Minishell - 42 School Project - 1337 KH

A custom Unix shell written in C, replicating core features of Bash.
Built from scratch to manage processes, parse and execute commands, handle redirections, pipes, environment variables, and more.

Minishell is one of the most complex projects in the 42 curriculum.
It requires an in-depth understanding of Unix internals: from lexing and parsing shell input, to managing low-level system calls like fork, execve, pipe, and dup2.

This project was developed in collaboration with sbaghdad, where:

• Oussama FARAH/oufarah focused on execution, Built-in commands, pipes, environment, exit status, and memory management.
• Soufiane Baghdadi/sbaghdad handled expand, parsing, redirections, signal handling, syntax validation, and argument expansion logic.

minishell/
├── builtins/ # echo with option -n, cd, pwd, export, unset, env, exit
├── exec/ # execution, piping, forking
├── lexer/ # tokenizing input
├── parser/ # syntax tree and command structure
├── env/ # environment variable management
├── signals/ # signal handling
├── garbage/ # custom garbage collector
├── minishell.c # main shell loop
└── libft/ # custom C standard library same functions in libft

• ✅ Custom interactive shell prompt
• ✅ Environment variable expansion ($HOME, $USER, etc.)
• ✅ Built-in commands:
  • echo, cd, pwd, export, unset, env, exit
• ✅ Input/output redirection:
  • <, >, >>
• ✅ Pipe support: ls | grep txt | wc -l
• ✅ Quote handling: ', "
• ✅ Exit status tracking with $?
• ✅ Heredoc (<<) support
• ✅ Signal handling: Ctrl+C, Ctrl+\
• ✅ Custom garbage collector for memory management
• ✅ Norminette-compliant (42 style guide)

Minishell executes a cycle of:

1. Reading input from the user.
2. Tokenizing and parsing the input into a command structure.
3. Executing the parsed commands, managing forks and redirections.
4. Cleaning up and returning to prompt.

# Clone the repository
git clone https://github.com/oussama-fa/minishell_42.git
cd minishell_42

# Compile
make

Run the shell:

./minishell

Try a few commands:

minishell➤ echo -n Hello World
minishell➤ export NAME=oussama
minishell➤ echo $NAME
minishell➤ ls -l | grep .c | wc -l
minishell➤ cat << EOF
minishell➤ export a="ls   -la"
minishell➤ $a
total 100
drwxr-xr-x 5 oufarah 2024_khouribga   148 Jun 26 16:47 .
drwxr-xr-x 7 oufarah 2024_khouribga    96 Jun 26 16:27 ..
drwxr-xr-x 2 oufarah 2024_khouribga  4096 Jun 26 16:47 exec
-rw-r--r-- 1 oufarah 2024_khouribga  1928 Jun 26 16:27 garbage.c
drwxr-xr-x 7 oufarah 2024_khouribga   119 Jun 26 16:47 .git
-rw-r--r-- 1 oufarah 2024_khouribga  2420 Jun 26 16:27 Makefile
-rwxr-xr-x 1 oufarah 2024_khouribga 62144 Jun 26 16:47 minishell
-rw-r--r-- 1 oufarah 2024_khouribga  2295 Jun 26 16:27 minishell.c
-rw-r--r-- 1 oufarah 2024_khouribga  8517 Jun 26 16:27 minishell.h
drwxr-xr-x 3 oufarah 2024_khouribga  4096 Jun 26 16:47 parse
-rw-r--r-- 1 oufarah 2024_khouribga  2920 Jun 26 16:47 README.md

• Language: C

• Parsing: Handles quotes, redirections, expansions, pipes

• Core Syscalls: fork, execve, pipe, dup2, wait, access

• Built-in Management: Handled in separate logic without forking

• Environment: Custom linked list replacing envp

• Memory: Leak-free using custom garbage collector and handle file descrepter leaks

• Signal Handling: Custom behavior for SIGINT, SIGQUIT

• Writing a parser that correctly interprets complex shell syntax

• Forking and managing multiple processes with file descriptor safety

• Managing memory leaks in dynamic command structures

✅ 42 Norminette Compliant

❌ No system() or other forbidden functions

✅ Fully leak-free (tested with valgrind)

✅ Behavior replicates Bash as much as possible

👨‍💻 Oussama FARAH

• ✉️ Email: oussama05farah@gmail.com
• 📱 Instagram: @oussama._.farah

👨‍💻 Soufiane Baghdadi

• Github: sbaghdad