man/file-hierarchy.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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   8   Copyright 2014 Lennart Poettering
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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
  56                 file system hierarchy inspired by UNIX, more
  57                 specificaly the hierarchy 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><refentrytitle>hier</refentrytitle><manvolnum>7</manvolnum></citerefentry>. This
  61                 manual page describes a more minimal, modernized
  62                 subset of these specifications that defines more
  63                 strictly the suggestions and restrictions systemd
  64                 makes on the file system hierarchy.</para>
  65         </refsect1>
  66
  67         <refsect1>
  68                 <title>General Structure</title>
  69
  70                 <variablelist>
  71                         <varlistentry>
  72                                 <term><filename>/</filename></term>
  73                                 <listitem><para>The file system
  74                                 root. Usually writable, but this is
  75                                 not required. Possibly a temporary
  76                                 file system (<literal>tmpfs</literal>). Not shared with
  77                                 other hosts (unless read-only). The
  78                                 administrator may create additional
  79                                 top-level subdirectories in this tree,
  80                                 if required and the name does not
  81                                 conflict with any of the directories
  82                                 listed below.</para></listitem>
  83                         </varlistentry>
  84
  85                         <varlistentry>
  86                                 <term><filename>/boot</filename></term>
  87                                 <listitem><para>The boot partition
  88                                 used for bringing up the system. On
  89                                 EFI systems this is possibly the EFI
  90                                 System Partition, also see
  91                                 <citerefentry><refentrytitle>systemd-boot-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>. This
  92                                 directory is usually strictly local
  93                                 the host, and should be considered
  94                                 read-only, except when a new kernel or
  95                                 boot loader is installed. This
  96                                 directory only exists on systems that
  97                                 run on physical or emulated hardware
  98                                 that requires boot
  99                                 loaders.</para></listitem>
 100                         </varlistentry>
 101
 102                         <varlistentry>
 103                                 <term><filename>/etc</filename></term>
 104                                 <listitem><para>System-specific
 105                                 configuration. This directory may or
 106                                 may not be read-only. Frequently, this
 107                                 directory is pre-populated with
 108                                 vendor-supplied configuration files,
 109                                 but applications should not make
 110                                 assumptions about this directory
 111                                 being fully populated or populated at
 112                                 all, and should fall back to defaults
 113                                 if configuration is missing.</para></listitem>
 114                         </varlistentry>
 115
 116                         <varlistentry>
 117                                 <term><filename>/home</filename></term>
 118                                 <listitem><para>The location for
 119                                 normal user's home
 120                                 directories. Possibly shared with
 121                                 other systems, and never
 122                                 read-only. This directory should only
 123                                 be used for normal users, never for
 124                                 system users. This directory and
 125                                 possibly the directories contained
 126                                 within it might only become available
 127                                 or writable in late boot or even on
 128                                 user login only. This directory might
 129                                 be placed on limited-functionality
 130                                 network file systems, hence
 131                                 applications should not assume the
 132                                 full set of file API is available on
 133                                 this directory.</para></listitem>
 134                         </varlistentry>
 135
 136                         <varlistentry>
 137                                 <term><filename>/root</filename></term>
 138                                 <listitem><para>The home directory of
 139                                 the root user. The root user's home
 140                                 directory is located outside of
 141                                 <filename>/home</filename> in order to
 142                                 make sure the root user may log in
 143                                 even without <filename>/home</filename>
 144                                 being available and
 145                                 mounted.</para></listitem>
 146                         </varlistentry>
 147
 148                         <varlistentry>
 149                                 <term><filename>/srv</filename></term>
 150                                 <listitem><para>The place to store
 151                                 general server payload, managed by the
 152                                 administrator. No restrictions are
 153                                 made how this directory is organized
 154                                 internally. Generally writable, and
 155                                 possibly shared among systems. This
 156                                 directory might become available or
 157                                 writable only very late during
 158                                 boot.</para></listitem>
 159                         </varlistentry>
 160
 161                         <varlistentry>
 162                                 <term><filename>/tmp</filename></term>
 163                                 <listitem><para>The place for small
 164                                 temporary files. This directory is
 165                                 usually mounted as
 166                                 <literal>tmpfs</literal> instance, and
 167                                 should hence not be used for larger
 168                                 files. Since the directory is
 169                                 accessible to other users of the
