specifically the hierarchy described in the <ulink
url="http://refspecs.linuxfoundation.org/FHS_2.3/fhs-2.3.html">File
System Hierarchy</ulink> specification and
- <citerefentry><refentrytitle>hier</refentrytitle><manvolnum>7</manvolnum></citerefentry>. This
+ <citerefentry project='man-pages'><refentrytitle>hier</refentrytitle><manvolnum>7</manvolnum></citerefentry>. This
manual page describes a more minimal, modernized
subset of these specifications that defines more
strictly the suggestions and restrictions systemd
makes on the file system hierarchy.</para>
+
+ <para>Many of the paths described here are queriable
+ with the
+ <citerefentry><refentrytitle>systemd-path</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ tool.</para>
</refsect1>
<refsect1>
root. Usually writable, but this is
not required. Possibly a temporary
file system (<literal>tmpfs</literal>). Not shared with
- other hosts (unless read-only). The
- administrator may create additional
- top-level subdirectories in this tree,
- if required and the name does not
- conflict with any of the directories
- listed below.</para></listitem>
+ other hosts (unless read-only).
+ </para></listitem>
</varlistentry>
<varlistentry>
used for bringing up the system. On
EFI systems this is possibly the EFI
System Partition, also see
- <citerefentry><refentrytitle>systemd-boot-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>. This
+ <citerefentry><refentrytitle>systemd-efi-boot-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>. This
directory is usually strictly local
- the host, and should be considered
+ to the host, and should be considered
read-only, except when a new kernel or
boot loader is installed. This
directory only exists on systems that
system users. This directory and
possibly the directories contained
within it might only become available
- or writable in late boot or even on
- user login only. This directory might
- be placed on limited-functionality
+ or writable in late boot or even only
+ after user authentication. This directory
+ might be placed on limited-functionality
network file systems, hence
applications should not assume the
full set of file API is available on
<listitem><para>The place for small
temporary files. This directory is
usually mounted as
- <literal>tmpfs</literal> instance, and
+ a <literal>tmpfs</literal> instance, and
should hence not be used for larger
files. (Use
<filename>/var/tmp</filename> for
accessible to other users of the
system it is essential that this
directory is only written to with the
- <citerefentry><refentrytitle>mkstemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>mkdtemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ <citerefentry project='man-pages'><refentrytitle>mkstemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry project='man-pages'><refentrytitle>mkdtemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>
and related calls. This directory is
usually flushed at boot-up. Also,
files that are not accessed within a
certain time are usually automatically
deleted. If applications find the
environment variable
- <varname>$TMP</varname> set they
+ <varname>$TMPDIR</varname> set they
should prefer using the directory
specified in it over directly
referencing
- <filename>/tmp</filename>.</para></listitem>
+ <filename>/tmp</filename> (see <citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ and
+ <ulink url="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03">IEEE Std 1003.1</ulink> for details).</para></listitem>
</varlistentry>
</variablelist>
<varlistentry>
<term><filename>/usr/bin</filename></term>
- <listitem><para>Binaries for user
- commands, that shall appear in the
+ <listitem><para>Binaries and
+ executables for user commands, that
+ shall appear in the
<varname>$PATH</varname> search
path. It is recommended not to place
binaries in this directory that are
<varlistentry>
<term><filename>/usr/lib</filename></term>
- <listitem><para>Static vendor data
- that is compatible with all
+ <listitem><para>Static, private vendor
+ data that is compatible with all
architectures (though not necessarily
architecture-independent). Note that
- this includes internal
- executables or other binaries that are
- not regularly invoked from a
- shell. Such binaries may be for any
- architecture supported by the
- system. Do not place public libraries
- in this directory, use
+ this includes internal executables or
+ other binaries that are not regularly
+ invoked from a shell. Such binaries
+ may be for any architecture supported
+ by the system. Do not place public
+ libraries in this directory, use
<varname>$libdir</varname> (see
below), instead.</para></listitem>
</varlistentry>
<varlistentry>
- <term><varname>$libdir</varname></term>
+ <term><filename>/usr/lib/<replaceable>arch-id</replaceable></filename></term>
<listitem><para>Location for placing
- dynamic libraries in. The precise
- location depends on the operating
- system and the architecture, and is
- sometimes
+ dynamic libraries, also called <varname>$libdir</varname>.
