Creating a simple Shell 🐚

• Creating a simple Shell 🐚
  • Usage
  • Compatibility
  • Grammar
  • Architecture
  • Work Flow
  • Works
    • Builtins
    • Expands
    • Signals
    • Parser
    • Excution
    • Bonus
    • Error

This project is about creating a simple shell by simple rules

Minishell is a project to creating a lightweight shell capable of parsing and executing simple commands, pipe line, redirections from a single line input.

It features custom-built built-in commands(cd, echo ...), handles environment variables, maintains command history, and effectively manages signals and errors.

This minishell is based on bash

Yeah, we make own little bash

Usage

We do not handle unclosed quotes!

If a quote remains unclosed and leaves an odd number of quotes, the remaining quote is interpreted as a single character!

Please be mindful of this when using

Compatibility

The program is compiled by clang 12 with Mac OS
You can use our makefile for compile, but it requires GNU's readline library!

enjoy our shell

Grammar

↗️ grammar.md

Architecture

flowchart LR
    A[Lexer]-->B[Tokenizer]-->C[Parser]-->D[Expands]-->E[Excute]
    E-.->Z[Builtins]
    E-.->X[Commands]

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Work Flow

gantt
dateFormat YYYY-MM-DD
title minishell

section jeongwpa
	Builtins : done, des1, after sideline1, 14d
	Expand : done, des2, after des1, 7d
	Signals : done, des3, after des2, 2d
	bonus( * ) : done, des4, after des3, 14d

section jiwojung
	parser : done, des5, after sideline1, 21d
	excution : done, des6, after des5, 14d
	bonus( &&, ||, () ) : done, des7, after des6, 5d

section sideline
	understanding functions : done, sideline1, 2024-02-19, 1d
	grammar summary : done, sideline2, 2024-02-22, 2d
	code review, refactoring : after des4, 7d
	final test, fix bugs : crit, 2024-04-04, 11d

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Works

Builtins

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

Expands

• Handle environment variables ($ followed by a sequence of characters) which should expand to their values

Signals

• ctrl - C displays a new prompt on a new line
• ctrl - D exits the shell
• ctrl - \ does nothing

also it works differently with cat

Parser

• Lexer & Tokenizer includes
• Create own AST
• Create it with reference to grammar

Excution

• Implement redirections (<, >, <<, >>)
• Implement pipes (| character)

Bonus

• Implement &&, ||, parenthesis for priorities
  • ↗️ example
• Implement wildcards *

Error

• Handling exit status, error messages