Directories and File Systems

Linux and Unix file systems are organised in a hierarchical, tree-like structure. The highest level of the file system is the / or root directory. In the Unix and Linux design philosophy, everything is considered a file - including hard disks, partitions and removable media. This means that all files and directories (including other disks and partitions) exist under the root directory.

For example, /home/pondy/cheeses.html shows the correct full path to the cheeses.html file that exists in the pondy directory which is under the home directory, which in turn, is under the root (/) directory.

Underneath the root (/) directory, there is a set of important system directories that are commonly used across most Linux distributions. The following is a listing of common directories that are directly under the root (/) directory:

• /bin - important binary applications
• /boot - files that are required to boot the computer
• /dev - the device files
• /etc - configuration files, startup scripts, etc...
• /home - local users' home directories
• /lib - system libraries
• /lost+found - provides a lost+found system for files that exist under the root (/) directory
• /media - mounted (loaded) removable media such as CDs, digital cameras, etc...
• /mnt - mounted filesystems
• /opt - provides a location for optional applications to be installed
• /proc - special dynamic directory that maintains information about the state of the system, including currently running processes
• /root - root user home directory, pronounced 'slash-root'
• /sbin - important system binaries
• /srv - provides a location for data used by servers
• /sys - contains information about the system
• /tmp - temporary files
• /usr - applications and files that are mostly available for all users to access
• /var - variable files such as logs and databases

Reference: Ubuntu 8.10 Help Center Directories and FIle Systems