About

Minishell is a UNIX-like shell implemented in C, aiming to provide a basic replica of a bash-like shell. It supports a variety of features including command execution, I/O redirection, pipelines, variable expansion, command history, tab completion, signal handling, and exit status handling. Find a detailed list of requirements for this project here: subject.pdf.

Usage

git clone this project cd into it and make. the program is executed as so:

./minishell

The program will then prompt you for input. It is used exactly as a bash shell as such:

ls -l
echo "Hello world"
cat file.txt

Key features

• Command execution
• I/O redirection
• Pipelines
• Variable expension
• Command history
• Tab completion
• Signal handling
• exit status handling

Implementation

The program uses the readline library to prompt input to the user and can be divided into four main parts.

1. Lexer (Tokenizer):

• The lexer tokenizes the input command line string into individual tokens using get_token() function.
• It skips over leading spaces and identifies various types of tokens, including commands, arguments, and redirection operators.
• Special characters like quotes are handled to ensure correct tokenization.

2. Expander:

• The expander is responsible for expanding variables in the command line.
• It identifies variables prefixed with $ and replaces them with their corresponding values.
• Special variables like $? for exit status are supported.

3. AST (Abstract Syntax Tree) Generator:

• The AST generator constructs a tree structure representing the syntax of the command line input.
• It parses commands, arguments, and redirections and organizes them into a hierarchical tree.
• Commands separated by pipes (|) are connected as nodes in the tree.

4. Executor:

• The executor executes the commands represented by the AST.
• It matches commands with built-in functions or external executables and executes them accordingly.
• I/O redirection, command execution in child processes, and handling of exit statuses are managed within the executor.

Testing

cd into the test/ directory and run ./tester. The tester was developed by Lucas Kuhn (minishell tester) and was really usefull to rigouresly test for errors. Tests can be added in the "test/extras" file to cover more aspects of the shell.

Norme

All 42 projects must be written following the Norme.

- No for, do while, switch, case or goto are allowed
- No more than 25 lines per function and 5 functions per file
- No assigns and declarations in the same line (unless static)
- Each line must be at most 80 columns wide, comments included
- A function can take 4 named parameters maximum
- No more than 5 variables in 1 function