man7/hier.7

   1 .\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
   2 .\"
   3 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   4 .\"
   5 .\" Modified Sun Jul 25 11:05:58 1993 by Rik Faith (faith@cs.unc.edu)
   6 .\" Modified Sat Feb 10 16:18:03 1996 by Urs Thuermann (urs@isnogud.escape.de)
   7 .\" Modified Mon Jun 16 20:02:00 1997 by Nicolás Lichtmaier <nick@debian.org>
   8 .\" Modified Mon Feb  6 16:41:00 1999 by Nicolás Lichtmaier <nick@debian.org>
   9 .\" Modified Tue Feb  8 16:46:45 2000 by Chris Pepper <pepper@tgg.com>
  10 .\" Modified Fri Sep  7 20:32:45 2001 by Tammy Fox <tfox@redhat.com>
  11 .TH HIER 7 2021-03-22 "Linux" "Linux Programmer's Manual"
  12 .SH NAME
  13 hier \- description of the filesystem hierarchy
  14 .SH DESCRIPTION
  15 A typical Linux system has, among others, the following directories:
  16 .TP
  17 .I /
  18 This is the root directory.
  19 This is where the whole tree starts.
  20 .TP
  21 .I /bin
  22 This directory contains executable programs which are needed in
  23 single user mode and to bring the system up or repair it.
  24 .TP
  25 .I /boot
  26 Contains static files for the boot loader.
  27 This directory holds only
  28 the files which are needed during the boot process.
  29 The map installer
  30 and configuration files should go to
  31 .I /sbin
  32 and
  33 .IR /etc .
  34 The operating system kernel (initrd for example) must be located in either
  35 .I /
  36 or
  37 .IR /boot .
  38 .TP
  39 .I /dev
  40 Special or device files, which refer to physical devices.
  41 See
  42 .BR mknod (1).
  43 .TP
  44 .I /etc
  45 Contains configuration files which are local to the machine.
  46 Some
  47 larger software packages, like X11, can have their own subdirectories
  48 below
  49 .IR /etc .
  50 Site-wide configuration files may be placed here or in
  51 .IR /usr/etc .
  52 Nevertheless, programs should always look for these files in
  53 .I /etc
  54 and you may have links for these files to
  55 .IR /usr/etc .
  56 .TP
  57 .I /etc/opt
  58 Host-specific configuration files for add-on applications installed
  59 in
  60 .IR /opt .
  61 .TP
  62 .I /etc/sgml
  63 This directory contains the configuration files for SGML (optional).
  64 .TP
  65 .I /etc/skel
  66 When a new user account is created, files from this directory are
  67 usually copied into the user's home directory.
  68 .TP
  69 .I /etc/X11
  70 Configuration files for the X11 window system (optional).
  71 .TP
  72 .I /etc/xml
  73 This directory contains the configuration files for XML (optional).
  74 .TP
  75 .I /home
  76 On machines with home directories for users, these are usually beneath
  77 this directory, directly or not.
  78 The structure of this directory
  79 depends on local administration decisions (optional).
  80 .TP
  81 .I /lib
  82 This directory should hold those shared libraries that are necessary
  83 to boot the system and to run the commands in the root filesystem.
  84 .TP
  85 .I /lib<qual>
  86 These directories are variants of
  87 .I /lib
  88 on system which support more than one binary format requiring separate
  89 libraries (optional).
  90 .TP
  91 .I /lib/modules
  92 Loadable kernel modules (optional).
  93 .TP
  94 .I /lost+found
  95 This directory contains items lost in the filesystem.
  96 These items are usually chunks of files mangled as a consequence of
  97 a faulty disk or a system crash.
  98 .TP
  99 .I /media
 100 This directory contains mount points for removable media such as CD
 101 and DVD disks or USB sticks.
 102 On systems where more than one device exists
 103 for mounting a certain type of media,
 104 mount directories can be created by appending a digit
 105 to the name of those available above starting with '0',
 106 but the unqualified name must also exist.
 107 .TP
 108 .I /media/floppy[1\-9]
 109 Floppy drive (optional).
 110 .TP
 111 .I /media/cdrom[1\-9]
 112 CD-ROM drive (optional).
 113 .TP
 114 .I /media/cdrecorder[1\-9]
 115 CD writer (optional).
 116 .TP
 117 .I /media/zip[1\-9]
 118 Zip drive (optional).
 119 .TP
 120 .I /media/usb[1\-9]
 121 USB drive (optional).
 122 .TP
 123 .I /mnt
 124 This directory is a mount point for a temporarily mounted filesystem.
 125 In some distributions,
 126 .I /mnt
 127 contains subdirectories intended to be used as mount points for several
 128 temporary filesystems.
