minishell

A simplified Bash-like shell written in C, using GNU Readline. Parses and runs pipelines with redirections, heredocs and environment expansion, and implements the core shell builtins. 1337 (42 Network) project.

What it does

• Interactive prompt with history (readline/add_history).
• Pipelines: cmd1 | cmd2 | ..., arbitrary length.
• Redirections: <, >, >>, and here-documents (<<) with a delimiter, including quote-aware delimiter handling.
• Quoting & expansion: single/double quotes, $VAR and $? expansion, word splitting after expansion.
• Builtins: cd, pwd, echo, env, export, unset, exit.
• External commands: resolved against PATH, run via fork/execve.
• Signals: Ctrl-C, Ctrl-\ and Ctrl-D handled to match Bash behavior (new prompt line, ignored in the shell, exit on empty input).
• Exit status ($?) tracked across builtins and external commands.

How it works

readline -> clean_input (trim + spread_tokens)
         -> lexer   (raw string -> list of t_command, each with its own token list)
         -> parser  (syntax validation, expansion, redirection/heredoc collection)
         -> executer (forks per command, wires pipes/redirections, runs builtins in-process)

• src/lexer/ turns the raw input line into tokens (words, |, <, >, >>, << + their file/delimiter) and groups them into one t_command node per pipeline stage.
• src/parser/ (parser.c, expander.c, parse_errors.c) checks the token list for syntax errors, expands variables and quotes, and collects the redirection files and heredoc delimiters.
• src/executer/ (executer.c, set_redirections.c, set_heredocs.c, get_path.c) sets up pipes and file descriptors, resolves the binary path, and forks one child per command in the pipeline; a builtin run alone (no pipe) executes directly in the shell process so cd/export/exit affect the shell's own state.
• src/builtins/ implements each builtin against a linked-list environment (t_env) kept in sync with envp.

My part

Built with M'Hammed Boukelalen. I worked on the parser, expander, executer, heredocs, redirections and builtins (main.c, parser.c, expander.c, executer.c, set_heredocs.c, set_redirections.c, get_path.c, src/builtins/).

Build & run

make            # builds libft, then ./minishell (cc -Wall -Wextra -Werror, links -lreadline)
make start      # clears the screen and runs ./minishell
./minishell

What I learned

• Writing a token-list parser with syntax error checks, rather than a recursive-descent design.
• Process orchestration for pipelines: creating N pipes, duplicating file descriptors per child, and avoiding fd leaks/deadlocks.
• Handling heredocs correctly under signals (Ctrl-C during heredoc input).
• The difference between builtins that must run in the parent shell (cd, export, exit, unset) versus in a forked child.