Explanation of the Unix File System Hierarchy

The structure of a Unix or Linux file system can be quite confusing to newbies. This post touches on the main directories found on a typical Unix or Linux system.

For more in depth information, I recommend the file-hierarchy man page from Arch Linux: https://jlk.fjfi.cvut.cz/arch/manpages/man/file-hierarchy.7.

/ - root

• The root of the entire file system hierarchy
• Not to be confused with /root, the home directory for the root user

/bin - binaries

• Command binaries available in single-user mode, or for all users
• Examples: cat, ls, cp, ping

/boot - boot loader

• Contains boot loader files
• Examples: kernels, initrd

/dev - device files

• A device file allows for device drivers to be treated like ordinary files (“everything in Unix is a file”)
• The two general types of device files are character special files and block special files
• Examples: /dev/null, /dev/random, /dev/full, /dev/tty

/etc - config files

• Contains static config files used by the system
• Linux restricts binaries from being placed in /etc
• Examples: /etc/shadow, /etc/passwd, /etc/crontab, /etc/magic

/home - user’s home directories

• Home directories for non-root users
• Contains saved files and personal settings

/lib - libraries

• Contains essential shared libraries needed by programs in /bin and /sbin

/media - removable media

• The default mount point for removable devices, such as USBs and CDs

/mnt - mounted devices

• Commonly used by system admins as a temporary file system mounting point

/opt - optional programs

• Optional application software and packages
• Good location for user installed programs

/proc - process information

• A virtual file system for displaying process and kernel information as files
• The files are generated automatically on the fly when they are called
• Examples: /proc/cpuinfo, /proc/stat, /proc/self

/root - root’s home directory

• Home directory for the root user
• Not readable or writeable by other users

/run - run-time variable data

• Information about the running system since last boot, for example, currently logged in users and running daemons

/sbin - system binaries

• Contains essential utilities for the system
• Examples: /sbin/init, /sbin/mkswap, /sbin/sfdisk

/srv - server data

• Data served by this system, such as web or FTP servers

/tmp - temporary files

• For temporary files that will be erased when the system reboots

/usr - user programs

• Holds executables, libraries, and shared resources that are not system critical
• Non-essential binaries are in /usr/bin and non-essential system binaries are in /usr/sbin

/var - variable files

• For files whose content is expected to change regularly
• Examples: /var/log, /var/spool, /var/mail