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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>file-hierarchy</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><style>
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</style><a href="index.html">Index </a>·
<a href="systemd.directives.html">Directives </a>·
<a href="../python-systemd/index.html">Python </a>·
<a href="../libudev/index.html">libudev </a>·
<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 219</span><hr><div class="refentry"><a name="file-hierarchy"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>file-hierarchy — File system hierarchy overview</p></div><div class="refsect1"><a name="idm140711600162992"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description"></a></h2><p>Operating systems using the
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>
system and service manager are organized based on a file system
hierarchy inspired by UNIX, more specifically the hierarchy
described in the <a class="ulink" href="http://refspecs.linuxfoundation.org/FHS_2.3/fhs-2.3.html" target="_top">File
System Hierarchy</a> specification and
<a href="http://man7.org/linux/man-pages/man7/hier.7.html"><span class="citerefentry"><span class="refentrytitle">hier</span>(7)</span></a>.
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.</p><p>Many of the paths described here are queriable
with the
<a href="systemd-path.html"><span class="citerefentry"><span class="refentrytitle">systemd-path</span>(1)</span></a>
tool.</p></div><div class="refsect1"><a name="idm140711600157744"></a><h2 id="General Structure">General Structure<a class="headerlink" title="Permalink to this headline" href="#General%20Structure"></a></h2><div class="variablelist"><dl class="variablelist"><dt id="/"><span class="term"><code class="filename">/</code></span><a class="headerlink" title="Permalink to this term" href="#/"></a></dt><dd><p>The file system root. Usually writable, but
this is not required. Possibly a temporary file system
("<code class="literal">tmpfs</code>"). Not shared with other hosts
(unless read-only). </p></dd><dt id="/boot"><span class="term"><code class="filename">/boot</code></span><a class="headerlink" title="Permalink to this term" href="#/boot"></a></dt><dd><p>The boot partition used for bringing up the
system. On EFI systems this is possibly the EFI System
Partition, also see
<a href="systemd-efi-boot-generator.html"><span class="citerefentry"><span class="refentrytitle">systemd-efi-boot-generator</span>(8)</span></a>.
This directory is usually strictly local 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 run on physical or emulated hardware that
requires boot loaders.</p></dd><dt id="/etc"><span class="term"><code class="filename">/etc</code></span><a class="headerlink" title="Permalink to this term" href="#/etc"></a></dt><dd><p>System-specific configuration. This directory
may or may not be read-only. Frequently, this directory is
pre-populated with vendor-supplied configuration files, but
applications should not make assumptions about this directory
being fully populated or populated at all, and should fall
back to defaults if configuration is
missing.</p></dd><dt id="/home"><span class="term"><code class="filename">/home</code></span><a class="headerlink" title="Permalink to this term" href="#/home"></a></dt><dd><p>The location for normal user's home
directories. Possibly shared with other systems, and never
read-only. This directory should only be used for normal
users, never for system users. This directory and possibly the
directories contained within it might only become available 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 this directory.