 129 .TP
 130 .I /opt
 131 This directory should contain add-on packages that contain static files.
 132 .TP
 133 .I /proc
 134 This is a mount point for the
 135 .I proc
 136 filesystem, which provides information about running processes and
 137 the kernel.
 138 This pseudo-filesystem is described in more detail in
 139 .BR proc (5).
 140 .TP
 141 .I /root
 142 This directory is usually the home directory for the root user (optional).
 143 .TP
 144 .I /run
 145 This directory contains information which describes the system since it was booted.
 146 Once this purpose was served by
 147 .IR /var/run
 148 and programs may continue to use it.
 149 .TP
 150 .I /sbin
 151 Like
 152 .IR /bin ,
 153 this directory holds commands needed to boot the system, but which are
 154 usually not executed by normal users.
 155 .TP
 156 .I /srv
 157 This directory contains site-specific data that is served by this system.
 158 .TP
 159 .I /sys
 160 This is a mount point for the sysfs filesystem, which provides information
 161 about the kernel like
 162 .IR /proc ,
 163 but better structured, following the formalism of kobject infrastructure.
 164 .TP
 165 .I /tmp
 166 This directory contains temporary files which may be deleted with no
 167 notice, such as by a regular job or at system boot up.
 168 .TP
 169 .I /usr
 170 This directory is usually mounted from a separate partition.
 171 It should hold only shareable, read-only data, so that it can be mounted
 172 by various machines running Linux.
 173 .TP
 174 .I /usr/X11R6
 175 The X\-Window system, version 11 release 6 (present in FHS 2.3, removed
 176 in FHS 3.0).
 177 .TP
 178 .I /usr/X11R6/bin
 179 Binaries which belong to the X\-Window system; often, there is a
 180 symbolic link from the more traditional
 181 .I /usr/bin/X11
 182 to here.
 183 .TP
 184 .I /usr/X11R6/lib
 185 Data files associated with the X\-Window system.
 186 .TP
 187 .I /usr/X11R6/lib/X11
 188 These contain miscellaneous files needed to run X;  Often, there is a
 189 symbolic link from
 190 .I /usr/lib/X11
 191 to this directory.
 192 .TP
 193 .I /usr/X11R6/include/X11
 194 Contains include files needed for compiling programs using the X11
 195 window system.
 196 Often, there is a symbolic link from
 197 .I /usr/include/X11
 198 to this directory.
 199 .TP
 200 .I /usr/bin
 201 This is the primary directory for executable programs.
 202 Most programs
 203 executed by normal users which are not needed for booting or for
 204 repairing the system and which are not installed locally should be
 205 placed in this directory.
 206 .TP
 207 .I /usr/bin/mh
 208 Commands for the MH mail handling system (optional).
 209 .TP
 210 .I /usr/bin/X11
 211 This is the traditional place to look for X11 executables; on Linux, it
 212 usually is a symbolic link to
 213 .IR /usr/X11R6/bin .
 214 .TP
 215 .I /usr/dict
 216 Replaced by
 217 .IR /usr/share/dict .
 218 .TP
 219 .I /usr/doc
 220 Replaced by
 221 .IR /usr/share/doc .
 222 .TP
 223 .I /usr/etc
 224 Site-wide configuration files to be shared between several machines
 225 may be stored in this directory.
 226 However, commands should always
 227 reference those files using the
 228 .I /etc
 229 directory.
 230 Links from files in
 231 .I /etc
 232 should point to the appropriate files in
 233 .IR /usr/etc .
 234 .TP
 235 .I /usr/games
 236 Binaries for games and educational programs (optional).
 237 .TP
 238 .I /usr/include
 239 Include files for the C compiler.
 240 .TP
 241 .I /usr/include/bsd
 242 BSD compatibility include files (optional).
 243 .TP
 244 .I /usr/include/X11
 245 Include files for the C compiler and the X\-Window system.
 246 This is
 247 usually a symbolic link to
 248 .IR /usr/X11R6/include/X11 .