 170                                 system it is essential that this
 171                                 directory is only written to with the
 172                                 <citerefentry><refentrytitle>mkstemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 173                                 <citerefentry><refentrytitle>mkdtemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 174                                 and related calls. This directory is
 175                                 usually flushed at boot-up. Also,
 176                                 files that are not accessed within a
 177                                 certain time are usually automatically
 178                                 deleted.</para></listitem>
 179                         </varlistentry>
 180
 181                 </variablelist>
 182         </refsect1>
 183
 184         <refsect1>
 185                 <title>Runtime Data</title>
 186
 187                 <variablelist>
 188                         <varlistentry>
 189                                 <term><filename>/run</filename></term>
 190                                 <listitem><para>A
 191                                 <literal>tmpfs</literal> file system
 192                                 for system packages to place runtime
 193                                 data in. This directory is flushed on
 194                                 boot, and generally writable for
 195                                 priviliged programs
 196                                 only. Always writable.</para></listitem>
 197                         </varlistentry>
 198
 199                         <varlistentry>
 200                                 <term><filename>/run/log</filename></term>
 201                                 <listitem><para>Runtime system
 202                                 logs. System components may place
 203                                 private logs in this directory. Always
 204                                 writable, even when
 205                                 <filename>/var/log</filename> might
 206                                 not be accessible
 207                                 yet.</para></listitem>
 208                         </varlistentry>
 209
 210                         <varlistentry>
 211                                 <term><filename>/run/user</filename></term>
 212                                 <listitem><para>Contains per-user
 213                                 runtime directories, each usually
 214                                 invidually mounted
 215                                 <literal>tmpfs</literal>
 216                                 instances. Always writable, flushed at
 217                                 each reboot and when the user logs
 218                                 out. User code should not reference
 219                                 this directory directly, but via the
 220                                 <varname>$XDG_RUNTIME_DIR</varname>
 221                                 environment variable, as documented in
 222                                 the <ulink
 223                                 url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
 224                                 Base Directory
 225                                 Specification</ulink>.</para></listitem>
 226                         </varlistentry>
 227                 </variablelist>
 228         </refsect1>
 229
 230         <refsect1>
 231                 <title>Vendor-supplied Operating System Resources</title>
 232
 233                 <variablelist>
 234
 235                         <varlistentry>
 236                                 <term><filename>/usr</filename></term>
 237                                 <listitem><para>Vendor-supplied
 238                                 operating system resources. Usually
 239                                 read-only, but this is not
 240                                 required. Possibly shared between
 241                                 multiple hosts. This directory should
 242                                 not be modified by the administrator,
 243                                 except when installing or removing
 244                                 vendor-supplied
 245                                 packages.</para></listitem>
 246                         </varlistentry>
 247
 248                         <varlistentry>
 249                                 <term><filename>/usr/bin</filename></term>
 250                                 <listitem><para>Binaries for user
 251                                 commands, that shall appear in the
 252                                 <varname>$PATH</varname> search
 253                                 path. It is recommended not to place
 254                                 binaries in this directory that are
 255                                 not useful for invocation from a shell
 256                                 (such as daemon binaries); these
 257                                 should be placed in a subdirectory of
 258                                 <filename>/usr/lib</filename>
 259                                 instead.</para></listitem>
 260                         </varlistentry>
 261
 262                         <varlistentry>
 263                                 <term><filename>/usr/include</filename></term>
 264                                 <listitem><para>C and C++ API header
 265                                 files of system
 266                                 libraries.</para></listitem>
 267                         </varlistentry>
 268
 269                         <varlistentry>
 270                                 <term><filename>/usr/lib</filename></term>
 271                                 <listitem><para>System libraries and
 272                                 package-specific
 273                                 data.</para></listitem>
 274                         </varlistentry>
 275
 276                         <varlistentry>
 277                                 <term><filename>/usr/lib64</filename></term>
 278                                 <listitem><para>Secondary library
 279                                 directory for placing 64bit versions
 280                                 of system libraries in, if the primary
 281                                 architecture of the system is
 282                                 32bit. This directory should not be
 283                                 used for package-specific data, unless
 284                                 this data requires 64bit-specific
 285                                 versions, too.</para></listitem>
 286                         </varlistentry>
 287
 288                         <varlistentry>
 289                                 <term><filename>/usr/share</filename></term>
 290                                 <listitem><para>Resources shared
 291                                 betwen multiple packages, such as
 292                                 documentation, man pages, time zone
 293                                 information, fonts and other
 294                                 resources.</para></listitem>
 295                         </varlistentry>
 296
 297                         <varlistentry>