Applications should generally not reference this directory
directly, but via the per-user <code class="varname">$HOME</code>
environment variable, or via the home directory field of the
user database.</p></dd><dt id="/root"><span class="term"><code class="filename">/root</code></span><a class="headerlink" title="Permalink to this term" href="#/root"></a></dt><dd><p>The home directory of the root user. The root
user's home directory is located outside of
<code class="filename">/home</code> in order to make sure the root user
may log in even without <code class="filename">/home</code> being
available and mounted.</p></dd><dt id="/srv"><span class="term"><code class="filename">/srv</code></span><a class="headerlink" title="Permalink to this term" href="#/srv"></a></dt><dd><p>The place to store general server payload,
managed by the administrator. No restrictions are made how
this directory is organized internally. Generally writable,
and possibly shared among systems. This directory might become
available or writable only very late during
boot.</p></dd><dt id="/tmp"><span class="term"><code class="filename">/tmp</code></span><a class="headerlink" title="Permalink to this term" href="#/tmp"></a></dt><dd><p>The place for small temporary files. This
directory is usually mounted as a "<code class="literal">tmpfs</code>"
instance, and should hence not be used for larger files. (Use
<code class="filename">/var/tmp</code> for larger files.) Since the
directory is accessible to other users of the system it is
essential that this directory is only written to with the
<a href="http://man7.org/linux/man-pages/man3/mkstemp.3.html"><span class="citerefentry"><span class="refentrytitle">mkstemp</span>(3)</span></a>,
<a href="http://man7.org/linux/man-pages/man3/mkdtemp.3.html"><span class="citerefentry"><span class="refentrytitle">mkdtemp</span>(3)</span></a>
and related calls. This directory is usually flushed at
boot-up. Also, files that are not accessed within a certain
time are usually automatically deleted. If applications find
the environment variable <code class="varname">$TMPDIR</code> set they
should prefer using the directory specified in it over
directly referencing <code class="filename">/tmp</code> (see
<a href="http://man7.org/linux/man-pages/man7/environ.7.html"><span class="citerefentry"><span class="refentrytitle">environ</span>(7)</span></a>
and
<a class="ulink" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03" target="_top">IEEE
Std 1003.1</a> for details).</p></dd></dl></div></div><div class="refsect1"><a name="idm140711604036048"></a><h2 id="Runtime Data">Runtime Data<a class="headerlink" title="Permalink to this headline" href="#Runtime%20Data"></a></h2><div class="variablelist"><dl class="variablelist"><dt id="/run"><span class="term"><code class="filename">/run</code></span><a class="headerlink" title="Permalink to this term" href="#/run"></a></dt><dd><p>A "<code class="literal">tmpfs</code>" file system for
system packages to place runtime data in. This directory is
flushed on boot, and generally writable for privileged
programs only. Always writable.</p></dd><dt id="/run/log"><span class="term"><code class="filename">/run/log</code></span><a class="headerlink" title="Permalink to this term" href="#/run/log"></a></dt><dd><p>Runtime system logs. System components may
place private logs in this directory. Always writable, even
when <code class="filename">/var/log</code> might not be accessible
yet.</p></dd><dt id="/run/user"><span class="term"><code class="filename">/run/user</code></span><a class="headerlink" title="Permalink to this term" href="#/run/user"></a></dt><dd><p>Contains per-user runtime directories, each
usually individually mounted "<code class="literal">tmpfs</code>"
instances. Always writable, flushed at each reboot and when
the user logs out. User code should not reference this
directory directly, but via the
<code class="varname">$XDG_RUNTIME_DIR</code> environment variable, as
documented in the <a class="ulink" href="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html" target="_top">XDG
Base Directory Specification</a>.</p></dd></dl></div></div><div class="refsect1"><a name="idm140711604019568"></a><h2 id="Vendor-supplied Operating System Resources">Vendor-supplied Operating System Resources<a class="headerlink" title="Permalink to this headline" href="#Vendor-supplied%20Operating%20System%20Resources"></a></h2><div class="variablelist"><dl class="variablelist"><dt id="/usr"><span class="term"><code class="filename">/usr</code></span><a class="headerlink" title="Permalink to this term" href="#/usr"></a></dt><dd><p>Vendor-supplied operating system resources.
Usually read-only, but this is not required. Possibly shared
between multiple hosts. This directory should not be modified
by the administrator, except when installing or removing
vendor-supplied packages.</p></dd><dt id="/usr/bin"><span class="term"><code class="filename">/usr/bin</code></span><a class="headerlink" title="Permalink to this term" href="#/usr/bin"></a></dt><dd><p>Binaries and executables for user commands,
that shall appear in the <code class="varname">$PATH</code> search path.
