man/file-hierarchy.xml

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  23
  24 <refentry id="file-hierarchy">
  25
  26   <refentryinfo>
  27     <title>file-hierarchy</title>
  28     <productname>systemd</productname>
  29
  30     <authorgroup>
  31       <author>
  32         <contrib>Developer</contrib>
  33         <firstname>Lennart</firstname>
  34         <surname>Poettering</surname>
  35         <email>lennart@poettering.net</email>
  36       </author>
  37     </authorgroup>
  38   </refentryinfo>
  39
  40   <refmeta>
  41     <refentrytitle>file-hierarchy</refentrytitle>
  42     <manvolnum>7</manvolnum>
  43   </refmeta>
  44
  45   <refnamediv>
  46     <refname>file-hierarchy</refname>
  47     <refpurpose>File system hierarchy overview</refpurpose>
  48   </refnamediv>
  49
  50   <refsect1>
  51     <title>Description</title>
  52
  53     <para>Operating systems using the
  54     <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  55     system and service manager are organized based on a file system
  56     hierarchy inspired by UNIX, more specifically the hierarchy
  57     described in the <ulink
  58     url="http://refspecs.linuxfoundation.org/FHS_2.3/fhs-2.3.html">File
  59     System Hierarchy</ulink> specification and
  60     <citerefentry project='man-pages'><refentrytitle>hier</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
  61     This manual page describes a more minimal, modernized subset of
  62     these specifications that defines more strictly the suggestions
  63     and restrictions systemd makes on the file system
  64     hierarchy.</para>
  65
  66     <para>Many of the paths described here are queriable
  67     with the
  68     <citerefentry><refentrytitle>systemd-path</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  69     tool.</para>
  70   </refsect1>
  71
  72   <refsect1>
  73     <title>General Structure</title>
  74
  75     <variablelist>
  76       <varlistentry>
  77         <term><filename>/</filename></term>
  78         <listitem><para>The file system root. Usually writable, but
  79         this is not required. Possibly a temporary file system
  80         (<literal>tmpfs</literal>). Not shared with other hosts
  81         (unless read-only). </para></listitem>
  82       </varlistentry>
  83
  84       <varlistentry>
  85         <term><filename>/boot</filename></term>
  86         <listitem><para>The boot partition used for bringing up the
  87         system. On EFI systems, this is possibly the EFI System
  88         Partition, also see
  89         <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
  90         This directory is usually strictly local to the host, and
  91         should be considered read-only, except when a new kernel or
  92         boot loader is installed. This directory only exists on
  93         systems that run on physical or emulated hardware that
  94         requires boot loaders.</para></listitem>
  95       </varlistentry>
  96
  97       <varlistentry>
  98         <term><filename>/etc</filename></term>
  99         <listitem><para>System-specific configuration. This directory
 100         may or may not be read-only. Frequently, this directory is
 101         pre-populated with vendor-supplied configuration files, but
 102         applications should not make assumptions about this directory
 103         being fully populated or populated at all, and should fall
 104         back to defaults if configuration is
 105         missing.</para></listitem>
 106       </varlistentry>
 107
 108       <varlistentry>
 109         <term><filename>/home</filename></term>
 110         <listitem><para>The location for normal user's home
 111         directories. Possibly shared with other systems, and never
 112         read-only. This directory should only be used for normal
 113         users, never for system users. This directory and possibly the
 114         directories contained within it might only become available or
 115         writable in late boot or even only after user authentication.
 116         This directory might be placed on limited-functionality
 117         network file systems, hence applications should not assume the
 118         full set of file API is available on this directory.
