BASIC-SHELL

Simple Shell implementation

##Introduction The Shell or Command Line Interpreter is a fundamental User Interface to an Operating System.

####Features

1. cd Changes the current default directory to . If the argument is not present, the current directory is reported. If the directory doesn’t exist an appropriate error message is reported. This command also changes the PWD environment variable.

2. clr Clears the screen.

3. dir Lists the contents of directory .

4. environ Lists all the environment strings.

5. echo Display on the display followed by a new line. ( Multiple spaces/tabs are reduced to a single space).

6. pause Pause Operation of shell until ‘Enter ’ is pressed.

7. help Displays User Manual.

8. quit Quits the shell.

9. The shell environment contains shell=/myshell where /myshell is full path for the shell executable (not a hardwired path back to your directory, but the one from which it was executed).

10. The shell is be able to take its command line input from a file. That is, if the command line is invoked with a command line argument: myshell batchfile then batchfile is assumed to contain a set of command lines for the shell to process. When the endoffile is reached, the shell exits.

####How To Use

1. Just compile the main.c with gcc.

2. Run the program and the shell is ready to be used.