It is recommended not to place binaries in this directory that
are not useful for invocation from a shell (such as daemon
binaries); these should be placed in a subdirectory of
<code class="filename">/usr/lib</code> instead.</p></dd><dt id="/usr/include"><span class="term"><code class="filename">/usr/include</code></span><a class="headerlink" title="Permalink to this term" href="#/usr/include"></a></dt><dd><p>C and C++ API header files of system
libraries.</p></dd><dt id="/usr/lib"><span class="term"><code class="filename">/usr/lib</code></span><a class="headerlink" title="Permalink to this term" href="#/usr/lib"></a></dt><dd><p>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 <code class="varname">$libdir</code> (see below),
instead.</p></dd><dt id="/usr/lib/arch-id"><span class="term"><code class="filename">/usr/lib/<em class="replaceable"><code>arch-id</code></em></code></span><a class="headerlink" title="Permalink to this term" href="#/usr/lib/arch-id"></a></dt><dd><p>Location for placing dynamic libraries, also
called <code class="varname">$libdir</code>. The architecture identifier
to use is defined on <a class="ulink" href="https://wiki.debian.org/Multiarch/Tuples" target="_top">Multiarch
Architecture Specifiers (Tuples)</a> list. Legacy
locations of <code class="varname">$libdir</code> are
<code class="filename">/usr/lib</code>,
<code class="filename">/usr/lib64</code>. This directory should not be
used for package-specific data, unless this data is
architecture-dependent, too. To query
<code class="varname">$libdir</code> for the primary architecture of the
system, invoke: </p><pre class="programlisting"># pkg-config --variable=libdir
systemd</pre><p> or </p><pre class="programlisting"># systemd-path
system-library-arch</pre><p> </p></dd><dt id="/usr/share"><span class="term"><code class="filename">/usr/share</code></span><a class="headerlink" title="Permalink to this term" href="#/usr/share"></a></dt><dd><p>Resources shared between multiple packages,
such as documentation, man pages, time zone information, fonts
and other resources. Usually, the precise location and format
of files stored below this directory is subject to
specifications that ensure interoperability.</p></dd><dt id="/usr/share/doc"><span class="term"><code class="filename">/usr/share/doc</code></span><a class="headerlink" title="Permalink to this term" href="#/usr/share/doc"></a></dt><dd><p>Documentation for the operating system or
system packages.</p></dd><dt id="/usr/share/factory/etc"><span class="term"><code class="filename">/usr/share/factory/etc</code></span><a class="headerlink" title="Permalink to this term" href="#/usr/share/factory/etc"></a></dt><dd><p>Repository for vendor-supplied default
configuration files. This directory should be populated with
pristine vendor versions of all configuration files that may
be placed in <code class="filename">/etc</code>. This is useful to
compare the local configuration of a system with vendor
defaults and to populate the local configuration with
defaults.</p></dd><dt id="/usr/share/factory/var"><span class="term"><code class="filename">/usr/share/factory/var</code></span><a class="headerlink" title="Permalink to this term" href="#/usr/share/factory/var"></a></dt><dd><p>Similar to
<code class="filename">/usr/share/factory/etc</code> but for vendor
versions of files in the variable, persistent data directory
<code class="filename">/var</code>.</p></dd></dl></div></div><div class="refsect1"><a name="idm140711599078976"></a><h2 id="Persistent Variable System Data">Persistent Variable System Data<a class="headerlink" title="Permalink to this headline" href="#Persistent%20Variable%20System%20Data"></a></h2><div class="variablelist"><dl class="variablelist"><dt id="/var"><span class="term"><code class="filename">/var</code></span><a class="headerlink" title="Permalink to this term" href="#/var"></a></dt><dd><p>Persistent, variable system data. Must be
writable. This directory might be pre-populated with
vendor-supplied data, but applications should be able to
reconstruct necessary files and directories in this
subhierarchy should they be missing, as the system might start
up without this directory being populated. Persistency is
recommended, but optional, to support ephemeral systems. This
directory might become available or writable only very late
during boot. Components that are required to operate during
early boot hence shall not unconditionally rely on this
directory.</p></dd><dt id="/var/cache"><span class="term"><code class="filename">/var/cache</code></span><a class="headerlink" title="Permalink to this term" href="#/var/cache"></a></dt><dd><p>Persistent system cache data. System
components 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.</p></dd><dt id="/var/lib"><span class="term"><code class="filename">/var/lib</code></span><a class="headerlink" title="Permalink to this term" href="#/var/lib"></a></dt><dd><p>Persistent system data. System components may
