README.md

0x16. C - Simple Shell

In this project we are to create a basic and simple shell, the project is a group project for two and it has seventeen tasks which inlude;

0. Betty would be proud - Write a beautiful code that passes the Betty checks

1. Simple shell 0.1 - Write a UNIX command line interpreter. Usage: simple_shell * Your Shell should:

    * Display a prompt and wait for the user to type a command. A command line always ends with a new line.
    * The prompt is displayed again each time a command has been executed.
    * The command lines are simple, no semicolons, no pipes, no redirections or any other advanced features.
    * The command lines are made only of one word. No arguments will be passed to programs.
    * If an executable cannot be found, print an error message and display the prompt again.
    * Handle errors.
    * You have to handle the “end of file” condition (Ctrl+D)
   

   You don’t have to:

    * use the PATH
    * implement built-ins
    * handle special characters : ", ', `, \, *, &, #
    * be able to move the cursor
    * handle commands with arguments
    * execve will be the core part of your Shell, don’t forget to pass the environ to it…
   

2. Simple shell 0.2

Simple shell 0.1 +

* Handle command lines with arguments

3. Simple shell 0.3

Simple shell 0.2 +

* Handle the PATH
* fork must not be called if the command doesn’t exist

4. Simple shell 0.4

Simple shell 0.3 +

* Implement the exit built-in, that exits the shell
* Usage: exit
* You don’t have to handle any argument to the built-in exit

5. Simple shell 1.0

Simple shell 0.4 +

* Implement the env built-in, that prints the current environment

6. Simple shell 0.1.1

Simple shell 0.1 +

* Write your own getline function
* Use a buffer to read many chars at once and call the least possible the read system call
* You will need to use static variables
* You are not allowed to use getline

You don’t have to:

* be able to move the cursor

7. Simple shell 0.2.1

Simple shell 0.2 +

* You are not allowed to use strtok

8. Simple shell 0.4.1

Simple shell 0.4 +

* handle arguments for the built-in exit
* Usage: exit status, where status is an integer used to exit the shell

9. setenv, unsetenv

Simple shell 1.0 +

Implement the setenv and unsetenv builtin commands

setenv
	* Initialize a new environment variable, or modify an existing one
	* Command syntax: setenv VARIABLE VALUE
	* Should print something on stderr on failure
unsetenv
	* Remove an environment variable
	* Command syntax: unsetenv VARIABLE
	* Should print something on stderr on failure

10. cd

Simple shell 1.0 +

Implement the builtin command cd:

* Changes the current directory of the process.
* Command syntax: cd [DIRECTORY]
* If no argument is given to cd the command must be interpreted like cd $HOME
* You have to handle the command cd -
* You have to update the environment variable PWD when you change directory
man chdir, man getcwd

11. ;

Simple shell 1.0 +

* Handle the commands separator ;

12. && and ||

Simple shell 1.0 +

* Handle the && and || shell logical operators

13. alias

Simple shell 1.0 +

Implement the alias builtin command
	* Usage: alias [name[='value'] ...]
	* alias: Prints a list of all aliases, one per line, in the form name='value'
	* alias name [name2 ...]: Prints the aliases name, name2, etc 1 per line, in the form name='value'
	* alias name='value' [...]: Defines an alias for each name whose value is given. If name is already an alias, replaces its value with value

14. Variables

Simple shell 1.0 +

* Handle variables replacement
* Handle the $? variable
* Handle the $$ variable

15. Comments

Simple shell 1.0 +

* Handle comments (#)

16. File as input

Simple shell 1.0 +

* Usage: simple_shell [filename]
* Your shell can take a file as a command line argument
* The file contains all the commands that your shell should run before exiting
* The file should contain one command per line
* In this mode, the shell should not print a prompt and should not read from stdin