+ The architecture identifier to use is defined on <ulink
+ url="https://wiki.debian.org/Multiarch/Tuples">Multiarch Architecture Specifiers (Tuples)</ulink>
+ list. Legacy locations of <varname>$libdir</varname> are
<filename>/usr/lib</filename>,
- <filename>/use/lib64</filename> or
- <filename>/usr/lib/</filename>
- suffixed by an architecture
- identifier. This directory should not
+ <filename>/usr/lib64</filename>.
+ This directory should not
be used for package-specific data,
unless this data is
- architecture-dependent,
- too.</para></listitem>
+ architecture-dependent, too. To query
+ <varname>$libdir</varname> for the
+ primary architecture of the system,
+ invoke:
+ <programlisting># pkg-config --variable=libdir systemd</programlisting> or
+ <programlisting># systemd-path system-library-arch</programlisting>
+ </para></listitem>
+
</varlistentry>
<varlistentry>
private logs in this directory, though
it is recommended to do most logging
via the
- <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
and
<citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry>
calls.</para></listitem>
restrictions as with
<filename>/tmp</filename> apply, and
hence only
- <citerefentry><refentrytitle>mkstemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>mkdtemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ <citerefentry project='man-pages'><refentrytitle>mkstemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry project='man-pages'><refentrytitle>mkdtemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>
or similar calls should be used to
make use of this directory. If
applications find the environment
- variable <varname>$TMP</varname> set
- they should prefer using the directory
- specified in it over directly
- referencing
- <filename>/var/tmp</filename>.
+ variable <varname>$TMPDIR</varname>
+ set they should prefer using the
+ directory specified in it over
+ directly referencing
+ <filename>/var/tmp</filename> (see <citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ for details).
</para></listitem>
</varlistentry>
<term><filename>/dev</filename></term>
<listitem><para>The root directory for
device nodes. Usually this directory
- is mounted as
+ is mounted as a
<literal>devtmpfs</literal> instance,
but might be of a different type in
sandboxed/containerized setups. This
programs) or
<varname>$XDG_RUNTIME_DIR</varname>
(for user programs) instead of POSIX
- shared memory segments, since they
+ shared memory segments, since those
directories are not world-writable and
hence not vulnerable to
security-sensitive name
is mostly an API to interface with the
kernel and not a place where normal
files may be stored. For details, see
- <citerefentry><refentrytitle>proc</refentrytitle><manvolnum>5</manvolnum></citerefentry>. A
+ <citerefentry project='man-pages'><refentrytitle>proc</refentrytitle><manvolnum>5</manvolnum></citerefentry>. A
number of special purpose virtual file
systems might be mounted below this
directory.</para></listitem>
</variablelist>
</refsect1>
+ <refsect1>
+ <title>Home Directory</title>
+
+ <para>User applications may want to place files and
+ directories in the user's home directory. They should
+ follow the following basic structure. Note that some
+ of these directories are also standardized (though
+ more weakly) by the <ulink
+ url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
+ Base Directory Specification</ulink>. Additional
+ locations for high-level user resources are defined by
+ <ulink
+ url="http://www.freedesktop.org/wiki/Software/xdg-user-dirs/">xdg-user-dirs</ulink>.</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><filename>~/.cache</filename></term>
+
+ <listitem><para>Persistent user cache
+ data. User programs may place
+ non-essential data in this
+ directory. Flushing this directory
+ should have no effect on operation of
+ programs, except for increased
+ runtimes necessary to rebuild these
+ caches. If an application finds
+ <varname>$XDG_CACHE_HOME</varname> set
+ is should use the directory specified
+ in it instead of this
+ directory.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><filename>~/.config</filename></term>
+
+ <listitem><para>Application
+ configuration and state. When a new
+ user is created this directory will be
+ empty or not exist at
+ all. Applications should fall back to
+ defaults should their configuration or
+ state in this directory be missing. If
+ an application finds
+ <varname>$XDG_CONFIG_HOME</varname> set
+ is should use the directory specified
+ in it instead of this
+ directory.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><filename>~/.local/bin</filename></term>
+
+ <listitem><para>Executables that shall
+ appear in the user's
+ <varname>$PATH</varname> search
+ path. It is recommended not to place