 249 .TP
 250 .I /usr/include/asm
 251 Include files which declare some assembler functions.
 252 This used to be a
 253 symbolic link to
 254 .IR /usr/src/linux/include/asm .
 255 .TP
 256 .I /usr/include/linux
 257 This contains information which may change from system release to
 258 system release and used to be a symbolic link to
 259 .I /usr/src/linux/include/linux
 260 to get at operating-system-specific information.
 261 .IP
 262 (Note that one should have include files there that work correctly with
 263 the current libc and in user space.
 264 However, Linux kernel source is not
 265 designed to be used with user programs and does not know anything
 266 about the libc you are using.
 267 It is very likely that things will break
 268 if you let
 269 .I /usr/include/asm
 270 and
 271 .I /usr/include/linux
 272 point at a random kernel tree.
 273 Debian systems don't do this
 274 and use headers from a known good kernel
 275 version, provided in the libc*-dev package.)
 276 .TP
 277 .I /usr/include/g++
 278 Include files to use with the GNU C++ compiler.
 279 .TP
 280 .I /usr/lib
 281 Object libraries, including dynamic libraries, plus some executables
 282 which usually are not invoked directly.
 283 More complicated programs may
 284 have whole subdirectories there.
 285 .TP
 286 .I /usr/libexec
 287 Directory contains binaries for internal use only and they are not meant
 288 to be executed directly by users shell or scripts.
 289 .TP
 290 .I /usr/lib<qual>
 291 These directories are variants of
 292 .I /usr/lib
 293 on system which support more than one binary format requiring separate
 294 libraries, except that the symbolic link
 295 .I /usr/lib<qual>/X11
 296 is not required (optional).
 297 .TP
 298 .I /usr/lib/X11
 299 The usual place for data files associated with X programs, and
 300 configuration files for the X system itself.
 301 On Linux, it usually is
 302 a symbolic link to
 303 .IR /usr/X11R6/lib/X11 .
 304 .TP
 305 .I /usr/lib/gcc\-lib
 306 contains executables and include files for the GNU C compiler,
 307 .BR gcc (1).
 308 .TP
 309 .I /usr/lib/groff
 310 Files for the GNU groff document formatting system.
 311 .TP
 312 .I /usr/lib/uucp
 313 Files for
 314 .BR uucp (1).
 315 .TP
 316 .I /usr/local
 317 This is where programs which are local to the site typically go.
 318 .TP
 319 .I /usr/local/bin
 320 Binaries for programs local to the site.
 321 .TP
 322 .I /usr/local/doc
 323 Local documentation.
 324 .TP
 325 .I /usr/local/etc
 326 Configuration files associated with locally installed programs.
 327 .TP
 328 .I /usr/local/games
 329 Binaries for locally installed games.
 330 .TP
 331 .I /usr/local/lib
 332 Files associated with locally installed programs.
 333 .TP
 334 .I /usr/local/lib<qual>
 335 These directories are variants of
 336 .I /usr/local/lib
 337 on system which support more than one binary format requiring separate
 338 libraries (optional).
 339 .TP
 340 .I /usr/local/include
 341 Header files for the local C compiler.
 342 .TP
 343 .I /usr/local/info
 344 Info pages associated with locally installed programs.
 345 .TP
 346 .I /usr/local/man
 347 Man pages associated with locally installed programs.
 348 .TP
 349 .I /usr/local/sbin
 350 Locally installed programs for system administration.
 351 .TP
 352 .I /usr/local/share
 353 Local application data that can be shared among different architectures
 354 of the same OS.
 355 .TP
 356 .I /usr/local/src
 357 Source code for locally installed software.
 358 .TP
 359 .I /usr/man
 360 Replaced by
 361 .IR /usr/share/man .
 362 .TP
 363 .I /usr/sbin
 364 This directory contains program binaries for system administration
 365 which are not essential for the boot process, for mounting
 366 .IR /usr ,
 367 or for system repair.
 368 .TP
 369 .I /usr/share
 370 This directory contains subdirectories with specific application data, that
 371 can be shared among different architectures of the same OS.
 372 Often one finds stuff here that used to live in
 373 .I /usr/doc
 374 or
 375 .I /usr/lib
 376 or
 377 .IR /usr/man .
