A basic Bash-style shell implementation

Minishell

README en Español

Minishell is a 42 School project that implements the basic features of a shell like Bash.
This version includes all mandatory requirements, the bonus, and some additional features.

✨ Features

Core Functionality

• Interactive command line: Clean prompt with command history
• Command execution: PATH resolution, absolute/relative execution
• Process management: Fork/exec model with proper signal handling
• Environment variables: Full support for variable expansion and manipulation
• I/O redirection: Input/output redirection with append mode
• Pipes: Command chaining with pipe operators
• Heredoc: Advanced input redirection mechanisms
• Syntax checking: Detection and reporting of syntax errors

Advanced Features

Improved parsing

• Command substitution: $() for command substitution
• Non-interactive mode: -c option to run commands directly
• Herestring: <<< for direct string input
• Heredoc expansion: Variables and commands inside heredoc and herestring
• Quote handling: Advanced single and double quote processing
• Character escaping: Support for \ (backslash)
• Unclosed tokens: Displays PS2 for line continuation

Variables and expansion

• Shell variables: Local variables in addition to environment variables
• Special variables:
  • $$ - Shell PID
  • $RANDOM - Random number
  • $TIME - Current timestamp
  • $_ - Last argument of the previous command
  • $? - Last exit code
• Tilde expansion: ~ expands to the home directory
• Wildcard expansion: *, ?, and [a-z] with advanced patterns

Logical operators and control

• Logical operators: && and || with parenthesis support for precedence
• Subshells: () for execution in subprocesses
• Concurrent execution: Handling of multiple processes

Builtin commands

All builtins include --help and --version:

• echo - With -n and -e options
• cd - With cd - support (previous directory)
• pwd - Current directory
• export - Environment variable management
• unset - Remove variables
• env - With -s to show shell variables
• exit - Exit the shell
• history - Command history management
• help - Built-in help system
• banner - Welcome message

🔧 Installation

git clone git@github.com:Kobayashi82/Minishell.git
cd minishell
make

🖥️ Usage

Interactive mode

# Start minishell
./minishell

# Basic example
minishell$ echo "Hello World"
Hello World

Non-interactive mode (-c option)

# Run commands directly
./minishell -c "echo 'Hello from the command line'"
./minishell -c "ls -la | grep '.c' | wc -l"
./minishell -c "export VAR=value && echo \$VAR"

# Complex commands with pipes and redirection
./minishell -c "cat /etc/passwd | grep root > users.txt"

Usage examples

# Pipe usage
minishell$ ls -la | grep ".c" | wc -l

# Redirection
minishell$ echo "content" > file.txt
minishell$ cat < file.txt

# Variables
minishell$ export VAR="value"
minishell$ echo $VAR

# Heredoc
minishell$ cat << EOF
> line 1
> line 2
> EOF

📚 Advanced examples

Command substitution

minishell$ echo "Current date: $(date)"
Current date: Mon 26 May 2025 10:30:15 CEST

minishell$ files=$(ls *.c)
minishell$ echo $files

Logical operators

minishell$ make && echo "Build succeeded" || echo "Build failed"

minishell$ (cd /tmp && pwd) && pwd
/tmp
/original/path

Wildcards

minishell$ ls *.c           # .c files
minishell$ ls file?.txt     # file1.txt, file2.txt, etc.
minishell$ ls [a-z]*.c      # .c files starting with lowercase

Herestring

minishell$ cat <<< "This is a line of text"
This is a line of text

minishell$ bc <<< "2+2"
4

🧪 Technical Highlights

Memory management

• ✅ No memory leaks: Full heap cleanup
• ✅ No open file descriptors: Properly closes all FDs
• ✅ Signal handling: Robust handling of SIGINT, SIGQUIT, EOF

Bash compatibility

• ✅ Identical error handling: Error codes and messages like Bash
• ✅ Signal behavior: Ctrl-C, Ctrl-D, Ctrl-\ like Bash
• ✅ Special variables: Identical behavior to Bash

Robust parsing

• ✅ Recursive parser: Complete syntax parsing
• ✅ Error handling: Detailed error detection and reporting
• ✅ Advanced tokenization: Support for complex tokens

📄 License

This project is licensed under the WTFPL – Do What the Fuck You Want to Public License.

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🐚 Developed as part of the 42 School curriculum 🐚

"In Minishell, the last feature is never really the last"