+ executables in this directory that are
+ not useful for invocation from a
+ shell; these should be placed in a
+ subdirectory of
+ <filename>~/.local/lib</filename>
+ instead. Care should be taken when
+ placing architecture-dependent
+ binaries in this place which might be
+ problematic if the home directory is
+ shared between multiple hosts with
+ different
+ architectures.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><filename>~/.local/lib</filename></term>
+
+ <listitem><para>Static, private vendor
+ data that is compatible with all
+ architectures.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><filename>~/.local/lib/<replaceable>arch-id</replaceable></filename></term>
+
+ <listitem><para>Location for placing
+ public dynamic libraries. The architecture
+ identifier to use, is defined on <ulink
+ url="https://wiki.debian.org/Multiarch/Tuples">Multiarch Architecture Specifiers (Tuples)</ulink>
+ list.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><filename>~/.local/share</filename></term>
+
+ <listitem><para>Resources shared
+ between multiple packages, such as
+ fonts or artwork. Usually, the precise
+ location and format of files stored
+ below this directory is subject to
+ specifications that ensure
+ interoperability. If
+ an application finds
+ <varname>$XDG_DATA_HOME</varname> set
+ is should use the directory specified
+ in it instead of this
+ directory.</para></listitem>
+ </varlistentry>
+
+ </variablelist>
+ </refsect1>
+
+
+ <refsect1>
+ <title>Unprivileged Write Access</title>
+
+ <para>Unprivileged processes generally lack
+ write access to most of the hierarchy.</para>
+
+ <para>The exceptions for normal users are
+ <filename>/tmp</filename>,
+ <filename>/var/tmp</filename>,
+ <filename>/dev/shm</filename>, as well as the home
+ directory <varname>$HOME</varname> (usually found
+ below <filename>/home</filename>) and the runtime
+ directory <varname>$XDG_RUNTIME_DIR</varname> (found
+ below <filename>/run/user</filename>) of the
+ user, which are all writable.</para>
+
+ <para>For unprivileged system processes only
+ <filename>/tmp</filename>,
+ <filename>/var/tmp</filename> and
+ <filename>/dev/shm</filename> are writable. If an
+ unprivileged system process needs a private, writable
+ directory in <filename>/var</filename> or
+ <filename>/run</filename>, it is recommended to either
+ create it before dropping privileges in the daemon
+ code, to create it via
+ <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ fragments during boot, or via the
+ <varname>RuntimeDirectory=</varname> directive of
+ service units (see
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for details).</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Node Types</title>
+
+ <para>Unix file systems support different types of file
+ nodes, including regular files, directories, symlinks,
+ character and block device nodes, sockets and FIFOs.</para>
+
+ <para>It is strongly recommended that
+ <filename>/dev</filename> is the only location below
+ which device nodes shall be placed. Similar,
+ <filename>/run</filename> shall be the only location
+ to place sockets and FIFOs. Regular files,
+ directories and symlinks may be used in all
+ directories.</para>
+ </refsect1>
+
<refsect1>
<title>System Packages</title>
<para>Developers of system packages should follow
strict rules when placing their own files in the file
system. The following table lists recommended
- locations for specific types of files.</para>
+ locations for specific types of files supplied by the
+ vendor.</para>
<table>
- <title>System Package Data Location</title>
+ <title>System Package Vendor Files Locations</title>
<tgroup cols='2' align='left' colsep='1' rowsep='1'>
<colspec colname="directory" />
<colspec colname="purpose" />
<tbody>
<row>
<entry><filename>/usr/bin</filename></entry>
- <entry>Package executables that shall appear in the <varname>$PATH</varname> executable search path, compiled for the primary architecture of the operating system. It is not recommended to place internal binaries or binaries that are not commonly invoked from the shell in this directory, such as daemon binaries. As this directory is shared with most other packages of the system special care should be taken to pick unique names for files placed here, that are unlikely to clash with other package's files.</entry>
+ <entry>Package executables that shall appear in the <varname>$PATH</varname> executable search path, compiled for any of the supported architectures compatible with the operating system. It is not recommended to place internal binaries or binaries that are not commonly invoked from the shell in this directory, such as daemon binaries. As this directory is shared with most other packages of the system special care should be taken to pick unique names for files placed here, that are unlikely to clash with other package's files.</entry>