place private data in this directory.</p></dd><dt id="/var/log"><span class="term"><code class="filename">/var/log</code></span><a class="headerlink" title="Permalink to this term" href="#/var/log"></a></dt><dd><p>Persistent system logs. System components may
place private logs in this directory, though it is recommended
to do most logging via the
<a href="http://man7.org/linux/man-pages/man3/syslog.3.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>
and
<a href="sd_journal_print.html"><span class="citerefentry"><span class="refentrytitle">sd_journal_print</span>(3)</span></a>
calls.</p></dd><dt id="/var/spool"><span class="term"><code class="filename">/var/spool</code></span><a class="headerlink" title="Permalink to this term" href="#/var/spool"></a></dt><dd><p>Persistent system spool data, such as printer
or mail queues.</p></dd><dt id="/var/tmp"><span class="term"><code class="filename">/var/tmp</code></span><a class="headerlink" title="Permalink to this term" href="#/var/tmp"></a></dt><dd><p>The place for larger and persistent temporary
files. In contrast to <code class="filename">/tmp</code> this directory
is usually mounted from a persistent physical file system and
can thus accept larger files. (Use <code class="filename">/tmp</code>
for smaller files.) This directory is generally not flushed at
boot-up, but time-based cleanup of files that have not been
accessed for a certain time is applied. The same security
restrictions as with <code class="filename">/tmp</code> apply, and
hence only
<a href="http://man7.org/linux/man-pages/man3/mkstemp.3.html"><span class="citerefentry"><span class="refentrytitle">mkstemp</span>(3)</span></a>,
<a href="http://man7.org/linux/man-pages/man3/mkdtemp.3.html"><span class="citerefentry"><span class="refentrytitle">mkdtemp</span>(3)</span></a>
or similar calls should be used to make use of this directory.
If applications find the environment variable
<code class="varname">$TMPDIR</code> set they should prefer using the
directory specified in it over directly referencing
<code class="filename">/var/tmp</code> (see
<a href="http://man7.org/linux/man-pages/man7/environ.7.html"><span class="citerefentry"><span class="refentrytitle">environ</span>(7)</span></a>
for details). </p></dd></dl></div></div><div class="refsect1"><a name="idm140711599058352"></a><h2 id="Virtual Kernel and API File Systems">Virtual Kernel and API File Systems<a class="headerlink" title="Permalink to this headline" href="#Virtual%20Kernel%20and%20API%20File%20Systems"></a></h2><div class="variablelist"><dl class="variablelist"><dt id="/dev"><span class="term"><code class="filename">/dev</code></span><a class="headerlink" title="Permalink to this term" href="#/dev"></a></dt><dd><p>The root directory for device nodes. Usually
this directory is mounted as a "<code class="literal">devtmpfs</code>"
instance, but might be of a different type in
sandboxed/containerized setups. This directory is managed
jointly by the kernel and
<a href="systemd-udevd.html"><span class="citerefentry"><span class="refentrytitle">systemd-udevd</span>(8)</span></a>,
and should not be written to by other components. A number of
special purpose virtual file systems might be mounted below
this directory.</p></dd><dt id="/dev/shm"><span class="term"><code class="filename">/dev/shm</code></span><a class="headerlink" title="Permalink to this term" href="#/dev/shm"></a></dt><dd><p>Place for POSIX shared memory segments, as
created via
<a href="shm_open.html"><span class="citerefentry"><span class="refentrytitle">shm_open</span>(3)</span></a>.
This directory is flushed on boot, and is a
"<code class="literal">tmpfs</code>" file system. Since all users have
write access to this directory, special care should be taken
to avoid name clashes and vulnerabilities. For normal users,
shared memory segments in this directory are usually deleted
when the user logs out. Usually it is a better idea to use
memory mapped files in <code class="filename">/run</code> (for system
programs) or <code class="varname">$XDG_RUNTIME_DIR</code> (for user
programs) instead of POSIX shared memory segments, since those
directories are not world-writable and hence not vulnerable to
security-sensitive name clashes.</p></dd><dt id="/proc"><span class="term"><code class="filename">/proc</code></span><a class="headerlink" title="Permalink to this term" href="#/proc"></a></dt><dd><p>A virtual kernel file system exposing the
process list and other functionality. This file system is
mostly an API to interface with the kernel and not a place
where normal files may be stored. For details, see
<a href="http://man7.org/linux/man-pages/man5/proc.5.html"><span class="citerefentry"><span class="refentrytitle">proc</span>(5)</span></a>.
