Ubuntu directory structure...

In the *nix operating systems, the tree style of file systems are there from time immemorial. In fact the idea of a inverted tree directory system or all filesystems originated with Unix.

The root of the tree is called "root directory" here and is the top level directory, and all its subdirectories make up the directory hierarchy. This is different as compared to Windows wherein there are drives. Especially diff since each diff hardware device has its own dir tree with its own root directory. In Unix there is only one root dir. Everything else, falls under that tree...

Here's a summary of the standard directories found on a typical Unix/Linux system. Current reference being Ubuntu.

• /bin - binary applications (most of your executable files)

• /boot - files required to boot (such as the kernel, etc)

• /dev - your devices (everything from drives to displays)

• /etc - just about every configuration file for your system

• /etc/profile.d - contains scripts that are run by /etc/profile upon login.

• /etc/rc.d - contains a number of shell scripts that are run on bootup at different run levels. There is also typically an rc.inet1 script to set up networking (in Slackwar), an rc.modules script to load modular device drivers, and an rc.local script that can be edited to run commands desired by the administrator, along the lines of autoexec.bat in DOS.

• /etc/rc.d/init.d - contains most of the initialization scripts themselves on an rpm-based system.

• /etc/rc.d/rc*.d - where “*'’ is a number corresponding to the default run level. Contains files for services to be started and stopped at that run level. On rpm-based systems, these files are symbolic links to the initialization scripts themselves, which are in /etc/rc.d/init.d.

• /etc/skel - directory containing several example or skeleton initialization shells. Often contains subdirectories and files used to populate a new user’s home directory.

• /etc/X11 - configuration files for the X Window system

• /home - locally stored user files and folders

• /lib - system libraries (similar to Program Files)

• /lost+found - lost and found for lost files

• /media - mounted (or loaded) devices such as cdroms, digital cameras, etc.

• /mnt - mounted file systems

• /opt - location for “optionally” installed programs

• /proc - dynamic directory including information about and listing of processes

• /root - “home” folder for the root user

• /sbin - system-only binaries (see /bin)

• /sys - contains information about the system

• /tmp - temporary files

• /usr - applications mainly for regular users

• /var - mainly logs, databases, etc.

• /usr/local/bin - the place to put your own programs. They will not be overwritten with upgrades.

• /usr/share/doc - documentation.

Some content shamelessly borrowed from this page :Linux or ubuntu Directory structure