Minishell

A simple shell implementation in C that mimics the behavior of bash, created as part of the 42 School curriculum.

Table of Contents

• Overview
• Features
• Requirements
• Installation
• Usage
• Built-in Commands
• Error Handling
• Project Structure
• Testing
• Authors
• License

Overview

Minishell is a simplified version of a Unix shell that provides basic command-line functionality. This project demonstrates understanding of process management, file descriptors, signal handling, and parsing in C.

Screenshots

Example of minishell running basic commands

Features

Mandatory Features

• Prompt Display: Shows a prompt when waiting for new commands
• Command History: Working history of executed commands
• Executable Search: Finds and launches executables based on PATH variable or relative/absolute paths
• Global Variables: Minimal use of global variables (only for signal handling)
• Quote Handling:
  • Single quotes (') prevent interpretation of meta-characters
  • Double quotes (") prevent interpretation except for $
• Redirections:
  • < redirects input
  • > redirects output
  • << heredoc (reads input until delimiter)
  • >> redirects output in append mode
• Pipes: | character pipes output of each command to input of next command
• Environment Variables: $ followed by variable name expands to variable value
• Exit Status: $? expands to exit status of most recently executed foreground pipeline
• Signal Handling:
  • ctrl-C displays new prompt on new line
  • ctrl-D exits the shell
  • ctrl-\ does nothing

Built-in Commands

• echo with option -n
• cd with only relative or absolute path
• pwd with no options
• export with no options
• unset with no options
• env with no options or arguments
• exit with no options

Requirements

• Language: C
• Compiler: gcc with flags -Wall -Wextra -Werror
• External Libraries:
  • readline (for command-line editing and history)
  • Standard C library functions
• System: Unix-like operating system (Linux, macOS)

Installation

1. Clone the repository:

git clone <repository-url>
cd minishell

2. Compile the project:

make

3. Run the executable:

./minishell

Usage

Basic Commands

$ ls -la
$ echo "Hello World"
$ pwd
$ cd /path/to/directory

Redirections

$ echo "Hello" > file.txt
$ cat < file.txt
$ echo "World" >> file.txt
$ cat << EOF
heredoc content
EOF

Pipes

$ ls -la | grep "txt"
$ cat file.txt | wc -l

Environment Variables

$ echo $HOME
$ echo $USER
$ export MY_VAR="value"
$ echo $MY_VAR

Exit Status

$ ls non_existent_file
$ echo $?

Built-in Commands

echo

Displays a line of text.

$ echo "Hello World"
$ echo -n "No newline"

cd

Changes the current directory.

$ cd /path/to/directory
$ cd ..
$ cd ~

pwd

Prints the current working directory.

$ pwd

export

Sets environment variables.

$ export VAR="value"

unset

Removes environment variables.

$ unset VAR

env

Displays environment variables.

$ env

exit

Exits the shell.

$ exit
$ exit 42

Error Handling

The shell handles various error conditions gracefully:

• Command not found: Displays appropriate error message
• Permission denied: Shows permission error for non-executable files
• Invalid redirections: Handles file access errors
• Syntax errors: Reports parsing errors for invalid command syntax
• Memory allocation: Proper cleanup on memory allocation failures

Project Structure

minishell/
├── src/
│   ├── main.c
│   ├── parser/
│   ├── executor/
│   ├── builtins/
│   ├── signals/
│   └── utils/
├── includes/
│   └── minishell.h
├── libft/
├── Makefile
├── screenshot.png
└── README.md

Testing

Basic Functionality

• Test all built-in commands
• Verify pipe functionality with multiple commands
• Test all redirection types
• Check quote handling (single and double)
• Verify environment variable expansion

Edge Cases

• Empty commands
• Multiple consecutive spaces/tabs
• Unclosed quotes
• Invalid redirections
• Signal handling during command execution

Memory Management

• Run with valgrind to check for memory leaks
• Test extensive command sequences
• Verify proper cleanup on exit

Demo

The screenshot above shows minishell in action, demonstrating various features including command execution, built-in commands, and proper prompt display.

Authors

• mtarza13
• yasserbarhdadi

License

This project is part of the 42 School curriculum and is subject to the school's academic policies.

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Note: This implementation focuses on the mandatory requirements of the minishell project. Advanced features like logical operators (&&, ||), wildcards, or advanced job control are not included in this version.