</row>
<row>
- <entry><filename>$libdir</filename></entry>
+ <entry><filename>/usr/lib/<replaceable>arch-id</replaceable></filename></entry>
<entry>Public shared libraries of the package. As above, be careful with using too generic names, and pick unique names for your libraries to place here to avoid name clashes.</entry>
</row>
<row>
<entry><filename>/usr/lib/<replaceable>package</replaceable></filename></entry>
- <entry>Private static vendor resources of the package, including private binaries and libraries, or any other kind of read-only vendor data.</entry>
+ <entry>Private, static vendor resources of the package, including private binaries and libraries, or any other kind of read-only vendor data.</entry>
</row>
<row>
- <entry><filename>$libdir/<replaceable>package</replaceable></filename></entry>
- <entry>Private other vendor resources of the package that are architecture-specific and cannot be shared between architectures. Note that this generally does not include private exectuables since binaries of a specific architecture may be freely invoked from any other supported system architecture.</entry>
+ <entry><filename>/usr/lib/<replaceable>arch-id</replaceable>/<replaceable>package</replaceable></filename></entry>
+ <entry>Private other vendor resources of the package that are architecture-specific and cannot be shared between architectures. Note that this generally does not include private executables since binaries of a specific architecture may be freely invoked from any other supported system architecture.</entry>
</row>
<row>
<entry><filename>/usr/include/<replaceable>package</replaceable></filename></entry>
<entry>Public C/C++ APIs of public shared libraries of the package.</entry>
</row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <para>Additional static vendor files may be installed
+ in the <filename>/usr/share</filename> hierarchy, to
+ the locations defined by the various relevant
+ specifications.</para>
+
+ <para>During runtime and for local configuration and
+ state additional directories are defined:</para>
+
+ <table>
+ <title>System Package Variable Files Locations</title>
+ <tgroup cols='2' align='left' colsep='1' rowsep='1'>
+ <colspec colname="directory" />
+ <colspec colname="purpose" />
+ <thead>
+ <row>
+ <entry>Directory</entry>
+ <entry>Purpose</entry>
+ </row>
+ </thead>
+ <tbody>
<row>
<entry><filename>/etc/<replaceable>package</replaceable></filename></entry>
<entry>System-specific configuration for the package. It is recommended to default to safe fallbacks if this configuration is missing, if this is possible. Alternatively, a <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry> fragment may be used to copy or symlink the necessary files and directories from <filename>/usr/share/factory</filename> during boot, via the <literal>L</literal> or <literal>C</literal> directives.</entry>
</row>
<row>
<entry><filename>/run/<replaceable>package</replaceable></filename></entry>
- <entry>Runtime data for the package. Packages must be able to create the necessary subdirectories in this tree on their own, since the directory is flushed automatically on boot. Alternatively, a <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry> fragment may be used to create the necessary directories during boot.</entry>
+ <entry>Runtime data for the package. Packages must be able to create the necessary subdirectories in this tree on their own, since the directory is flushed automatically on boot. Alternatively, a <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry> fragment may be used to create the necessary directories during boot. Alternatively, the <varname>RuntimeDirectory=</varname> directive of service units may be used (see <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details.)</entry>
</row>
<row>
<entry><filename>/run/log/<replaceable>package</replaceable></filename></entry>
- <entry>Runtime log data for the package.</entry>
+ <entry>Runtime log data for the package. As above, the package needs to make sure to create this directory if necessary, as it will be flushed on every boot.</entry>
</row>
<row>
<entry><filename>/var/cache/<replaceable>package</replaceable></filename></entry>
- <entry>Persistent cache data of the package. If this directory is flushed the application should work correctly on next invocation, though possibly slowed done due to the need to rebuild any local cache files.</entry>
+ <entry>Persistent cache data of the package. If this directory is flushed the application should work correctly on next invocation, though possibly slowed down due to the need to rebuild any local cache files. The application must be capable of recreating this directory should it be missing and necessary.</entry>
</row>
<row>