A number of special purpose virtual file systems might be
mounted below this directory.</p></dd><dt id="/proc/sys"><span class="term"><code class="filename">/proc/sys</code></span><a class="headerlink" title="Permalink to this term" href="#/proc/sys"></a></dt><dd><p>A hierarchy below <code class="filename">/proc</code>
that exposes a number of kernel tunables. The primary way to
configure the settings in this API file tree is via
<a href="sysctl.d.html"><span class="citerefentry"><span class="refentrytitle">sysctl.d</span>(5)</span></a>
files. In sandboxed/containerized setups this directory is
generally mounted read-only.</p></dd><dt id="/sys"><span class="term"><code class="filename">/sys</code></span><a class="headerlink" title="Permalink to this term" href="#/sys"></a></dt><dd><p>A virtual kernel file system exposing
discovered devices and other functionality. This file system
is mostly an API to interface with the kernel and not a place
where normal files may be stored. In sandboxed/containerized
setups this directory is generally mounted read-only. A number
of special purpose virtual file systems might be mounted below
this directory.</p></dd></dl></div></div><div class="refsect1"><a name="idm140711599040192"></a><h2 id="Compatibility Symlinks">Compatibility Symlinks<a class="headerlink" title="Permalink to this headline" href="#Compatibility%20Symlinks"></a></h2><div class="variablelist"><dl class="variablelist"><dt id="/bin"><span class="term"><code class="filename">/bin</code>, </span><span class="term"><code class="filename">/sbin</code>, </span><span class="term"><code class="filename">/usr/sbin</code></span><a class="headerlink" title="Permalink to this term" href="#/bin"></a></dt><dd><p>These compatibility symlinks point to
<code class="filename">/usr/bin</code>, ensuring that scripts and
binaries referencing these legacy paths correctly find their
binaries.</p></dd><dt id="/lib"><span class="term"><code class="filename">/lib</code></span><a class="headerlink" title="Permalink to this term" href="#/lib"></a></dt><dd><p>This compatibility symlink points to
<code class="filename">/usr/lib</code>, ensuring that programs
referencing this legacy path correctly find their
resources.</p></dd><dt id="/lib64"><span class="term"><code class="filename">/lib64</code></span><a class="headerlink" title="Permalink to this term" href="#/lib64"></a></dt><dd><p>On some architecture ABIs this compatibility
symlink points to <code class="varname">$libdir</code>, ensuring that
binaries referencing this legacy path correctly find their
dynamic loader. This symlink only exists on architectures
whose ABI places the dynamic loader in this
path.</p></dd><dt id="/var/run"><span class="term"><code class="filename">/var/run</code></span><a class="headerlink" title="Permalink to this term" href="#/var/run"></a></dt><dd><p>This compatibility symlink points to
<code class="filename">/run</code>, ensuring that programs referencing
this legacy path correctly find their runtime
data.</p></dd></dl></div></div><div class="refsect1"><a name="idm140711599028016"></a><h2 id="Home Directory">Home Directory<a class="headerlink" title="Permalink to this headline" href="#Home%20Directory"></a></h2><p>User applications may want to place files and directories in
the user's home directory. They should follow the following basic
structure. Note that some of these directories are also
standardized (though more weakly) by the <a class="ulink" href="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html" target="_top">XDG
Base Directory Specification</a>. Additional locations for
high-level user resources are defined by <a class="ulink" href="http://www.freedesktop.org/wiki/Software/xdg-user-dirs/" target="_top">xdg-user-dirs</a>.</p><div class="variablelist"><dl class="variablelist"><dt id="~/.cache"><span class="term"><code class="filename">~/.cache</code></span><a class="headerlink" title="Permalink to this term" href="#~/.cache"></a></dt><dd><p>Persistent user cache data. User programs may
place non-essential data in this directory. Flushing this
directory should have no effect on operation of programs,