 298                                 <term><filename>/usr/share/doc</filename></term>
 299                                 <listitem><para>Documentation for the
 300                                 operating system or system
 301                                 packages.</para></listitem>
 302                         </varlistentry>
 303
 304                         <varlistentry>
 305                                 <term><filename>/usr/share/factory/etc</filename></term>
 306                                 <listitem><para>Repository for
 307                                 vendor-supplied default configuration
 308                                 files. This directory should be
 309                                 populated with pristine vendor versions
 310                                 of all configuration files that may be
 311                                 placed in
 312                                 <filename>/etc</filename>. This is
 313                                 useful to compare the local
 314                                 configuration of a system with vendor
 315                                 defaults and to populate the local
 316                                 configuration with
 317                                 defaults.</para></listitem>
 318                         </varlistentry>
 319
 320                         <varlistentry>
 321                                 <term><filename>/usr/share/factory/var</filename></term>
 322
 323                                 <listitem><para>Similar to
 324                                 <filename>/usr/share/factory/etc</filename>
 325                                 but for vendor versions of files in
 326                                 the variable, persistent data
 327                                 directory
 328                                 <filename>/var</filename>.</para></listitem>
 329
 330                         </varlistentry>
 331                 </variablelist>
 332         </refsect1>
 333
 334         <refsect1>
 335                 <title>Persistent Variable System Data</title>
 336
 337                 <variablelist>
 338                         <varlistentry>
 339                                 <term><filename>/var</filename></term>
 340                                 <listitem><para>Persistent, variable
 341                                 system data. Must be writable. This
 342                                 directory might be pre-populated with
 343                                 vendor-supplied data, but applications
 344                                 should be able to reconstruct
 345                                 necessary files and directories in
 346                                 this subhierarchy should they be
 347                                 missing, as the system might start up
 348                                 without this directory being
 349                                 populated. Persistency is recommended,
 350                                 but optional, to support ephemeral
 351                                 systems. This directory might become
 352                                 available or writable only very late
 353                                 during boot. Components that are
 354                                 required to operate during early boot
 355                                 hence shall not unconditionally rely
 356                                 on this directory.</para></listitem>
 357                         </varlistentry>
 358
 359                         <varlistentry>
 360                                 <term><filename>/var/cache</filename></term>
 361                                 <listitem><para>Persistent system
 362                                 cache data. System components may
 363                                 place non-essential data in this
 364                                 directory. Flushing this directory
 365                                 should have no effect on operation of
 366                                 programs, except for increased
 367                                 runtimes necessary to rebuild these
 368                                 caches.</para></listitem>
 369                         </varlistentry>
 370
 371                         <varlistentry>
 372                                 <term><filename>/var/lib</filename></term>
 373                                 <listitem><para>Persistent system
 374                                 data. System components may
 375                                 place private data in this
 376                                 directory.</para></listitem>
 377                         </varlistentry>
 378
 379                         <varlistentry>
 380                                 <term><filename>/var/log</filename></term>
 381                                 <listitem><para>Persistent system
 382                                 logs. System components may place
 383                                 private logs in this directory, though
 384                                 it is recommended to do most logging
 385                                 via the
 386                                 <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 387                                 and
 388                                 <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 389                                 calls.</para></listitem>
 390                         </varlistentry>
 391
 392                         <varlistentry>
 393                                 <term><filename>/var/spool</filename></term>
 394                                 <listitem><para>Persistent system
 395                                 spool data, such as printer or mail
 396                                 queues.</para></listitem>
 397                         </varlistentry>
 398
 399                         <varlistentry>
 400                                 <term><filename>/var/tmp</filename></term>
 401                                 <listitem><para>The place for larger
 402                                 and persistent temporary files. In
 403                                 contrast to <filename>/tmp</filename>
 404                                 this directory is usually mounted from
 405                                 a persistent physical file system and
 406                                 can thus accept larger files. This
 407                                 directory is generally not flushed at
 408                                 boot-up, but time-based cleanup of
 409                                 files that have not been accessed for
 410                                 a certain time is applied. The same
 411                                 security restrictions as with
 412                                 <filename>/tmp</filename> apply, and
 413                                 hence only
 414                                 <citerefentry><refentrytitle>mkstemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 415                                 <citerefentry><refentrytitle>mkdtemp</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 416                                 or similar calls should be used to
 417                                 make use of this directory.
