JohnnyJumper / minishell

Minishell

The first step toward creating a shell. This project consists in writing a mini-shell able to read to evaluate basic command lines from a user. The reading part implies trivial lexical and syntactic analyses of the command line, and the evaluation part implies to locate the requested binary on the computer and run it, or running the corresponding code in case of a built in functionality of the shell.

General Instructions

• The executable file must be named minishell.
• You must submit a Makefile. That Makefile needs to compile the project and must contain the usual rules. It can only recompile the program if necessary.
• Your project must be written in C in accordance with the Norm.
• You have to handle errors in a sensitive manner. In no way can your program quit in an unexpected manner (Segmentation fault, bus error, double free, etc).
• Your program cannot have memory leaks.
• You’ll have to submit at the root of your folder, a file called author containing your username followed by a ’\n’
• Within your mandatory part you are allowed to use the following functions:

    ◦ malloc, free 
    ◦ access
    ◦ open, close, read, write
    ◦ opendir, readdir, closedir
    ◦ getcwd, chdir
    ◦ stat, lstat, fstat
    ◦ fork, execve
    ◦ wait, waitpid, wait3, wait4
    ◦ signal, kill
    ◦ exit 

• You are allowed to use other functions to carry out the bonus part as long as their use is justified during your defence. For example, to use tcgetattr is justified in certain case, to use printf because you are lazy isn’t. Be smart!

Mandatory part

• You must program a mini UNIX command interpreter.
• This interpreter must display a prompt (a simple "$> " for example) and wait till you type a command line, validated by pressing enter.
• The prompt is shown again only once the command has been completely executed.
• The command lines are simple, no pipes, no redirections or any other advanced functions.
• The executable are those you can find in the paths indicated in the PATH variable.
• In cases where the executable cannot be found, it has to show an error message and display the prompt again.
• You must manage the errors without using errno, by displaying a message adapted to the error output.
• You must deal correctly with the PATH and the environment (copy of system char **environ).
• You must implement a series of builtins: echo, cd, setenv, unsetenv, env, exit.
• You can choose as a reference whatever shell you prefer.