 119         Applications should generally not reference this directory
 120         directly, but via the per-user <varname>$HOME</varname>
 121         environment variable, or via the home directory field of the
 122         user database.</para></listitem>
 123       </varlistentry>
 124
 125       <varlistentry>
 126         <term><filename>/root</filename></term>
 127         <listitem><para>The home directory of the root user. The root
 128         user's home directory is located outside of
 129         <filename>/home</filename> in order to make sure the root user
 130         may log in even without <filename>/home</filename> being
 131         available and mounted.</para></listitem>
 132       </varlistentry>
 133
 134       <varlistentry>
 135         <term><filename>/srv</filename></term>
 136         <listitem><para>The place to store general server payload,
 137         managed by the administrator. No restrictions are made how
 138         this directory is organized internally. Generally writable,
 139         and possibly shared among systems. This directory might become
 140         available or writable only very late during
 141         boot.</para></listitem>
 142       </varlistentry>
 143
 144       <varlistentry>
 145         <term><filename>/tmp</filename></term>
 146         <listitem><para>The place for small temporary files. This
 147         directory is usually mounted as a <literal>tmpfs</literal>
 148         instance, and should hence not be used for larger files. (Use
 149         <filename>/var/tmp</filename> for larger files.) Since the
 150         directory is accessible to other users of the system, it is
 151         essential that this directory is only written to with the
 152         <citerefentry project='man-pages'><refentrytitle>mkstemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 153         <citerefentry project='man-pages'><refentrytitle>mkdtemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 154         and related calls. This directory is usually flushed at
 155         boot-up. Also, files that are not accessed within a certain
 156         time are usually automatically deleted. If applications find
 157         the environment variable <varname>$TMPDIR</varname> set, they
 158         should prefer using the directory specified in it over
 159         directly referencing <filename>/tmp</filename> (see
 160         <citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 161         and
 162         <ulink url="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03">IEEE
 163         Std 1003.1</ulink> for details).</para></listitem>
 164       </varlistentry>
 165
 166     </variablelist>
 167   </refsect1>
 168
 169   <refsect1>
 170     <title>Runtime Data</title>
 171
 172     <variablelist>
 173       <varlistentry>
 174         <term><filename>/run</filename></term>
 175         <listitem><para>A <literal>tmpfs</literal> file system for
 176         system packages to place runtime data in. This directory is
 177         flushed on boot, and generally writable for privileged
 178         programs only. Always writable.</para></listitem>
 179       </varlistentry>
 180
 181       <varlistentry>
 182         <term><filename>/run/log</filename></term>
 183         <listitem><para>Runtime system logs. System components may
 184         place private logs in this directory. Always writable, even
 185         when <filename>/var/log</filename> might not be accessible
 186         yet.</para></listitem>
 187       </varlistentry>
 188
 189       <varlistentry>
 190         <term><filename>/run/user</filename></term>
 191         <listitem><para>Contains per-user runtime directories, each
 192         usually individually mounted <literal>tmpfs</literal>
 193         instances. Always writable, flushed at each reboot and when
 194         the user logs out. User code should not reference this
 195         directory directly, but via the
 196         <varname>$XDG_RUNTIME_DIR</varname> environment variable, as
 197         documented in the <ulink
 198         url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
 199         Base Directory Specification</ulink>.</para></listitem>
 200       </varlistentry>
 201     </variablelist>
 202   </refsect1>
 203
 204   <refsect1>
 205     <title>Vendor-supplied Operating System Resources</title>
 206
 207     <variablelist>
 208
 209       <varlistentry>
 210         <term><filename>/usr</filename></term>
 211         <listitem><para>Vendor-supplied operating system resources.
 212         Usually read-only, but this is not required. Possibly shared
 213         between multiple hosts. This directory should not be modified
 214         by the administrator, except when installing or removing
 215         vendor-supplied packages.</para></listitem>
 216       </varlistentry>
 217
 218       <varlistentry>
 219         <term><filename>/usr/bin</filename></term>
 220         <listitem><para>Binaries and executables for user commands
 221         that shall appear in the <varname>$PATH</varname> search path.
