42sh 🐧

42sh, an Epitech project, the challenge is to recreate a terminal environment similar to tcsh, with a command prompt and features, offering practical experience in shell programming.

How to run

make
./42sh

How to run Unit Tests

make
make test

if you want display unit tests:

cat tests/test

Available Features

Feature	Description
Bash Command Execution	Execution of Bash commands within the shell environment
Built-in Commands	Implementation of built-in shell commands
Redirection	Input/output redirection using > and >> for writing to and appending to files, and < and << for reading from files
Pipelines	Ability to chain commands using the pipe operator |
Command Sequencing	Sequential execution of commands separated by ;
Inhibitors	Usage of inhibitors to control command execution (\, ", ')
Globbing	Pattern matching for file names using *, ?, and []
Logical Operators	Support for logical operators && (AND) and || (OR) for command execution control
Local and Environment Variables	Management of local and environment variables
History	Tracking and access to command history
Alias	Creation and use of command aliases for convenience
Line Edition	Line editing capabilities for command input using arrow keys and editing shortcuts
Auto-Completion	Automatic suggestion of commands and file names during command input

Available Builtins

Builtin	Description
cd	Change the current directory
env	Display or modify the environment variables
unsetenv	Unset one or more environment variables
exit	Exit the shell with an optional exit status
alias	Create or display aliases for commands
unalias	Remove aliases for commands
set	Set or unset shell options and positional parameters
unset	Unset values and attributes of shell variables and functions
history	Display command history or manipulate it
which	Display the full path of shell commands
where	Display all locations of a given executable
repeat	Repeat a command a specified number of times

Implementation Details

Lexer and Parser

The system we used in our 42sh relies on a lexer and a parser to analyze the user input and understand its structure. Here is an overview of how it works:

• Lexer: The lexer processes the user input by breaking it down into a token, which represents several parts of the command, for example, it identifies keywords such as builtins or separators such as ;

• Parser: The parser takes these tokens as input and interprets them against well-defined rules to be able to execute them in the right way

Token Usage

We use tokens in our implementation to represent different elements of user input. Examples include:

• Command Tokens: Represent the main command and its arguments.
• Operator Tokens: Represent operators such as redirection (>, <) and pipes (|).

Example Usage

To show you how the parser lexer works here is an example :

1. COMMAND: ls
2. ARGUMENT: -l
3. PIPE: |
4. COMMAND: grep
5. ARGUMENT: "example"

The parser will use these tokens to be able to apply shell rules and execute them.

Acknowledgements

We would like to thank all the team members for their hard work and determination, thank you for everything:

• Nicolas Dumetz
• Maximilien Dheripre
• Matisse Dufour
• Charles Ignoux
• Charles Faudou

Contact

For any questions, suggestions, or feedback, feel free to contact us.