 418                                 </para></listitem>
 419                         </varlistentry>
 420
 421                 </variablelist>
 422         </refsect1>
 423
 424         <refsect1>
 425                 <title>Virtual Kernel and API File Systems</title>
 426
 427                 <variablelist>
 428                         <varlistentry>
 429                                 <term><filename>/dev</filename></term>
 430                                 <listitem><para>The root directory for
 431                                 device nodes. Usually this directory
 432                                 is mounted as
 433                                 <literal>devtmpfs</literal> instance,
 434                                 but might be of a different type in
 435                                 sandboxed/containerized setups. This
 436                                 directory is managed jointly by the
 437                                 kernel and
 438                                 <citerefentry><refentrytitle>systemd-udevd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 439                                 and should not be written to by other
 440                                 components. A number of special
 441                                 purpose virtual file systems might be
 442                                 mounted below this
 443                                 directory.</para></listitem>
 444                         </varlistentry>
 445
 446                         <varlistentry>
 447                                 <term><filename>/dev/shm</filename></term>
 448                                 <listitem><para>Place for POSIX shared
 449                                 memory segments, as created via
 450                                 <citerefentry><refentrytitle>shm_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>. This
 451                                 directory is flushed on boot, and is a
 452                                 <literal>tmpfs</literal> file
 453                                 system. Since all users have write
 454                                 access to this directory, special care
 455                                 should be taken to avoid name clashes
 456                                 and vulnerabilities. For normal users,
 457                                 shared memory segments in this
 458                                 directory are usually deleted when the
 459                                 user logs out. Usually it is a better
 460                                 idea to use memory mapped files in
 461                                 <filename>/run</filename> (for system
 462                                 programs) or
 463                                 <varname>$XDG_RUNTIME_DIR</varname>
 464                                 (for user programs) instead of POSIX
 465                                 shared memory segments, since they
 466                                 directories are not world-writable and
 467                                 hence not vulnerable to
 468                                 security-sensitive name
 469                                 clashes.</para></listitem>
 470                         </varlistentry>
 471
 472                         <varlistentry>
 473                                 <term><filename>/proc</filename></term>
 474                                 <listitem><para>A virtual kernel file
 475                                 system exposing the process list and
 476                                 other functionality. This file system
 477                                 is mostly an API to interface with the
 478                                 kernel and not a place where normal
 479                                 files may be stored. For details, see
 480                                 <citerefentry><refentrytitle>proc</refentrytitle><manvolnum>5</manvolnum></citerefentry>. A
 481                                 number of special purpose virtual file
 482                                 systems might be mounted below this
 483                                 directory.</para></listitem>
 484                         </varlistentry>
 485
 486                         <varlistentry>
 487                                 <term><filename>/proc/sys</filename></term>
 488                                 <listitem><para>A hierarchy below
 489                                 <filename>/proc</filename> that
 490                                 exposes a number of kernel
 491                                 tunables. The primary way to configure
 492                                 the settings in this API file tree is
 493                                 via
 494                                 <citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 495                                 files. In sandboxed/containerized
 496                                 setups this directory is generally
 497                                 mounted read-only.</para></listitem>
 498                         </varlistentry>
 499
 500                         <varlistentry>
 501                                 <term><filename>/sys</filename></term>
 502                                 <listitem><para>A virtual kernel file
 503                                 system exposing discovered devices and
 504                                 other functionality. This file system
 505                                 is mostly an API to interface with the
 506                                 kernel and not a place where normal
 507                                 files may be stored. In
 508                                 sandboxed/containerized setups this
 509                                 directory is generally mounted
 510                                 read-only. A number of special purpose
 511                                 virtual file systems might be mounted
 512                                 below this
 513                                 directory.</para></listitem>
 514                         </varlistentry>
 515
 516
 517                 </variablelist>
 518         </refsect1>
 519
 520         <refsect1>
 521                 <title>Compatibility Symlinks</title>
 522
 523                 <variablelist>
 524                         <varlistentry>
 525                                 <term><filename>/bin</filename></term>
 526                                 <term><filename>/sbin</filename></term>
 527                                 <term><filename>/usr/sbin</filename></term>
 528
 529                                 <listitem><para>These compatibility
 530                                 symlinks point to
 531                                 <filename>/usr/bin</filename>,
 532                                 ensuring that scripts and binaries
 533                                 referencing these legacy paths
 534                                 correctly find their binaries.</para></listitem>
 535                         </varlistentry>
 536
 537                         <varlistentry>
 538                                 <term><filename>/lib</filename></term>
 539
 540                                 <listitem><para>This compatibility
 541                                 symlink points to
 542                                 <filename>/usr/lib</filename>,
 543                                 ensuring that binaries referencing
 544                                 this legacy path correctly find