 222         It is recommended not to place binaries in this directory that
 223         are not useful for invocation from a shell (such as daemon
 224         binaries); these should be placed in a subdirectory of
 225         <filename>/usr/lib</filename> instead.</para></listitem>
 226       </varlistentry>
 227
 228       <varlistentry>
 229         <term><filename>/usr/include</filename></term>
 230         <listitem><para>C and C++ API header files of system
 231         libraries.</para></listitem>
 232       </varlistentry>
 233
 234       <varlistentry>
 235         <term><filename>/usr/lib</filename></term>
 236         <listitem><para>Static, private vendor data that is compatible
 237         with all architectures (though not necessarily
 238         architecture-independent). Note that this includes internal
 239         executables or other binaries that are not regularly invoked
 240         from a shell. Such binaries may be for any architecture
 241         supported by the system. Do not place public libraries in this
 242         directory, use <varname>$libdir</varname> (see below),
 243         instead.</para></listitem>
 244       </varlistentry>
 245
 246       <varlistentry>
 247         <term><filename>/usr/lib/<replaceable>arch-id</replaceable></filename></term>
 248         <listitem><para>Location for placing dynamic libraries into, also
 249         called <varname>$libdir</varname>. The architecture identifier
 250         to use is defined on <ulink
 251         url="https://wiki.debian.org/Multiarch/Tuples">Multiarch
 252         Architecture Specifiers (Tuples)</ulink> list. Legacy
 253         locations of <varname>$libdir</varname> are
 254         <filename>/usr/lib</filename>,
 255         <filename>/usr/lib64</filename>. This directory should not be
 256         used for package-specific data, unless this data is
 257         architecture-dependent, too. To query
 258         <varname>$libdir</varname> for the primary architecture of the
 259         system, invoke:
 260         <programlisting># systemd-path system-library-arch</programlisting></para></listitem>
 261
 262       </varlistentry>
 263
 264       <varlistentry>
 265         <term><filename>/usr/share</filename></term>
 266         <listitem><para>Resources shared between multiple packages,
 267         such as documentation, man pages, time zone information, fonts
 268         and other resources. Usually, the precise location and format
 269         of files stored below this directory is subject to
 270         specifications that ensure interoperability.</para></listitem>
 271       </varlistentry>
 272
 273       <varlistentry>
 274         <term><filename>/usr/share/doc</filename></term>
 275         <listitem><para>Documentation for the operating system or
 276         system packages.</para></listitem>
 277       </varlistentry>
 278
 279       <varlistentry>
 280         <term><filename>/usr/share/factory/etc</filename></term>
 281         <listitem><para>Repository for vendor-supplied default
 282         configuration files. This directory should be populated with
 283         pristine vendor versions of all configuration files that may
 284         be placed in <filename>/etc</filename>. This is useful to
 285         compare the local configuration of a system with vendor
 286         defaults and to populate the local configuration with
 287         defaults.</para></listitem>
 288       </varlistentry>
 289
 290       <varlistentry>
 291         <term><filename>/usr/share/factory/var</filename></term>
 292
 293         <listitem><para>Similar to
 294         <filename>/usr/share/factory/etc</filename>, but for vendor
 295         versions of files in the variable, persistent data directory
 296         <filename>/var</filename>.</para></listitem>
 297
 298       </varlistentry>
 299     </variablelist>
 300   </refsect1>
 301
 302   <refsect1>
 303     <title>Persistent Variable System Data</title>
 304
 305     <variablelist>
 306       <varlistentry>
 307         <term><filename>/var</filename></term>
 308         <listitem><para>Persistent, variable system data. Must be
 309         writable. This directory might be pre-populated with
 310         vendor-supplied data, but applications should be able to
 311         reconstruct necessary files and directories in this
 312         subhierarchy should they be missing, as the system might start
 313         up without this directory being populated. Persistency is
 314         recommended, but optional, to support ephemeral systems. This
 315         directory might become available or writable only very late
 316         during boot. Components that are required to operate during
 317         early boot hence shall not unconditionally rely on this
 318         directory.</para></listitem>
 319       </varlistentry>
 320
 321       <varlistentry>
 322         <term><filename>/var/cache</filename></term>
 323         <listitem><para>Persistent system cache data. System
 324         components may place non-essential data in this directory.
 325         Flushing this directory should have no effect on operation of
 326         programs, except for increased runtimes necessary to rebuild
 327         these caches.</para></listitem>
 328       </varlistentry>
 329
 330       <varlistentry>
 331         <term><filename>/var/lib</filename></term>
 332         <listitem><para>Persistent system data. System components may
 333         place private data in this directory.</para></listitem>
 334       </varlistentry>
 335
 336       <varlistentry>
 337         <term><filename>/var/log</filename></term>
 338         <listitem><para>Persistent system logs. System components may
 339         place private logs in this directory, though it is recommended
 340         to do most logging via the
 341         <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 342         and
 343         <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 344         calls.</para></listitem>
 345       </varlistentry>
 346
 347       <varlistentry>
 348         <term><filename>/var/spool</filename></term>
 349         <listitem><para>Persistent system spool data, such as printer
 350         or mail queues.</para></listitem>
 351       </varlistentry>
 352
 353       <varlistentry>
 354         <term><filename>/var/tmp</filename></term>
 355         <listitem><para>The place for larger and persistent temporary
 356         files. In contrast to <filename>/tmp</filename>, this directory
 357         is usually mounted from a persistent physical file system and
 358         can thus accept larger files. (Use <filename>/tmp</filename>
 359         for smaller files.) This directory is generally not flushed at
 360         boot-up, but time-based cleanup of files that have not been
 361         accessed for a certain time is applied. The same security
 362         restrictions as with <filename>/tmp</filename> apply, and
 363         hence only
 364         <citerefentry project='man-pages'><refentrytitle>mkstemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 365         <citerefentry project='man-pages'><refentrytitle>mkdtemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 366         or similar calls should be used to make use of this directory.
