Minishell

A small UNIX shell implemented as part of the 42 curriculum. It provides a Bash-like interactive prompt with support for pipelines, I/O redirections, heredocs, environment variables, and a subset of built-in commands.

Features

• Interactive prompt

  • Custom prompt: Minishell >>
  • Keeps running until exit is called or end-of-file (Ctrl-D) is received.

• Command execution

  • Run external programs using the PATH environment variable.
  • Execute commands using absolute or relative paths.
  • Multiple commands connected with pipelines: cmd1 | cmd2 | cmd3.

• Redirections

  • Input redirection: < file
  • Output redirection (truncate): > file
  • Output redirection (append): >> file
  • Heredoc: << LIMITER with environment expansion in the here-document body.

• Environment handling

  • Internal copy of the parent environment.
  • Variable expansion for $VAR and $? in command lines.
  • Export / unset variables via built-in commands.

• Built-ins

  • echo with -n option.
  • cd with HOME and OLDPWD support.
  • pwd
  • export
  • unset
  • env
  • exit with numeric status handling.

• Signals

  • Ctrl-C (SIGINT) clears the current line, prints a new prompt and sets the exit status to 130.
  • SIGQUIT is ignored in the main shell loop.

Dependencies

• A Unix-like environment with:
  • gcc
  • make
  • The readline library (headers and development library)
• The project already includes:
  • Libft-42/ (custom libc-like utilities)
  • ft_printf/ (printf implementation)
  • get_next_line/ (line reader used for heredocs)

Make sure the READLINE path in the root Makefile matches your system. By default it is configured for Homebrew on macOS:

READLINE = -I/Users/$(USER)/homebrew/opt/readline/include \
           -L/Users/$(USER)/homebrew/opt/readline/lib

Adapt this variable if your readline installation is located elsewhere.

Build

From the project root:

make

This will:

• Compile all Minishell sources.
• Build Libft-42 and ft_printf.
• Link everything into the minishell executable.

Cleanup targets:

make clean   # remove object files (including in Libft-42 and ft_printf)
make fclean  # clean + remove the minishell binary and library archives
make re      # full rebuild

Run

After building:

./minishell

You will see the prompt:

Minishell >> 

Type commands as you would in a simple Bash-like shell.

• End-of-file (Ctrl-D) exits the shell.
• exit [status] exits with the given status (0–255).
• $? reflects the exit status of the last executed pipeline or built-in.

Usage examples

# basic commands
ls -la
echo "Hello, world"

# echo with -n
echo -n "no trailing newline"

# change directory
cd /tmp
pwd

# environment
export FOO=bar
echo $FOO
unset FOO
env

# redirections
echo "hello" > out.txt
cat < out.txt
echo "append" >> out.txt

# pipelines
cat /etc/passwd | grep bash | wc -l

# heredoc
cat << EOF
line 1
value: $HOME
EOF

Project structure

• main.c
  Main loop: initialization, signal setup, readline prompt, parsing and execution.

• parsing.c, parsing_quotes.c, cleaning_quotes.c
  Syntax checks for pipes/redirections, quote validation and quote removal.

• replace_env_vars.c, get_env.c, shellvl.c
  Environment duplication, $VAR / $? expansion, and SHLVL management.

• tokenize_cmds.c, mini_split.c
  Split the input line into commands (separated by |) and words, respecting quotes.

• setting_redirections.c, check_redirections.c
  Detect and extract redirections (<, >, >>, <<) and their target files.

• execute_red.c, execute_herdoc.c, expand_herdoc.c
  Apply I/O redirections and implement heredoc behavior.

• execution_cmd_pipes.c, execution_cmd_pipes_utils.c
  Execute pipelines with fork, dup2, and execve, and track child exit statuses.

• builtins.c, builtins_utils.c, echo.c, export.c, unset.c
  Implementation of all shell built-ins.

• Libft-42/, ft_printf/, get_next_line/
  Supporting libraries.

Notes

This Minishell is designed to satisfy the 42 school project requirements and to emulate a subset of Bash behavior. It focuses on the features described above and does not aim to be feature-complete compared to Bash.

Authors

• suibrahi
• ahibrahi