except for increased runtimes necessary to rebuild these
caches. If an application finds
<code class="varname">$XDG_CACHE_HOME</code> set is should use the
directory specified in it instead of this
directory.</p></dd><dt id="~/.config"><span class="term"><code class="filename">~/.config</code></span><a class="headerlink" title="Permalink to this term" href="#~/.config"></a></dt><dd><p>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 <code class="varname">$XDG_CONFIG_HOME</code> set is
should use the directory specified in it instead of this
directory.</p></dd><dt id="~/.local/bin"><span class="term"><code class="filename">~/.local/bin</code></span><a class="headerlink" title="Permalink to this term" href="#~/.local/bin"></a></dt><dd><p>Executables that shall appear in the user's
<code class="varname">$PATH</code> 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 <code class="filename">~/.local/lib</code> 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.</p></dd><dt id="~/.local/lib"><span class="term"><code class="filename">~/.local/lib</code></span><a class="headerlink" title="Permalink to this term" href="#~/.local/lib"></a></dt><dd><p>Static, private vendor data that is compatible
with all architectures.</p></dd><dt id="~/.local/lib/arch-id"><span class="term"><code class="filename">~/.local/lib/<em class="replaceable"><code>arch-id</code></em></code></span><a class="headerlink" title="Permalink to this term" href="#~/.local/lib/arch-id"></a></dt><dd><p>Location for placing public dynamic libraries.
The architecture identifier to use, is defined on <a class="ulink" href="https://wiki.debian.org/Multiarch/Tuples" target="_top">Multiarch
Architecture Specifiers (Tuples)</a>
list.</p></dd><dt id="~/.local/share"><span class="term"><code class="filename">~/.local/share</code></span><a class="headerlink" title="Permalink to this term" href="#~/.local/share"></a></dt><dd><p>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 <code class="varname">$XDG_DATA_HOME</code> set is should use the
directory specified in it instead of this
directory.</p></dd></dl></div></div><div class="refsect1"><a name="idm140711599009984"></a><h2 id="Unprivileged Write Access">Unprivileged Write Access<a class="headerlink" title="Permalink to this headline" href="#Unprivileged%20Write%20Access"></a></h2><p>Unprivileged processes generally lack write access to most
of the hierarchy.</p><p>The exceptions for normal users are
<code class="filename">/tmp</code>,
<code class="filename">/var/tmp</code>,
<code class="filename">/dev/shm</code>, as well as the home directory
<code class="varname">$HOME</code> (usually found below
<code class="filename">/home</code>) and the runtime directory
<code class="varname">$XDG_RUNTIME_DIR</code> (found below
<code class="filename">/run/user</code>) of the user, which are all
writable.</p><p>For unprivileged system processes only
<code class="filename">/tmp</code>,
<code class="filename">/var/tmp</code> and
<code class="filename">/dev/shm</code> are writable. If an
unprivileged system process needs a private, writable directory in
<code class="filename">/var</code> or <code class="filename">/run</code>, it is
recommended to either create it before dropping privileges in the
daemon code, to create it via
<a href="tmpfiles.d.html"><span class="citerefentry"><span class="refentrytitle">tmpfiles.d</span>(5)</span></a>
fragments during boot, or via the
<code class="varname">RuntimeDirectory=</code> directive of service units
(see
<a href="systemd.unit.html"><span class="citerefentry"><span class="refentrytitle">systemd.unit</span>(5)</span></a>
for details).</p></div><div class="refsect1"><a name="idm140711598998800"></a><h2 id="Node Types">Node Types<a class="headerlink" title="Permalink to this headline" href="#Node%20Types"></a></h2><p>Unix file systems support different types of file nodes,
including regular files, directories, symlinks, character and
block device nodes, sockets and FIFOs.</p><p>It is strongly recommended that <code class="filename">/dev</code> is
the only location below which device nodes shall be placed.