 367         If applications find the environment variable
 368         <varname>$TMPDIR</varname> set, they should prefer using the
 369         directory specified in it over directly referencing
 370         <filename>/var/tmp</filename> (see
 371         <citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 372         for details). </para></listitem>
 373       </varlistentry>
 374
 375     </variablelist>
 376   </refsect1>
 377
 378   <refsect1>
 379     <title>Virtual Kernel and API File Systems</title>
 380
 381     <variablelist>
 382       <varlistentry>
 383         <term><filename>/dev</filename></term>
 384         <listitem><para>The root directory for device nodes. Usually,
 385         this directory is mounted as a <literal>devtmpfs</literal>
 386         instance, but might be of a different type in
 387         sandboxed/containerized setups. This directory is managed
 388         jointly by the kernel and
 389         <citerefentry><refentrytitle>systemd-udevd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 390         and should not be written to by other components. A number of
 391         special purpose virtual file systems might be mounted below
 392         this directory.</para></listitem>
 393       </varlistentry>
 394
 395       <varlistentry>
 396         <term><filename>/dev/shm</filename></term>
 397         <listitem><para>Place for POSIX shared memory segments, as
 398         created via
 399         <citerefentry project='die-net'><refentrytitle>shm_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 400         This directory is flushed on boot, and is a
 401         <literal>tmpfs</literal> file system. Since all users have
 402         write access to this directory, special care should be taken
 403         to avoid name clashes and vulnerabilities. For normal users,
 404         shared memory segments in this directory are usually deleted
 405         when the user logs out. Usually, it is a better idea to use
 406         memory mapped files in <filename>/run</filename> (for system
 407         programs) or <varname>$XDG_RUNTIME_DIR</varname> (for user
 408         programs) instead of POSIX shared memory segments, since these
 409         directories are not world-writable and hence not vulnerable to
 410         security-sensitive name clashes.</para></listitem>
 411       </varlistentry>
 412
 413       <varlistentry>
 414         <term><filename>/proc</filename></term>
 415         <listitem><para>A virtual kernel file system exposing the
 416         process list and other functionality. This file system is
 417         mostly an API to interface with the kernel and not a place
 418         where normal files may be stored. For details, see
 419         <citerefentry project='man-pages'><refentrytitle>proc</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 420         A number of special purpose virtual file systems might be
 421         mounted below this directory.</para></listitem>
 422       </varlistentry>
 423
 424       <varlistentry>
 425         <term><filename>/proc/sys</filename></term>
 426         <listitem><para>A hierarchy below <filename>/proc</filename>
 427         that exposes a number of kernel tunables. The primary way to
 428         configure the settings in this API file tree is via
 429         <citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 430         files. In sandboxed/containerized setups, this directory is
 431         generally mounted read-only.</para></listitem>
 432       </varlistentry>
 433
 434       <varlistentry>
 435         <term><filename>/sys</filename></term>
 436         <listitem><para>A virtual kernel file system exposing
 437         discovered devices and other functionality. This file system
 438         is mostly an API to interface with the kernel and not a place
 439         where normal files may be stored. In sandboxed/containerized
 440         setups, this directory is generally mounted read-only. A number
 441         of special purpose virtual file systems might be mounted below
 442         this directory.</para></listitem>
 443       </varlistentry>
 444
 445     </variablelist>
 446   </refsect1>
 447
 448   <refsect1>
 449     <title>Compatibility Symlinks</title>
 450
 451     <variablelist>
 452       <varlistentry>
 453         <term><filename>/bin</filename></term>
 454         <term><filename>/sbin</filename></term>
 455         <term><filename>/usr/sbin</filename></term>
 456
 457         <listitem><para>These compatibility symlinks point to
