Linux File Hierarchy Structure


The Linux File Hierarchy Structure or the Filesystem Hierarchy Standard (FHS) defines the directory structure and directory contents in Unix-like operating systems. It is maintained by the Linux Foundation.
·         In the FHS, all files and directories appear under the root directory /, even if they are stored on different physical or virtual devices.
·         Some of these directories only exist on a particular system if certain subsystems, such as the X Window System, are installed.
·         Most of these directories exist in all UNIX operating systems and are generally used in much the same way; however, the descriptions here are those used specifically for the FHS, and are not considered authoritative for platforms other than Linux.


1. / (Root) : Primary hierarchy root and root directory of the entire file system hierarchy.
·         Every single file and directory starts from the root directory
·         Only root user has the right to write under this directory
·         / root is root user’s home directory, which is not same as /

2. /bin: Essential command binaries that need to be available in single user mode; for all users, e.g., cat, ls, cp.
Contains binary executables
·         Common linux commands you need to use in single-user modes are located under this directory.
·         Commands used by all the users of the system are located here e.g. ps, ls, ping, grep, cp

3. /boot: Boot loader files, e.g., kernels, initrd.
·         Kernel initrd, vmlinux, grub files are located under /boot

4. /dev: Essential device files, e.g., /dev/null.
·         These include terminal devices, usb, or any device attached to the system.

5. /etc: Host-specific system-wide configuration files.
·         Contains configuration files required by all programs.
·         This also contains startup and shutdown shell scripts used to start/stop individual programs.
6. /home: Users’ home directories, containing saved files, personal settings, etc.
·         Home directories for all users to store their personal files.

7. /lib: Libraries essential for the binaries in /bin/ and /sbin/.
·         Library filenames are either ld* or lib*.so.*

8. /media: Mount points for removable media such as CD-ROMs (appeared in FHS-2.3).
·         Temporary mount directory for removable devices.

9. /mnt: Temporarily mounted filesystems.
·         Temporary mount directory where sysadmins can mount filesystems.

10. /opt: Optional application software packages.
·         Contains add-on applications from individual vendors.
·         Add-on applications should be installed under either /opt/ or /opt/ sub-directory.

11. /sbin: Essential system binaries, e.g., fsck, init, route.
·         Just like /bin, /sbin also contains binary executables.
·         The linux commands located under this directory are used typically by system aministrator, for system maintenance purpose.
·         Example: iptables, reboot, fdisk, ifconfig, swapon

12. /srv: Site-specific data served by this system, such as data and scripts for web servers, data offered by FTP servers, and repositories for version control systems.
·         srv stands for service.
·         Contains server specific services related data.

13. /tmp: Temporary files. Often not preserved between system reboots, and may be severely size restricted.
·         Directory that contains temporary files created by system and users.
·         Files under this directory are deleted when system is rebooted.

14. /usr: Secondary hierarchy for read-only user data; contains the majority of (multi-)user utilities and applications.
·         Contains binaries, libraries, documentation, and source-code for second level programs.
·         /usr/bin contains binary files for user programs. If you can’t find a user binary under /bin, look under /usr/bin. For example: at, awk, cc, less, scp
·         /usr/sbin contains binary files for system administrators. If you can’t find a system binary under /sbin, look under /usr/sbin. For example: atd, cron, sshd, useradd, userdel
·         /usr/lib contains libraries for /usr/bin and /usr/sbin
·         /usr/local contains users programs that you install from source. For example, when you install apache from source, it goes under /usr/local/apache2
·         /usr/src holds the Linux kernel sources, header-files and documentation.

15. /proc: Virtual filesystem providing process and kernel information as files. In Linux, corresponds to a procfs mount. Generally automatically generated and populated by the system, on the fly.
·         Contains information about system process.
·         This is a pseudo filesystem contains information about running process. For example: /proc/{pid} directory contains information about the process with that particular pid.
·         This is a virtual filesystem with text information about system resources.

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