Unix Shell

• Unix is a layered operating system.
• The OS not allow applications accessing the hardware directly. 
• The shell acts as a command interpreter.
• It takes each command and passes it to the operating system kernel to be acted upon. And then displays the results of this operation

Relationship for Kernel,Shell and Application

Features provided by the shell

Types of shell

There are several different shells available for Unix. The most popular are described here.

•     Bourne shell (sh) 
•     C shell (csh)
•     Korn shell (ksh) 
•     Bourne Again Shell (bash)

Unix Command

• A command is a program that tells the Unix system to do something. 
• Usually has the form: command [options] [arguments]
• Commands are case sensitive. command and Command are not the same.
• Options and syntax for a command are listed in the  man page

Navigation and Directory Control Commands

File Maintenance Commands

Miscellaneous commands