 458         <filename>/usr/bin</filename>, ensuring that scripts and
 459         binaries referencing these legacy paths correctly find their
 460         binaries.</para></listitem>
 461       </varlistentry>
 462
 463       <varlistentry>
 464         <term><filename>/lib</filename></term>
 465
 466         <listitem><para>This compatibility symlink points to
 467         <filename>/usr/lib</filename>, ensuring that programs
 468         referencing this legacy path correctly find their
 469         resources.</para></listitem>
 470       </varlistentry>
 471
 472       <varlistentry>
 473         <term><filename>/lib64</filename></term>
 474
 475         <listitem><para>On some architecture ABIs, this compatibility
 476         symlink points to <varname>$libdir</varname>, ensuring that
 477         binaries referencing this legacy path correctly find their
 478         dynamic loader. This symlink only exists on architectures
 479         whose ABI places the dynamic loader in this
 480         path.</para></listitem>
 481       </varlistentry>
 482
 483       <varlistentry>
 484         <term><filename>/var/run</filename></term>
 485
 486         <listitem><para>This compatibility symlink points to
 487         <filename>/run</filename>, ensuring that programs referencing
 488         this legacy path correctly find their runtime
 489         data.</para></listitem>
 490       </varlistentry>
 491
 492     </variablelist>
 493   </refsect1>
 494
 495   <refsect1>
 496     <title>Home Directory</title>
 497
 498     <para>User applications may want to place files and directories in
 499     the user's home directory. They should follow the following basic
 500     structure. Note that some of these directories are also
 501     standardized (though more weakly) by the <ulink
 502     url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
 503     Base Directory Specification</ulink>. Additional locations for
 504     high-level user resources are defined by <ulink
 505     url="http://www.freedesktop.org/wiki/Software/xdg-user-dirs/">xdg-user-dirs</ulink>.</para>
 506
 507     <variablelist>
 508       <varlistentry>
 509         <term><filename>~/.cache</filename></term>
 510
 511         <listitem><para>Persistent user cache data. User programs may
 512         place non-essential data in this directory. Flushing this
 513         directory should have no effect on operation of programs,
 514         except for increased runtimes necessary to rebuild these
 515         caches. If an application finds
 516         <varname>$XDG_CACHE_HOME</varname> set, it should use the
 517         directory specified in it instead of this
 518         directory.</para></listitem>
 519       </varlistentry>
 520
 521       <varlistentry>
 522         <term><filename>~/.config</filename></term>
 523
 524         <listitem><para>Application configuration and state. When a
 525         new user is created, this directory will be empty or not exist
 526         at all. Applications should fall back to defaults should their
 527         configuration or state in this directory be missing. If an
 528         application finds <varname>$XDG_CONFIG_HOME</varname> set, it
 529         should use the directory specified in it instead of this
 530         directory.</para></listitem>
 531       </varlistentry>
 532
 533       <varlistentry>
 534         <term><filename>~/.local/bin</filename></term>
 535
 536         <listitem><para>Executables that shall appear in the user's
 537         <varname>$PATH</varname> search path. It is recommended not to
 538         place executables in this directory that are not useful for
 539         invocation from a shell; these should be placed in a
 540         subdirectory of <filename>~/.local/lib</filename> instead.
 541         Care should be taken when placing architecture-dependent
 542         binaries in this place, which might be problematic if the home
 543         directory is shared between multiple hosts with different
 544         architectures.</para></listitem>
 545       </varlistentry>
 546
 547       <varlistentry>
 548         <term><filename>~/.local/lib</filename></term>
 549
 550         <listitem><para>Static, private vendor data that is compatible
 551         with all architectures.</para></listitem>
 552       </varlistentry>
 553
 554       <varlistentry>
 555         <term><filename>~/.local/lib/<replaceable>arch-id</replaceable></filename></term>
 556
 557         <listitem><para>Location for placing public dynamic libraries.