Similar, <code class="filename">/run</code> shall be the only location to
place sockets and FIFOs. Regular files, directories and symlinks
may be used in all directories.</p></div><div class="refsect1"><a name="idm140711598995600"></a><h2 id="System Packages">System Packages<a class="headerlink" title="Permalink to this headline" href="#System%20Packages"></a></h2><p>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
supplied by the vendor.</p><div class="table"><a name="idm140711598994336"></a><p class="title"><b>Table 1. System Package Vendor Files Locations</b></p><div class="table-contents"><table summary="System Package Vendor Files Locations" border="1"><colgroup><col align="left" class="directory"><col align="left" class="purpose"></colgroup><thead><tr><th align="left">Directory</th><th align="left">Purpose</th></tr></thead><tbody><tr><td align="left"><code class="filename">/usr/bin</code></td><td align="left">Package executables that shall appear in the <code class="varname">$PATH</code> 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.</td></tr><tr><td align="left"><code class="filename">/usr/lib/<em class="replaceable"><code>arch-id</code></em></code></td><td align="left">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.</td></tr><tr><td align="left"><code class="filename">/usr/lib/<em class="replaceable"><code>package</code></em></code></td><td align="left">Private, static vendor resources of the package, including private binaries and libraries, or any other kind of read-only vendor data.</td></tr><tr><td align="left"><code class="filename">/usr/lib/<em class="replaceable"><code>arch-id</code></em>/<em class="replaceable"><code>package</code></em></code></td><td align="left">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.</td></tr><tr><td align="left"><code class="filename">/usr/include/<em class="replaceable"><code>package</code></em></code></td><td align="left">Public C/C++ APIs of public shared libraries of the package.</td></tr></tbody></table></div></div><br class="table-break"><p>Additional static vendor files may be installed in the
<code class="filename">/usr/share</code> hierarchy, to the locations
defined by the various relevant specifications.</p><p>During runtime and for local configuration and state
additional directories are defined:</p><div class="table"><a name="idm140711598977056"></a><p class="title"><b>Table 2. System Package Variable Files Locations</b></p><div class="table-contents"><table summary="System Package Variable Files Locations" border="1"><colgroup><col align="left" class="directory"><col align="left" class="purpose"></colgroup><thead><tr><th align="left">Directory</th><th align="left">Purpose</th></tr></thead><tbody><tr><td align="left"><code class="filename">/etc/<em class="replaceable"><code>package</code></em></code></td><td align="left">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 <a href="tmpfiles.d.html"><span class="citerefentry"><span class="refentrytitle">tmpfiles.d</span>(5)</span></a> fragment may be used to copy or symlink the necessary files and directories from <code class="filename">/usr/share/factory</code> during boot, via the "<code class="literal">L</code>" or "<code class="literal">C</code>" directives.</td></tr><tr><td align="left"><code class="filename">/run/<em class="replaceable"><code>package</code></em></code></td><td align="left">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 <a href="tmpfiles.d.html"><span class="citerefentry"><span class="refentrytitle">tmpfiles.d</span>(5)</span></a> fragment may be used to create the necessary directories during boot. Alternatively, the <code class="varname">RuntimeDirectory=</code> directive of service units may be used (see <a href="systemd.unit.html"><span class="citerefentry"><span class="refentrytitle">systemd.unit</span>(5)</span></a> for details.)</td></tr><tr><td align="left"><code class="filename">/run/log/<em class="replaceable"><code>package</code></em></code></td><td align="left">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.</td></tr><tr><td align="left"><code class="filename">/var/cache/<em class="replaceable"><code>package</code></em></code></td><td align="left">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.</td></tr><tr><td align="left"><code class="filename">/var/lib/<em class="replaceable"><code>package</code></em></code></td><td align="left">Persistent private data of the package. This is the primary place to put persistent data that does not fall into the other categories listed. Packages should be able to create the necessary subdirectories in this tree on their own, since the directory might be missing on boot. Alternatively, a <a href="tmpfiles.d.html"><span class="citerefentry"><span class="refentrytitle">tmpfiles.d</span>(5)</span></a> fragment may be used to create the necessary directories during boot.