14

Challenge 14 - Write Your Own Shell

This challenge corresponds to the fourteenth part of the Coding Challenges series by John Crickett https://codingchallenges.fyi/challenges/challenge-shell.

Description

As the name suggests, here we try to build a simple shell using the child_process module of Node.js. The shell supports all the commands (including piped commands) that are available in any standard LINUX shell.

Apart from the builtin commands - cd, pwd, exit, history are executed by spawning a new process and passing all the relevant arguments provided by the user.

Usage

You can use ts-node to run the tool as follows:

npx ts-node shell.ts

All the executed commands are stored in a file in the home directory of the user with the name .ccsh_history. You can then use the history command to see the previously executed commands.

To exit the shell, use the exit command.

The pwd and cd command support is implemented using the inbuilt cwd() and chdir() function exposed by the process module.

Run tests

To run the tests for the shell tool, go to the root directory of this repository and run the following command:

npm test src/14/

All the tests are made for LINUX environment only. If you want to run the tests in Windows environment, you can use the Git Bash terminal or Windows Subsystem for Linux (WSL).

Note: While testing for pwd command, the LINUX environment follows the convention of printing the path without a trailing slash. However, the Windows environment prints the path with a trailing slash. So, the tests for pwd will fail in Windows environment. This is an expected behavior and the tests should pass in LINUX environment.