batusengezer/minishell

A minimalist shell implementation in C, as part of the school 42's core curriculum. Documented by Stefano Lombardo

Minishell

A 'simple' Unix shell in C for the School 42 curriculum.

Table of Contents

• Introduction
• Features
• Installation & Usage
• Constratints
• Architecture
• Contributors

Introduction

Minishell is a simple Unix shell developed in C as part of the School 42 curriculum. It is a collaborative project developed by Batu and Stefano. The program is being developed with certain constraints: - the strictly adherence to the so called Norm, which imposes certain (at times questionable) limitations such as a maximum function length of 25 lines, the prohibition of for-loops, and more, a restricted set of allowed functions.

Features

• Display a prompt when waiting for a new command.
• Working history.
• Input redirection (<) and output redirection (> & >>)
• Handling of environment variables (like $PATH)
• Signal management for ctrl-C, ctrl-D and ctrl-\
• Built-in commands support (echo, cd, pwd, export, unset, exit, pwd)
• Quotation handling for both single (') and double (") quotes
• Piping between commands using |
• Expansion for $? to show exit status of the last executed command
• ...

Installation & Usage

• Clone the repository to your local machine: git clone https://github.com/552020/minishell.git
• Navigate to the relevant directory cd minishell
• Compile the project with make
• Run minishell: ./minishell

Once Minishell is started, you can interact with it like any traditional Unix shell. Enter commands, use redirections (<, >, >>), and pipe commands.

Constraints

Allowed Functions

For the development of Minishell, we were restricted to using a specific set of functions. The permitted external functions are:

• I/O Functions: readline, rl_clear_history, rl_on_new_line, rl_replace_line, rl_redisplay, add_history, printf, write, read, open, close
• Memory Management: malloc, free
• Process Management: fork, wait, waitpid, wait3, wait4, exit, execve
• Signal Handling: signal, sigaction, sigemptyset, sigaddset, kill
• File and Directory Handling: access, getcwd, chdir, stat, lstat, fstat, unlink, dup, dup2, pipe, opendir, readdir, closedir
• Error Handling: strerror, perror
• Terminal Control: isatty, ttyname, ttyslot, ioctl, getenv, tcsetattr, tcgetattr, tgetent, tgetflag, tgetnum, tgetstr, tgoto, tputs

In addition to the aforementioned functions, we were permitted to use our self-coded libft library. This library, a previous project from the School 42 curriculum, contains a set of 40 functions that serve as replacements for common C library functions like strcpy, calloc, and so on.

The Norm

The most notable restrictions of the norm are:

• the 42 header should be present in every file
• functions must not exceed 25 lines
• global variables are generally not allowed
• the use of ceratin keywords as for, do...while, switch, case, and goto.
• Comments are not permitted within functions​​.
• Blank spaces within a function are not allowed, except between variable declarations and the rest of the code​​.
• All variables must be declared and set at the top of the function​​.

The entire set of rules and guidelines established by the Norm can be found in the document en.norm.pdf within the repository.

Architecture