 558         The architecture identifier to use is defined on <ulink
 559         url="https://wiki.debian.org/Multiarch/Tuples">Multiarch
 560         Architecture Specifiers (Tuples)</ulink>
 561         list.</para></listitem>
 562       </varlistentry>
 563
 564       <varlistentry>
 565         <term><filename>~/.local/share</filename></term>
 566
 567         <listitem><para>Resources shared between multiple packages,
 568         such as fonts or artwork. Usually, the precise location and
 569         format of files stored below this directory is subject to
 570         specifications that ensure interoperability. If an application
 571         finds <varname>$XDG_DATA_HOME</varname> set, it should use the
 572         directory specified in it instead of this
 573         directory.</para></listitem>
 574       </varlistentry>
 575
 576     </variablelist>
 577   </refsect1>
 578
 579
 580   <refsect1>
 581     <title>Unprivileged Write Access</title>
 582
 583     <para>Unprivileged processes generally lack write access to most
 584     of the hierarchy.</para>
 585
 586     <para>The exceptions for normal users are
 587     <filename>/tmp</filename>,
 588     <filename>/var/tmp</filename>,
 589     <filename>/dev/shm</filename>, as well as the home directory
 590     <varname>$HOME</varname> (usually found below
 591     <filename>/home</filename>) and the runtime directory
 592     <varname>$XDG_RUNTIME_DIR</varname> (found below
 593     <filename>/run/user</filename>) of the user, which are all
 594     writable.</para>
 595
 596     <para>For unprivileged system processes, only
 597     <filename>/tmp</filename>,
 598     <filename>/var/tmp</filename> and
 599     <filename>/dev/shm</filename> are writable. If an
 600     unprivileged system process needs a private writable directory in
 601     <filename>/var</filename> or <filename>/run</filename>, it is
 602     recommended to either create it before dropping privileges in the
 603     daemon code, to create it via
 604     <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 605     fragments during boot, or via the
 606     <varname>RuntimeDirectory=</varname> directive of service units
 607     (see
 608     <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 609     for details).</para>
 610   </refsect1>
 611
 612   <refsect1>
 613     <title>Node Types</title>
 614
 615     <para>Unix file systems support different types of file nodes,
 616     including regular files, directories, symlinks, character and
 617     block device nodes, sockets and FIFOs.</para>
 618
 619     <para>It is strongly recommended that <filename>/dev</filename> is
 620     the only location below which device nodes shall be placed.
 621     Similarly, <filename>/run</filename> shall be the only location to
 622     place sockets and FIFOs. Regular files, directories and symlinks
 623     may be used in all directories.</para>
 624   </refsect1>
 625
 626   <refsect1>
 627     <title>System Packages</title>
 628
 629     <para>Developers of system packages should follow strict rules
 630     when placing their own files in the file system. The following
 631     table lists recommended locations for specific types of files
 632     supplied by the vendor.</para>
 633
 634     <table>
 635       <title>System Package Vendor Files Locations</title>
 636       <tgroup cols='2' align='left' colsep='1' rowsep='1'>
 637         <colspec colname="directory" />
 638         <colspec colname="purpose" />
 639         <thead>
 640           <row>
 641       <entry>Directory</entry>
 642       <entry>Purpose</entry>
 643           </row>
 644         </thead>
 645         <tbody>
 646           <row>
 647       <entry><filename>/usr/bin</filename></entry>
 648       <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>
 649           </row>
 650           <row>
 651       <entry><filename>/usr/lib/<replaceable>arch-id</replaceable></filename></entry>
 652       <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>
 653           </row>
 654           <row>
 655       <entry><filename>/usr/lib/<replaceable>package</replaceable></filename></entry>
 656       <entry>Private static vendor resources of the package, including private binaries and libraries, or any other kind of read-only vendor data.</entry>
 657           </row>
 658           <row>
 659       <entry><filename>/usr/lib/<replaceable>arch-id</replaceable>/<replaceable>package</replaceable></filename></entry>
 660       <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>
 661           </row>
 662           <row>
 663       <entry><filename>/usr/include/<replaceable>package</replaceable></filename></entry>
 664       <entry>Public C/C++ APIs of public shared libraries of the package.</entry>
 665           </row>
 666         </tbody>
 667       </tgroup>
 668     </table>
 669
 670     <para>Additional static vendor files may be installed in the
 671     <filename>/usr/share</filename> hierarchy to the locations
 672     defined by the various relevant specifications.</para>
 673
 674     <para>During runtime, and for local configuration and state,
 675     additional directories are defined:</para>
 676
 677     <table>
 678       <title>System Package Variable Files Locations</title>
 679       <tgroup cols='2' align='left' colsep='1' rowsep='1'>
 680         <colspec colname="directory" />
 681         <colspec colname="purpose" />
 682         <thead>
 683           <row>
 684       <entry>Directory</entry>
 685       <entry>Purpose</entry>
 686           </row>
 687         </thead>
 688         <tbody>
 689           <row>
 690       <entry><filename>/etc/<replaceable>package</replaceable></filename></entry>
 691       <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>
