Folder locations Once you start working in Ubuntu, you'll want to know where to save your files. Ubuntu gives you a personal home directory, with subdirectories already set up for Documents, Music, Pictures, Videos and Downloads. There's also a Public folder: files stored here will be available to anyone who logs on to your PC.
Drivesand devices. Ubuntu can read and write disks and partitions that use the familiar FAT32 and NTFS formats, but by default it uses a more advanced format called Ext4. This format is less likely to lose data in the event of a crash, and it can support large disks or files. The downside is that Windows can't read it – something to be aware of if you want to share files across a dual-boot PC. Another difference is the way the file system is organized. In Windows, each drive in your system has its directory hierarchy – so, for example, a folder on a USB flash drive might be addressed as "E: Files \Test file.doc". In Ubuntu there's a single root directory for the entire system, referred to simply as "I" (a "regular" slash, not a backslash as used by Windows), and all disks and devices appear within this hierarchy. You can see how this works by opening the Ubuntu File Manager and clicking on File System to view the root directory. You'll see a folder called /media, and if you've installed Ubuntu alongside a Windows installation, there will be a link within this folder to your Windows partition (your files are in /host if you've installed Ubuntu on the same partition as Windows, using the Wubi installer). Plug in a USB flash drive and that will appear here too. There are many other top-level directories besides /media, but unless you get into advanced system administration, only a few are worth knowing about. (Even so, most first-time users of Ubuntu probably won't be venturing anywhere near them.) The /etc directory contains hardware-specific settings, where you'll find configuration files for things such as graphics cards and printers. /usr is where most apps and libraries go when you install them, and /home contains the home folders for all the users on the system.
Virtual folders. As the contents of the /media directory demonstrate, a directory in Ubuntu may not be a "real" directory: it could be a link to a different device or to a different location on the same disk. This approach takes some getting used to, but it adds a level of flexibility. In schools and businesses that run Unix-type systems, for example, it's common for /home to be not a regular directory but a link to a different disk, or even a remote network location. This makes it easy to back up users' data or move it to a different PC, independently to the rest of the OS. (This type of virtual folder is called a "mount point".) If you want to reorganize your own directories, you'll find full instructions in the online Ubuntu documentation at http://help.ubuntu.com. Be warned, though, you'll need to use the Terminal, and there are some technical issues involved. One other thing to note is that in Ubuntu, filenames and paths are case sensitive – so a folder called "data" isn't the same as one called "Data". Remember that, or it will trip you up!
File permissions. A final important difference between the Windows and Ubuntu file systems relates to file permissions. In Windows, you can access almost any file or folder on your system — although there are a few circumstances when you might need to take ownership of a system file. Ubuntu is stricter. System and configuration files are owned by an administrator account called "root", and when you're logged in under your own name, you have only limited access to things outside of your home directory. That's normal, and it's for your own safety — it makes it almost impossible for you to accidentally mess up your system. These restrictions also apply to programs you run under that account, which makes Ubuntu resistant to Trojans and other sorts of malware. If you do need to edit system files, you can do so using a Terminal command called "sudo", which temporarily promotes you to a " superuser". You'll find everything you need to know about File Permissions and the sudo command in the online documentation.
Source of Information : PC Pro -April 2011