> whatis hier
hier (7) - Description of the file system hierarchy
> man hier
A typical Linux system has, among others, the following directories:
/ This is the root directory. This is where the whole tree starts.
/bin This directory contains executable programs which are needed in single user mode and to bring the system up or repair it.
/boot Contains static files for the boot loader. This directory only holds the files which are needed during the boot process. The map
installer and configuration files should go to /sbin and /etc.
/dev Special or device files, which refer to physical devices. See mknod(1).
/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.
/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.
/lib This directory should hold those shared libraries that are necessary to boot the system and to run the commands in the root filesystem.
/media This directory contains mount points for removable media such as CD and DVD disks or USB sticks.
/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-file system
is described in more detail in proc(5).
/root This directory is usually the home directory for the root user (optional).
/sbin Like /bin, this directory holds commands needed to boot the system, but which are usually not executed by normal users.
/usr This directory is usually mounted from a separate partition. It should hold only sharable, read-only data, so that it can be mounted by
various machines running Linux.
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.
Replaced by /usr/share/doc.
Site-wide configuration files to be shared between several machines may be stored in this directory. However, commands should always ref‐
erence those files using the /etc directory. Links from files in /etc should point to the appropriate files in /usr/etc.
Include files for the C compiler.
Object libraries, including dynamic libraries, plus some executables which usually are not invoked directly. More complicated programs may
have whole subdirectories there.
This is where programs which are local to the site typically go.
Binaries for programs local to the site.
Configuration files associated with locally installed programs.
/var This directory contains files which may change in size, such as spool and log files.
This directory is superseded by /var/log and should be a symbolic link to /var/log.
Reserved for historical reasons.
Data cached for programs.
Variable state information for programs.
Variable data for /usr/local.
Lock files are placed in this directory. The naming convention for device lock files is LCK..<device> where <device> is the device’s name
in the filesystem. The format used is that of HDU UUCP lock files, that is, lock files contain a PID as a 10-byte ASCII decimal number,
followed by a newline character.
Miscellaneous log files.
Run-time variable files, like files holding process identifiers (PIDs) and logged user information (utmp). Files in this directory are
usually cleared when the system boots.
Spooled (or queued) files for various programs.
The Filesystem Hierarchy Standard