEARCH_SYSTEM_UNIT</constant>,
        <constant>SD_PATH_SYSTEMD_SEARCH_USER_UNIT</constant>,
        <constant>SD_PATH_SYSTEMD_SYSTEM_GENERATOR</constant>,
        <constant>SD_PATH_SYSTEMD_USER_GENERATOR</constant>,
        <constant>SD_PATH_SYSTEMD_SEARCH_SYSTEM_GENERATOR</constant>,
        <constant>SD_PATH_SYSTEMD_SEARCH_USER_GENERATOR</constant>,
        <constant>SD_PATH_SYSTEMD_SLEEP</constant>,
        <constant>SD_PATH_SYSTEMD_SHUTDOWN</constant>,

        <constant>SD_PATH_TMPFILES</constant>,
        <constant>SD_PATH_SYSUSERS</constant>,
        <constant>SD_PATH_SYSCTL</constant>,
        <constant>SD_PATH_BINFMT</constant>,
        <constant>SD_PATH_MODULES_LOAD</constant>,
        <constant>SD_PATH_CATALOG</constant>,

        <constant>SD_PATH_SYSTEMD_SEARCH_NETWORK</constant>,
};</funcsynopsisinfo>

      <funcprototype>
        <funcdef>int <function>sd_path_lookup</function></funcdef>
        <paramdef>uint64_t <parameter>type</parameter></paramdef>
        <paramdef>const char *<parameter>suffix</parameter></paramdef>
        <paramdef>char **<parameter>paths</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_path_lookup_strv</function></funcdef>
        <paramdef>uint64_t <parameter>type</parameter></paramdef>
        <paramdef>const char *<parameter>suffix</parameter></paramdef>
        <paramdef>char ***<parameter>paths</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><function>sd_path_lookup()</function> and <function>sd_bus_path_lookup_strv()</function> return a
    single path or set of file system paths specified by the argument <parameter>type</parameter>. In case of
    <function>sd_path_lookup()</function> a single <constant>NUL</constant>-terminated string is returned.
    When <parameter>type</parameter> specifies a set of paths, they are concatenated using
    <literal>:</literal> as a separator (as is traditionally done for e.g. <varname>$PATH</varname> or
    <varname>$LD_LIBRARY_PATH</varname>). In case of <function>sd_path_lookup_strv()</function> a
    <constant>NULL</constant>-terminated array of strings is returned (strv). If suffix
    <parameter>suffix</parameter> is given, it is concatenated to each of the paths after a slash
    (<literal>/</literal>). All returned paths are absolute.</para>

    <para>For paths which refer to user directories, the relevant XDG standard is followed, with support for
    environment variables like <varname>$XDG_DOCUMENTS_DIR</varname>, <varname>$XDG_DESKTOP_DIR</varname>,
    ..., and explicit configuration in <filename>/etc/xdg/user-dirs.conf</filename> or
    <filename>${XDG_CONFIG_HOME}/user-dirs.dirs</filename>. See
    <ulink url="https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html">
      XDG Base Directory Specification</ulink> for details.</para>

    <para><citerefentry><refentrytitle>systemd-path</refentrytitle><manvolnum>1</manvolnum></citerefentry> is
    a wrapper around <function>sd_path_lookup()</function> and allows the same set of paths to be queried.
    </para>
  </refsect1>

  <refsect1>
    <title>Return Value</title>

    <para>On success, <function>sd_path_lookup()</function> and <function>sd_path_lookup_strv()</function>
    return a non-negative integer. On failure, a negative errno-style error number is returned by either
    function.</para>

    <para>The returned string or string array (strv) must be
    <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>'d by the
    caller.</para>

    <refsect2 id='errors'>
      <title>Errors</title>

      <para>Returned errors may indicate the following problems:</para>

      <variablelist>
        <varlistentry>
          <term><constant>-EOPNOTSUPP</constant></term>

          <listitem><para>Unknown identifier <parameter>type</parameter>.</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><constant>-EINVAL</constant></term>

          <listitem><para>Output argument is <constant>NULL</constant>.</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><constant>-ENXIO</constant></term>

          <listitem><para>Query failed because of an undefined environment variable (e.g. for
          <constant>SD_PATH_USER_RUNTIME</constant> when <varname>$XDG_RUNTIME_DIR</varname> is not
          defined).</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><constant>-ENOMEM</constant></term>

          <listitem><para>Memory allocation failed.</para></listitem>
        </varlistentry>
      </variablelist>
    </refsect2>
  </refsect1>

  <refsect1>
    <title>Examples</title>

    <refsect2>
      <title>Look up the location of ~/Documents</title>

      <programlisting><xi:include href="path-documents.c" parse="text" /></programlisting>
      <para>Note that the default answer of <filename index='false'>$HOME/Documents</filename> may be
      overridden by <filename index='false'>user-dirs.conf</filename> or
      <varname>$XDG_DOCUMENTS_DIR</varname>.</para>
    </refsect2>
  </refsect1>

  <xi:include href="libsystemd-pkgconfig.xml" />

  <refsect1>
    <title>See Also</title>

    <para>
      <citerefentry><refentrytitle>systemd-path</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>