Filesystem Hierarchy Standard

The Filesystem Hierarchy Standard (FHS) defines the main directories and their contents in Linux and other Unix-like computer operating systems.

All files and directories appear under the root directory /, even if stored on different physical devices. Directories defined by the FHS include:

• /bin/ Essential command binaries for all users (e.g., cat, ls, cp)
• /boot/ Boot loader files (e.g., kernels, initrd)
• /dev/ Essential devices (e.g., /dev/null)
• /etc/ Host-specific system-wide configuration files
  • /etc/opt/ Configuration files for /opt/
  • /etc/X11/ (optional) Configuration files for the X Window System
  • /etc/sgml/ (optional) Configuration files for SGML
  • /etc/xml/ (optional) Configuration files for XML
• /home/ (optional) Users' home directories
• /lib/ Libraries essential for the binaries in /bin/ and /sbin/
• /mnt/ Temporarily mounted filesystems
• /media/ Mountpoints for removable media such as CD-Roms (appeared in FHS-2.3)
• /opt/ Static application software packages
• /proc/ Virtual filesystem documenting kernel status, mostly text files (e.g., uptime, network)
• /root/ (optional) Home directory for the root user
• /sbin/ Essential binaries for root (e.g., init, route, ifup)
• /tmp/ (optional) Temporary files
• /usr/ Secondary hierarchy for shareable, read-only data
  • /usr/bin/, /usr/lib/, /usr/sbin/ Same as for top-level hierarchy
  • /usr/include/ Standard include files
  • /usr/share/ Architecture-independent data
  • /usr/src/ (optional) Source code
  • /usr/X11R6/ (optional) X Window System, Version 11 Release 6
  • /usr/local/ Tertiary hierarchy for local data installed by the system administrator
• /var/ Variable files, such as logs and temporary files