 378 .TP
 379 .I /usr/share/color
 380 Contains color management information, like International Color Consortium (ICC)
 381 Color profiles (optional).
 382 .TP
 383 .I /usr/share/dict
 384 Contains the word lists used by spell checkers (optional).
 385 .TP
 386 .I /usr/share/dict/words
 387 List of English words (optional).
 388 .TP
 389 .I /usr/share/doc
 390 Documentation about installed programs (optional).
 391 .TP
 392 .I /usr/share/games
 393 Static data files for games in
 394 .I /usr/games
 395 (optional).
 396 .TP
 397 .I /usr/share/info
 398 Info pages go here (optional).
 399 .TP
 400 .I /usr/share/locale
 401 Locale information goes here (optional).
 402 .TP
 403 .I /usr/share/man
 404 Manual pages go here in subdirectories according to the man page sections.
 405 .TP
 406 .I /usr/share/man/<locale>/man[1\-9]
 407 These directories contain manual pages for the
 408 specific locale in source code form.
 409 Systems which use a unique language and code set for all manual pages
 410 may omit the <locale> substring.
 411 .TP
 412 .I /usr/share/misc
 413 Miscellaneous data that can be shared among different architectures of the
 414 same OS.
 415 .TP
 416 .I /usr/share/nls
 417 The message catalogs for native language support go here (optional).
 418 .TP
 419 .I /usr/share/ppd
 420 Postscript Printer Definition (PPD) files (optional).
 421 .TP
 422 .I /usr/share/sgml
 423 Files for SGML (optional).
 424 .TP
 425 .I /usr/share/sgml/docbook
 426 DocBook DTD (optional).
 427 .TP
 428 .I /usr/share/sgml/tei
 429 TEI DTD (optional).
 430 .TP
 431 .I /usr/share/sgml/html
 432 HTML DTD (optional).
 433 .TP
 434 .I /usr/share/sgml/mathtml
 435 MathML DTD (optional).
 436 .TP
 437 .I /usr/share/terminfo
 438 The database for terminfo (optional).
 439 .TP
 440 .I /usr/share/tmac
 441 Troff macros that are not distributed with groff (optional).
 442 .TP
 443 .I /usr/share/xml
 444 Files for XML (optional).
 445 .TP
 446 .I /usr/share/xml/docbook
 447 DocBook DTD (optional).
 448 .TP
 449 .I /usr/share/xml/xhtml
 450 XHTML DTD (optional).
 451 .TP
 452 .I /usr/share/xml/mathml
 453 MathML DTD (optional).
 454 .TP
 455 .I /usr/share/zoneinfo
 456 Files for timezone information (optional).
 457 .TP
 458 .I /usr/src
 459 Source files for different parts of the system, included with some packages
 460 for reference purposes.
 461 Don't work here with your own projects, as files
 462 below /usr should be read-only except when installing software (optional).
 463 .TP
 464 .I /usr/src/linux
 465 This was the traditional place for the kernel source.
 466 Some distributions put here the source for the default kernel they ship.
 467 You should probably use another directory when building your own kernel.
 468 .TP
 469 .I /usr/tmp
 470 Obsolete.
 471 This should be a link
 472 to
 473 .IR /var/tmp .
 474 This link is present only for compatibility reasons and shouldn't be used.
 475 .TP
 476 .I /var
 477 This directory contains files which may change in size, such as spool
 478 and log files.
 479 .TP
 480 .I /var/account
 481 Process accounting logs (optional).
 482 .TP
 483 .I /var/adm
 484 This directory is superseded by
 485 .I /var/log
 486 and should be a symbolic link to
 487 .IR /var/log .
 488 .TP
 489 .I /var/backups
 490 Reserved for historical reasons.
 491 .TP
 492 .I /var/cache
 493 Data cached for programs.
 494 .TP
 495 .I /var/cache/fonts
 496 Locally generated fonts (optional).
 497 .TP
 498 .I /var/cache/man
 499 Locally formatted man pages (optional).
 500 .TP
 501 .I /var/cache/www
 502 WWW proxy or cache data (optional).
 503 .TP
 504 .I /var/cache/<package>
 505 Package specific cache data (optional).
 506 .TP
 507 .IR /var/catman/cat[1\-9] " or " /var/cache/man/cat[1\-9]
 508 These directories contain preformatted manual pages according to their
 509 man page section.
 510 (The use of preformatted manual pages is deprecated.)