 692           </row>
 693           <row>
 694       <entry><filename>/run/<replaceable>package</replaceable></filename></entry>
 695       <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>
 696           </row>
 697           <row>
 698       <entry><filename>/run/log/<replaceable>package</replaceable></filename></entry>
 699       <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>
 700           </row>
 701           <row>
 702       <entry><filename>/var/cache/<replaceable>package</replaceable></filename></entry>
 703       <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>
 704           </row>
 705           <row>
 706       <entry><filename>/var/lib/<replaceable>package</replaceable></filename></entry>
 707       <entry>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 <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry> fragment may be used to create the necessary directories during boot.</entry>
 708           </row>
 709           <row>
 710       <entry><filename>/var/log/<replaceable>package</replaceable></filename></entry>
 711       <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>
 712           </row>
 713           <row>
 714       <entry><filename>/var/spool/<replaceable>package</replaceable></filename></entry>
 715       <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>
 716           </row>
 717         </tbody>
 718       </tgroup>
 719     </table>
 720   </refsect1>
 721
 722   <refsect1>
 723     <title>User Packages</title>
 724
 725     <para>Programs running in user context should follow strict rules
 726     when placing their own files in the user's home directory. The
 727     following table lists recommended locations in the home directory
 728     for specific types of files supplied by the vendor if the
 729     application is installed in the home directory. (Note, however,
 730     that user applications installed system-wide should follow the
 731     rules outlined above regarding placing vendor files.)</para>
 732
 733     <table>
 734       <title>User Package Vendor File Locations</title>
 735       <tgroup cols='2' align='left' colsep='1' rowsep='1'>
 736         <colspec colname="directory" />
 737         <colspec colname="purpose" />
 738         <thead>
 739           <row>
 740       <entry>Directory</entry>
 741       <entry>Purpose</entry>
 742           </row>
 743         </thead>
 744         <tbody>
 745           <row>
 746       <entry><filename>~/.local/bin</filename></entry>
 747       <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>
 748           </row>
 749           <row>
 750       <entry><filename>~/.local/lib/<replaceable>arch-id</replaceable></filename></entry>
 751       <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>
 752           </row>
 753           <row>
 754       <entry><filename>~/.local/lib/<replaceable>package</replaceable></filename></entry>
 755       <entry>Private, static vendor resources of the package, compatible with any architecture, or any other kind of read-only vendor data.</entry>
 756           </row>
 757           <row>
 758       <entry><filename>~/.local/lib/<replaceable>arch-id</replaceable>/<replaceable>package</replaceable></filename></entry>
 759       <entry>Private other vendor resources of the package that are architecture-specific and cannot be shared between architectures.</entry>
 760           </row>
 761         </tbody>
 762       </tgroup>
 763     </table>
 764
 765     <para>Additional static vendor files may be installed in the
 766     <filename>~/.local/share</filename> hierarchy to the locations
 767     defined by the various relevant specifications.</para>
 768
 769     <para>During runtime, and for local configuration and state,
 770     additional directories are defined:</para>
 771
 772     <table>
 773       <title>User Package Variable File Locations</title>
 774       <tgroup cols='2' align='left' colsep='1' rowsep='1'>
 775         <colspec colname="directory" />
 776         <colspec colname="purpose" />
 777         <thead>
 778           <row>
 779       <entry>Directory</entry>
 780       <entry>Purpose</entry>
 781           </row>
 782         </thead>
 783         <tbody>
 784           <row>
 785       <entry><filename>~/.config/<replaceable>package</replaceable></filename></entry>
 786       <entry>User-specific configuration and state for the package. It is required to default to safe fallbacks if this configuration is missing.</entry>
 787           </row>
 788           <row>
 789       <entry><filename><varname>$XDG_RUNTIME_DIR</varname>/<replaceable>package</replaceable></filename></entry>
 790       <entry>User runtime data for the package.</entry>
 791           </row>
 792           <row>
 793       <entry><filename>~/.cache/<replaceable>package</replaceable></filename></entry>
 794       <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>
 795           </row>
 796         </tbody>
 797       </tgroup>
 798     </table>
 799   </refsect1>
 800
 801   <refsect1>
 802     <title>See Also</title>
 803     <para>
 804       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 805       <citerefentry project='man-pages'><refentrytitle>hier</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 806       <citerefentry><refentrytitle>systemd-path</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 807       <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 808       <citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 809       <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 810       <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 811       <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 812     </para>
 813   </refsect1>
 814
 815 </refentry>