Here is some basic information about Linux.

Linux is basically a UNIX operating system, it is a open source OS which is easily available in market, Linux is made with only one thought in mind :- Everything is a file.
Means almost everything you do on a computer involves one or more files stored locally or on a network. So Linux's lowest file system folder is root / which contains the following folders:

/bin, /boot, /dev, /etc, /home, /lib, /mnt, /opt, /usr, /var, /proc

there are three kind of permissions in Linux-

1. Read
2. Write
3. Execute

To learn Linux, you need to learn the shell command line in a terminal emulator.

Pressing CTRL+ALT+F1 to CTRL+ALT+F6 gives you the console command shell windows, whereas  CTRL+ALT+F7 gives you the graphical interface. Or u can use xterm for small command window . File names in Linux, like Unix, are case sensitive. The file names "File1" and "file1" refer to different files.

Following are different commands and permissions on Linux which are also known as shell commands are listed below.

1. ls = ls lists the files in the current working folder. Ex ls help will give list of command we can use with ls .
2. pwd = it is used to display the present current directory.
3. cd = is used to change the directory.
4. .. = is used to go one down folder.
5. chmod = Make a file executable.
6. df - view file system disk space usage.
7. du - View the space used by files and folders.
8. mkdir - makes folders
9. rmdirThe command rmdir removes folders.
10. passwd - changes your login password