 511 .TP
 512 .I /var/crash
 513 System crash dumps (optional).
 514 .TP
 515 .I /var/cron
 516 Reserved for historical reasons.
 517 .TP
 518 .I /var/games
 519 Variable game data (optional).
 520 .TP
 521 .I /var/lib
 522 Variable state information for programs.
 523 .TP
 524 .I /var/lib/color
 525 Variable files containing color management information (optional).
 526 .TP
 527 .I /var/lib/hwclock
 528 State directory for hwclock (optional).
 529 .TP
 530 .I /var/lib/misc
 531 Miscellaneous state data.
 532 .TP
 533 .I /var/lib/xdm
 534 X display manager variable data (optional).
 535 .TP
 536 .I /var/lib/<editor>
 537 Editor backup files and state (optional).
 538 .TP
 539 .I /var/lib/<name>
 540 These directories must be used for all distribution packaging support.
 541 .TP
 542 .I /var/lib/<package>
 543 State data for packages and subsystems (optional).
 544 .TP
 545 .I /var/lib/<pkgtool>
 546 Packaging support files (optional).
 547 .TP
 548 .I /var/local
 549 Variable data for
 550 .IR /usr/local .
 551 .TP
 552 .I /var/lock
 553 Lock files are placed in this directory.
 554 The naming convention for
 555 device lock files is
 556 .I LCK..<device>
 557 where
 558 .I <device>
 559 is the device's name in the filesystem.
 560 The format used is that of HDU UUCP lock files, that is, lock files
 561 contain a PID as a 10-byte ASCII decimal number, followed by a newline
 562 character.
 563 .TP
 564 .I /var/log
 565 Miscellaneous log files.
 566 .TP
 567 .I /var/opt
 568 Variable data for
 569 .IR /opt .
 570 .TP
 571 .I /var/mail
 572 Users' mailboxes.
 573 Replaces
 574 .IR /var/spool/mail .
 575 .TP
 576 .I /var/msgs
 577 Reserved for historical reasons.
 578 .TP
 579 .I /var/preserve
 580 Reserved for historical reasons.
 581 .TP
 582 .I /var/run
 583 Run-time variable files, like files holding process identifiers (PIDs)
 584 and logged user information
 585 .IR (utmp) .
 586 Files in this directory are usually cleared when the system boots.
 587 .TP
 588 .I /var/spool
 589 Spooled (or queued) files for various programs.
 590 .TP
 591 .I /var/spool/at
 592 Spooled jobs for
 593 .BR at (1).
 594 .TP
 595 .I /var/spool/cron
 596 Spooled jobs for
 597 .BR cron (8).
 598 .TP
 599 .I /var/spool/lpd
 600 Spooled files for printing (optional).
 601 .TP
 602 .I /var/spool/lpd/printer
 603 Spools for a specific printer (optional).
 604 .TP
 605 .I /var/spool/mail
 606 Replaced by
 607 .IR /var/mail .
 608 .TP
 609 .I /var/spool/mqueue
 610 Queued outgoing mail (optional).
 611 .TP
 612 .I /var/spool/news
 613 Spool directory for news (optional).
 614 .TP
 615 .I /var/spool/rwho
 616 Spooled files for
 617 .BR rwhod (8)
 618 (optional).
 619 .TP
 620 .I /var/spool/smail
 621 Spooled files for the
 622 .BR smail (1)
 623 mail delivery program.
 624 .TP
 625 .I /var/spool/uucp
 626 Spooled files for
 627 .BR uucp (1)
 628 (optional).
 629 .TP
 630 .I /var/tmp
 631 Like
 632 .IR /tmp ,
 633 this directory holds temporary files stored for an unspecified duration.
 634 .TP
 635 .I /var/yp
 636 Database files for NIS,
 637 formerly known as the Sun Yellow Pages (YP).
 638 .SH CONFORMING TO
 639 The Filesystem Hierarchy Standard (FHS), Version 3.0, published March 19, 2015
 640 .UR https://refspecs.linuxfoundation.org/fhs.shtml
 641 .UE .
 642 .SH BUGS
 643 This list is not exhaustive; different distributions and systems may be configured
 644 differently.
 645 .SH SEE ALSO
 646 .BR find (1),
 647 .BR ln (1),
 648 .BR proc (5),
 649 .BR file\-hierarchy (7),
 650 .BR mount (8)
 651 .PP
 652 The Filesystem Hierarchy Standard