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Build your own Shell

Learn about parsing shell commands, executing programs and more

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Build your own Shell

Build your own Shell is free this October.

The core challenge experience is completely free this month. If you'd like to enjoy advanced features such as running turbo tests, dark mode, or unlimited code examples, you'll need a membership.

Start free challenge → View Membership Plans →

A shell is the program that interprets what you type into the terminal. It reads your commands, runs programs, and prints their output. Popular examples are Bash and ZSH.

In this challenge, you'll build your own shell from scratch.

Your shell will run a REPL, parse commands, spawn processes, and more.

What exactly will I build?

What exactly will I learn?

Why should I build such a project?

What are the pre-requisites for this challenge?

Stages

Handle invalid commands

Implement a REPL

Locate executable files

Navigation

The pwd builtin

The cd builtin: Absolute paths

The cd builtin: Relative paths

The cd builtin: Home directory

Quoting

Backslash outside quotes

Backslash within single quotes

Backslash within double quotes

Executing a quoted executable

Redirection

Redirect stdout

Redirect stderr

Autocompletion

Builtin completion

Completion with arguments

Missing completions

Executable completion

Multiple completions

Partial completions

Pipelines

Dual-command pipeline

Pipelines with built-ins

Multi-command pipelines

History

The history builtin

Listing history

Limiting history entries

Up-arrow navigation

Down-arrow navigation

Executing commands from history

History Persistence

Read history from file

Write history to file

Append history to file

Read history on startup

Write history on exit

Append history on exit

RECENT ATTEMPTS 0

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