FHS

ファイルシステム階層標準（Filesystem Hierarchy Standard）。一般的にLinuxシステムは以下のようなディレクトリ構造になっている。下記はDebian11の「$man hier」の内容。

ディレクトリ	説明
/	This is the root directory. This is where the whole tree starts.
/bin -> usr/bin	This directory contains executable programs which are needed in single user mode and to bring the system up or repair it.
/usr/bin	This is the primary directory for executable programs. Most programs executed by normal users which are not needed for booting or for repairing the system and which are not installed locally should be placed in this directory.
/boot	Contains static files for the boot loader. This directory holds only the files which are needed during the boot process. The map installer and configuration files should go to /sbin and /etc. The operating system kernel (initrd for example) must be located in either / or /boot.
/dev	Special or device files, which refer to physical devices. See mknod(1).

/etc

ディレクトリ	説明
/etc	Contains configuration files which are local to the machine. Some larger software packages, like X11, can have their own subdirectories below /etc.Site-wide configuration files may be placed here or in /usr/etc. Nevertheless, programs should always look for these files in /etc and you may have links for these files to /usr/etc.
/etc/opt	Host-specific configuration files for add-on applications installed in /opt.
/etc/skel	When a new user account is created, files from this directory are usually copied into the user's home directory.
/etc/sgml	This directory contains the configuration files for SGML (optional).
/etc/X11	Configuration files for the X11 window system (optional).
/etc/xml	This directory contains the configuration files for XML (optional).

ディレクトリ	説明
/home	On machines with home directories for users, these are usually beneath this directory, directly or not. The structure of this directory depends on local administration decisions (optional).	{ /lib ディレクトリ 説明 /lib This directory should hold those shared libraries that are necessary to boot the system and to run the commands in the root filesystem. /lib<qual> These directories are variants of /lib on system which support more than one binary format requiring separate libraries (optional). /lib/modules Loadable kernel modules (optional). ディレクトリ 説明 /lost+found This directory contains items lost in the filesystem. These items are usually chunks of files mangled as a consequence of a faulty disk or a system crash. /media ディレクトリ 説明 /media This directory contains mount points for removable media such as CD and DVD disks or USB sticks. On systems where more than one device exists for mounting a certain type of media, mount directories can be created by appending a digit to the name of those available above starting with '0', but the unqualified name must also exist. /media/floppy[1-9] Floppy drive (optional). /media/cdron[1-9] CD-ROM drive (optional). /media/cdrecorder CD writer (optional). /media/zip[1-9] Zip drive (optional). /meida/usb[1-9] USB drive (optional). ディレクトリ 説明 /mnt This directory is a mount point for a temporarily mounted filesystem. In some distributions, /mnt contains subdirectories intended to be used as mount points for several temporary filesystems. /opt This directory should contain add-on packages that contain static files. /proc This is a mount point for the proc filesystem, which provides information about running processes and the kernel. This pseudo-filesystem is described in more detail in proc(5). /sys This is a mount point for the sysfs filesystem, which provides information about the kernel like /proc, but better structured, following the formalism of kobject infrastructure. /root This directory is usually the home directory for the root user (optional). /run This directory contains information which describes the system since it was booted. Once this purpose was served by /var/run and programs may continue to use it. /sbin Like /bin, this directory holds commands needed to boot the system, but which are usually not executed by normal users. /srv This directory contains site-specific data that is served by this system. /tmp This directory contains temporary files which may be deleted with no notice, such as by a regular job or at system boot up. /usr ディレクトリ 説明 /usr This directory is usually mounted from a separate partition. It should hold only shareable, read-only data, so that it can be mounted by various machines running Linux. /usr/X11R6 The X-Window system, version 11 release 6 (present in FHS 2.3, removed in FHS 3.0). /usr/bin/mh Commands for the MH mail handling system (optional). /usr/bin/X11 is the traditional place to look for X11 executables; on Linux, it usually is a symbolic link to /usr/X11R6/bin. /usr/etc Site-wide configuration files to be shared between several machines may be stored in this directory. However, commands should always reference those files using the /etc directory. Links from files in /etc should point to the appropriate files in /usr/etc. /usr/games Binaries for games and educational programs (optional). /usr/include Include files for the C compiler. /usr/include/bsd BSD compatibility include files (optional). /usr/include/X11 Include files for the C compiler and the X-Window system. This is usually a symbolic link to /usr/X11R6/include/X11. /usr/include/asm Include files which declare some assembler functions. This used to be a symbolic link to /usr/src/linux/include/asm. /usr/include/linux This contains information which may change from system release to system release and used to be a symbolic link to /usr/src/linux/include/linux to get at operating-system-specific information. (Note that one should have include files there that work correctly with the current libc and in user space. However, Linux kernel source is not designed to be used with user programs and does not know anything about the libc you are using. It is very likely that things will break if you let /usr/include/asm and /usr/include/linux point at a random kernel tree. Debian systems don't do this and use headers from a known good kernel version, provided in the libc*-dev package.) /usr/include/g++ Include files to use with the GNU C++ compiler. /usr/lib Object libraries, including dynamic libraries, plus some executables which usually are not invoked directly. More complicated programs may have whole subdirectories there. /usr/libexec Directory contains binaries for internal use only and they are not meant to be executed directly by users shell or scripts. /usr/lib<qual> These directories are variants of /usr/lib on system which support more than one binary format requiring separate libraries, except that the symbolic link /usr/lib<qual>/X11 is not required (optional). /usr/lib/X11 The usual place for data files associated with X programs, and configuration files for the X system itself. On Linux, it usually is a symbolic link to /usr/X11R6/lib/X11. /usr/lib/gcc-lib contains executables and include files for the GNU C compiler, gcc(1). /usr/lib/groff Files for the GNU groff document formatting system. /usr/lib/uucp Files for uucp(1). /usr/local This is where programs which are local to the site typically go. /usr/local/bin Binaries for programs local to the site. /usr/local/doc Local documentation. /usr/local/etc Configuration files associated with locally installed programs. /usr/local/games Binaries for locally installed games. /usr/local/lib Files associated with locally installed programs. /usr/local/lib<qual> These directories are variants of /usr/local/lib on system which support more than one binary format requiring separate libraries (optional). /usr/local/include Header files for the local C compiler. /usr/local/info Info pages associated with locally installed programs. /usr/local/man Man pages associated with locally installed programs. /usr/local/sbin Locally installed programs for system administration. /usr/local/share Local application data that can be shared among different architectures of the same OS. /usr/local/src Source code for locally installed software. /usr/sbin This directory contains program binaries for system administration which are not essential for the boot process, for mounting /usr, or for system repair. /usr/share This directory contains subdirectories with specific application data, that can be shared among different architectures of the same OS. Often one finds stuff here that used to live in /usr/doc or /usr/lib or /usr/man. /usr/share/color Contains color management information, like International Color Consortium (ICC) Color profiles (optional). /usr/share/dict Contains the word lists used by spell checkers (optional). /user/share/dict/words List of English words (optional). /usr/share/doc Documentation about installed programs (optional). /usr/share/games Static data files for games in /usr/games (optional). /user/share/info Info pages go here (optional). /usr/share/local Locale information goes here (optional). /usr/share/man Manual pages go here in subdirectories according to the man page sections. /user/share/misc Miscellaneous data that can be shared among different architectures of the same OS.