| Linux Shell Scripting Tutorial (LSST) v1.05r3 | ||
| Chapter 1: Introduction : Linux Shell basics | ||
| | ||
Computers understand the language of zeros and ones known as binary language. In the early days of computing, instructions were provided using binary language, which is difficult for all of us humans to read and write. Therefore, in an operating system there is a special program called the shell. The shell accepts human readable commands and translates them into something the kernel can read and process.
The shell is a user program or it is an environment provided for user interaction. It is a command language interpreter that executes commands read from the standard input device (keyboard) or from a file.
Shell is not part of system kernel, but uses the system kernel to execute programs, create files etc.
Several shells are available for Linux including:
| Shell Name | Developed by | Where | Remark |
| BASH ( Bourne-Again SHell ) | Brian Fox and Chet Ramey | Free Software Foundation | Most common shell in Linux. It's Freeware shell. |
| CSH (C SHell) | Bill Joy | University of California (For BSD) | The C shell's syntax and usage are very similar to the C programming language. |
| KSH (Korn SHell) | David Korn | AT & T Bell Labs | -- |
| TCSH | See the man page. Type $ man tcsh | -- | TCSH is an enhanced but completely compatible version of the Berkeley UNIX C shell (CSH). |
To find all of the available shells in your system, type the following command:
$ cat /etc/shells
Note that each shell does the same job, but each understands different command syntax and provides different built-in functions.
Under MS-DOS, the shell name is COMMAND.COM which is also used for the same purpose, but it is not as powerful as our Linux Shells are!
The shell provides an interface to Linux where you can type or enter commands using the keyboard. It is known as the command line interface (CLI).
To find out your current shell type following command:
$ echo $SHELL
$ ps $$
| | ||
| What Kernel Is? | How to use Shell | |