</td></tr><tr><td align="left"><code class="filename">/var/log/<em class="replaceable"><code>package</code></em></code></td><td align="left">Persistent log data of the package. As above, the package should make sure to create this directory if necessary, as it might be missing.</td></tr><tr><td align="left"><code class="filename">/var/spool/<em class="replaceable"><code>package</code></em></code></td><td align="left">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.</td></tr></tbody></table></div></div><br class="table-break"></div><div class="refsect1"><a name="idm140711598952368"></a><h2 id="User Packages">User Packages<a class="headerlink" title="Permalink to this headline" href="#User%20Packages"></a></h2><p>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.)</p><div class="table"><a name="idm140711598950880"></a><p class="title"><b>Table 3. User Package Vendor File Locations</b></p><div class="table-contents"><table summary="User Package Vendor File Locations" border="1"><colgroup><col align="left" class="directory"><col align="left" class="purpose"></colgroup><thead><tr><th align="left">Directory</th><th align="left">Purpose</th></tr></thead><tbody><tr><td align="left"><code class="filename">~/.local/bin</code></td><td align="left">Package executables that shall appear in the <code class="varname">$PATH</code> 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.</td></tr><tr><td align="left"><code class="filename">~/.local/lib/<em class="replaceable"><code>arch-id</code></em></code></td><td align="left">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.</td></tr><tr><td align="left"><code class="filename">~/.local/lib/<em class="replaceable"><code>package</code></em></code></td><td align="left">Private, static vendor resources of the package, compatible with any architecture, or any other kind of read-only vendor data.</td></tr><tr><td align="left"><code class="filename">~/.local/lib/<em class="replaceable"><code>arch-id</code></em>/<em class="replaceable"><code>package</code></em></code></td><td align="left">Private other vendor resources of the package that are architecture-specific and cannot be shared between architectures.</td></tr></tbody></table></div></div><br class="table-break"><p>Additional static vendor files may be installed in the
<code class="filename">~/.local/share</code> hierarchy, to the locations
defined by the various relevant specifications.</p><p>During runtime and for local configuration and state
additional directories are defined:</p><div class="table"><a name="idm140711598935680"></a><p class="title"><b>Table 4. User Package Variable File Locations</b></p><div class="table-contents"><table summary="User Package Variable File Locations" border="1"><colgroup><col align="left" class="directory"><col align="left" class="purpose"></colgroup><thead><tr><th align="left">Directory</th><th align="left">Purpose</th></tr></thead><tbody><tr><td align="left"><code class="filename">~/.config/<em class="replaceable"><code>package</code></em></code></td><td align="left">User-specific configuration and state for the package. It is required to default to safe fallbacks if this configuration is missing.</td></tr><tr><td align="left"><code class="filename"><code class="varname">$XDG_RUNTIME_DIR</code>/<em class="replaceable"><code>package</code></em></code></td><td align="left">User runtime data for the package.</td></tr><tr><td align="left"><code class="filename">~/.cache/<em class="replaceable"><code>package</code></em></code></td><td align="left">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.</td></tr></tbody></table></div></div><br class="table-break"></div><div class="refsect1"><a name="idm140711598924480"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also"></a></h2><p>
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
<a href="http://man7.org/linux/man-pages/man7/hier.7.html"><span class="citerefentry"><span class="refentrytitle">hier</span>(7)</span></a>,
<a href="systemd-path.html"><span class="citerefentry"><span class="refentrytitle">systemd-path</span>(1)</span></a>,
<a href="systemd-efi-boot-generator.html"><span class="citerefentry"><span class="refentrytitle">systemd-efi-boot-generator</span>(8)</span></a>,
<a href="sysctl.d.html"><span class="citerefentry"><span class="refentrytitle">sysctl.d</span>(5)</span></a>,
<a href="tmpfiles.d.html"><span class="citerefentry"><span class="refentrytitle">tmpfiles.d</span>(5)</span></a>,
<a href="http://linux.die.net/man/1/pkg-config"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>,
<a href="systemd.unit.html"><span class="citerefentry"><span class="refentrytitle">systemd.unit</span>(5)</span></a>
</p></div></div></body></html>
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