Linux File system hierarchy

Linux File system hierarchy

Linux has only the parent directory (/) and all other directories are available under this.

• / (Root):

• Primary hierarchy root and root directory of the entire file system hierarchy.

• The only root user has the right to write under this directory

• /root is the root user’s home directory, which is different from /

• /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.

• Example: /etc/resolv.conf, /etc/logrotate.conf.

• /home:

• Users’ home directories, containing saved files, personal settings, etc.

• Home directories for all users to store their personal files.

• example: /home/kishlay, /home/kv

• /var:

• Variable Value file

• Files that have an unexpected size and whose content is expected to change continuously during normal operation of the system are stored here.

• For example, log files, spool files and cache files.

• /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.

• /lib:

• Libraries essential for the binaries in /bin/ and /sbin/.

• Library filenames are either ld* or lib*.so.*

• Example: ld-2.11.1.so, libncurses.so.5.7

• /lib64:

• Same as /lib but is for 64 bit

• /temp:

• 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.

• /mnt:

• Temporarily mounted filesystems.

• Temporary mount directory where sysadmins can mount filesystems.

• /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.

• Example, /srv/cvs contains CVS related data.

• /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.

• /dev:

• Essential device files, e.g., /dev/null.

• These include terminal devices, usb, or any device attached to the system.

• Example: /dev/tty1, /dev/usbmon0

• /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. For example: /proc/uptime

• /bin:

• Contains binary executables

• Commands used by all the users of the system are located here e.g. ps, ls, ping, grep, cp

• /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 administrator, for system maintenance purpose.

• Example: iptables, reboot, fdisk, ifconfig, swapon

• /media:

• Mount points for removable media such as CD-ROMs (appeared in FHS-2.3).

• Temporary mount directory for removable devices.

• Examples, /media/cdrom for CD-ROM; /media/floppy for floppy drives; /media/cdrecorder for CD writer

• /boot:

• Boot loader files, e.g., kernels, initrd

• Kernel initrd, vmlinux, grub files are located under /boot