Minishell

Description

Minishell is a simple, custom shell written in C, designed to emulate the functionality of the bash shell. The project involves handling various processes, file descriptors, and command-line inputs, giving me an opportunity to delve into key concepts related to system programming.

This shell includes support for a command-line interface, pipes, redirections, environment variable handling, and a few built-in commands.

Features

• Displays a command prompt waiting for user input.
• Handles both relative and absolute paths for commands.
• Command history is maintained for easier navigation.
• Supports pipes (|) for passing the output of one command as input to another.
• Redirections:
  • < for input redirection.
  • > for output redirection.
  • << reads input until a delimiter is found (here-doc).
  • >> appends output to an existing file.
• Handles environment variables ($) and expands them accordingly.
• Recognizes and expands $? to the exit status of the most recent command.
• Supports signal handling for ctrl-C, ctrl-D, and ctrl-\, behaving similarly to bash.
• Built-in commands:
  • echo (with -n option)
  • cd (with relative or absolute paths)
  • pwd
  • export
  • unset
  • env
  • exit

Bonus Features

• Logical operators && and || with support for prioritizing execution using parentheses.
• Wildcard * support for pattern matching in the current directory.

Installation

1. Clone the repository:

   git clone git@github.com:Rui-Pedro-Pires/Minishell.git

2. Navigate to the project directory:

   cd Minishell

3. Compile the project using the provided Makefile:

   make

Usage

To start the shell:

./minishell

Once inside the shell, you can execute commands just like in a regular bash terminal.

Example commands:

echo "Hello, World!"
ls -la | grep minishell
cat < input.txt > output.txt
export PATH=/usr/local/bin

Requirements

• C programming language.
• The readline library for command history.

External Functions Used

The shell makes use of the following external functions:

• readline, rl_clear_history, rl_on_new_line, rl_replace_line, rl_redisplay, add_history
• Standard system functions like printf, malloc, free, write, fork, wait, execve, dup, pipe, and more.