 545                                 their libraries.</para></listitem>
 546                         </varlistentry>
 547
 548                         <varlistentry>
 549                                 <term><filename>/lib64</filename></term>
 550
 551                                 <listitem><para>This compatibility
 552                                 symlink points to
 553                                 <filename>/usr/lib64</filename>,
 554                                 ensuring that binaries referencing
 555                                 this legacy path correctly find their
 556                                 libraries. This symlink only exists on
 557                                 architectures whose ABI requires a
 558                                 64bit version of the library
 559                                 directory.</para></listitem>
 560                         </varlistentry>
 561
 562                         <varlistentry>
 563                                 <term><filename>/var/run</filename></term>
 564
 565                                 <listitem><para>This compatibility
 566                                 symlink points to
 567                                 <filename>/run</filename>, ensuring
 568                                 that programs referencing this legacy
 569                                 path correctly find their runtime
 570                                 data.</para></listitem>
 571                         </varlistentry>
 572
 573                 </variablelist>
 574         </refsect1>
 575
 576         <refsect1>
 577                 <title>System Packages</title>
 578
 579                 <para>Developers of system packages should follow
 580                 strict rules when placing their own files in the file
 581                 system. The following table lists recommended
 582                 locations for specific types of files.</para>
 583
 584                 <table>
 585                   <title>System Package Data Location</title>
 586                   <tgroup cols='2' align='left' colsep='1' rowsep='1'>
 587                     <colspec colname="directory" />
 588                     <colspec colname="purpose" />
 589                     <thead>
 590                       <row>
 591                         <entry>Directory</entry>
 592                         <entry>Purpose</entry>
 593                       </row>
 594                     </thead>
 595                     <tbody>
 596                       <row>
 597                         <entry><filename>/usr/bin</filename></entry>
 598                         <entry>Package executables that shall appear in the <varname>$PATH</varname> executable search path. 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 take to pick unique names for files placed here, that are unlikely to clash with other package's files.</entry>
 599                       </row>
 600                       <row>
 601                         <entry><filename>/usr/lib</filename></entry>
 602                         <entry>Public shared libraries of the package, compiled for the primary architecture of the operating system. As above, be careful with using too generic names, and pick unique names for your libraries to place here to avoid name clashes.</entry>
 603                       </row>
 604                       <row>
 605                         <entry><filename>/usr/lib/<replaceable>package</replaceable></filename></entry>
 606                         <entry>Private other vendor resources of the package, including private binaries and libraries, but also including any other kind of read-only vendor data.</entry>
 607                       </row>
 608                       <row>
 609                         <entry><filename>/usr/lib64</filename></entry>
 610                         <entry>Public shared libraries of the package, compiled for the secondary, 64bit architecture, if this is part of the Operating System ABI.</entry>
 611                       </row>
 612                       <row>
 613                         <entry><filename>/usr/lib64/<replaceable>package</replaceable></filename></entry>
 614                         <entry>Private other vendor resources of the package that are architecture-specific and cannot be shared between primary and secondary architectures. Note that this generally does not include private binaries since binaries of the primary architecture may generally be invoked from secondary architecture code just fine.</entry>
 615                       </row>
 616                       <row>
 617                         <entry><filename>/usr/include/<replaceable>package</replaceable></filename></entry>
 618                         <entry>Public C/C++ APIs of public shared libraries of the package.</entry>
 619                       </row>
 620                       <row>
 621                         <entry><filename>/etc/<replaceable>package</replaceable></filename></entry>
 622                         <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 directores from <filename>/usr/share/factory</filename> during boot, via the <literal>L</literal> or <literal>C</literal> directives.</entry>
 623                       </row>
 624                       <row>
 625                         <entry><filename>/run/<replaceable>package</replaceable></filename></entry>
 626                         <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>
 627                       </row>
 628                       <row>
 629                         <entry><filename>/run/log/<replaceable>package</replaceable></filename></entry>
 630                         <entry>Runtime log data for the package.</entry>
 631                       </row>
 632                       <row>
 633                         <entry><filename>/var/cache/<replaceable>package</replaceable></filename></entry>
 634                         <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>
 635                       </row>
 636                       <row>
 637                         <entry><filename>/var/lib/<replaceable>package</replaceable></filename></entry>
 638                         <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>
 639                       </row>
 640                       <row>
 641                         <entry><filename>/var/log/<replaceable>package</replaceable></filename></entry>
 642                         <entry>Persistent log data of the package.</entry>
 643                       </row>
 644                       <row>
 645                         <entry><filename>/var/spool/<replaceable>package</replaceable></filename></entry>
 646                         <entry>Persistent spool/queue data of the package.</entry>
 647                       </row>
 648                     </tbody>
 649                   </tgroup>
 650                 </table>
 651         </refsect1>
 652
 653         <refsect1>
 654                 <title>See Also</title>
 655                 <para>
 656                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 657                         <citerefentry><refentrytitle>hier</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 658                         <citerefentry><refentrytitle>systemd-boot-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 659                         <citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 660                 </para>
 661         </refsect1>
 662
 663 </refentry>