<entry><filename>/var/lib/<replaceable>package</replaceable></filename></entry>
</row>
<row>
<entry><filename>/var/log/<replaceable>package</replaceable></filename></entry>
- <entry>Persistent log data of the package.</entry>
+ <entry>Persistent log data of the package. As above, the package should make sure to create this directory if necessary, as it might be missing.</entry>
</row>
<row>
<entry><filename>/var/spool/<replaceable>package</replaceable></filename></entry>
- <entry>Persistent spool/queue data of the package.</entry>
+ <entry>Persistent spool/queue data of the package. As above, the package should make sure to create this directory if necessary, as it might be missing.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </refsect1>
+
+ <refsect1>
+ <title>User Packages</title>
+
+ <para>Programs running in user context should follow
+ strict rules when placing their own files in the
+ user's home directory. The following table lists
+ recommended locations in the home directory for
+ specific types of files supplied by the vendor if the
+ application is installed in the home directory. (Note
+ however, that user applications installed system-wide
+ should follow the rules outlined above regarding
+ placing vendor files.)</para>
+
+ <table>
+ <title>User Package Vendor File Locations</title>
+ <tgroup cols='2' align='left' colsep='1' rowsep='1'>
+ <colspec colname="directory" />
+ <colspec colname="purpose" />
+ <thead>
+ <row>
+ <entry>Directory</entry>
+ <entry>Purpose</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry><filename>~/.local/bin</filename></entry>
+ <entry>Package executables that shall appear in the <varname>$PATH</varname> executable search path. It is not recommended to place internal executables or executables that are not commonly invoked from the shell in this directory, such as daemon executables. As this directory is shared with most other packages of the user special care should be taken to pick unique names for files placed here, that are unlikely to clash with other package's files.</entry>
+ </row>
+ <row>
+ <entry><filename>~/.local/lib/<replaceable>arch-id</replaceable></filename></entry>
+ <entry>Public shared libraries of the package. As above, be careful with using too generic names, and pick unique names for your libraries to place here to avoid name clashes.</entry>
+ </row>
+ <row>
+ <entry><filename>~/.local/lib/<replaceable>package</replaceable></filename></entry>
+ <entry>Private, static vendor resources of the package, compatible with any architecture, or any other kind of read-only vendor data.</entry>
+ </row>
+ <row>
+ <entry><filename>~/.local/lib/<replaceable>arch-id</replaceable>/<replaceable>package</replaceable></filename></entry>
+ <entry>Private other vendor resources of the package that are architecture-specific and cannot be shared between architectures.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <para>Additional static vendor files may be installed
+ in the <filename>~/.local/share</filename> hierarchy,
+ to the locations defined by the various relevant
+ specifications.</para>
+
+ <para>During runtime and for local configuration and
+ state additional directories are defined:</para>
+
+ <table>
+ <title>User Package Variable File Locations</title>
+ <tgroup cols='2' align='left' colsep='1' rowsep='1'>
+ <colspec colname="directory" />
+ <colspec colname="purpose" />
+ <thead>
+ <row>
+ <entry>Directory</entry>
+ <entry>Purpose</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry><filename>~/.config/<replaceable>package</replaceable></filename></entry>
+ <entry>User-specific configuration and state for the package. It is required to default to safe fallbacks if this configuration is missing.</entry>
+ </row>
+ <row>
+ <entry><filename><varname>$XDG_RUNTIME_DIR</varname>/<replaceable>package</replaceable></filename></entry>
+ <entry>User runtime data for the package.</entry>
+ </row>
+ <row>
+ <entry><filename>~/.cache/<replaceable>package</replaceable></filename></entry>
+ <entry>Persistent cache data of the package. If this directory is flushed the application should work correctly on next invocation, though possibly slowed down due to the need to rebuild any local cache files. The application must be capable of recreating this directory should it be missing and necessary.</entry>
</row>
</tbody>
</tgroup>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>hier</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd-boot-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ <citerefentry project='man-pages'><refentrytitle>hier</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-path</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-efi-boot-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
</para>
</refsect1>
~ianmdlvl / elogind.git / blobdiff