Shell-Go

A simple shell implementation in Go (not golang btw).

Overview

Shell-Go is an interactive command-line shell written in Go that provides a REPL (Read-Eval-Print Loop) interface with various builtin commands for file system operations, I/O, system management, and network utilities.

Features

• Interactive REPL: Command-line interface with custom prompt showing current directory
• Signal Handling: Graceful handling of SIGINT and SIGTERM signals
• Custom Prompt: Path formatting that displays home directory as ~
• Environment Variable Management: Built-in support for setting and viewing environment variables
• Modular Command Architecture: Commands organized by category (filesystem, I/O, network, system)
• Flag Support: Many commands support flags using the cobra library

Requirements

• Go 1.23.2 or later
• Optional: just for build automation (or use go commands directly)

Installation & Building

Using Just

# Build the binary
just build

# Run directly
just run

The build process creates a binary named shell-go in the current directory.

Usage

Start the shell by running the binary:

./shell-go

Type commands and press Enter to execute them. To exit the shell, use the exit command or press Ctrl+C (handled gracefully via signal handling).

Available Commands

File System Commands

• cat [file] - Read and display file contents

  • -n, --number - Number the output lines, starting at 1
  • -e - Display non-printing characters and a dollar sign ($) at the end of each line

• cd [directory] - Change directory

  • Supports ~ as shorthand for home directory
  • Supports both absolute and relative paths

• ls - List files and directories

  • -a, --all - View all files and directories (including hidden files)
  • -d, --dirs - View only directories
  • -f, --files - View only files

• mkdir [directory] - Create a new directory

• pwd - Print the current working directory

• rm [file] - Remove a file

  • -R, -r - Attempt to remove the file hierarchy rooted in each file argument (recursive)

• rmdir [directory] - Remove an empty directory

• touch [file] - Create an empty file or update file timestamp

• ln [target] [link] or link [target] [link] - Create a symbolic link

I/O Commands

• clear - Clear the terminal screen

• echo [text] - Print text to standard output

System Commands

• exit - Exit the shell gracefully

• export [key]=[value] - Set an environment variable

  • Example: export PATH=/usr/bin

• env - Print all environment variables

• hostname - Print the name of the current host system

• whoami - Print the current username

Network Commands

• nslookup [domain] - Perform DNS lookup for a domain name
  • Displays DNS server information and resolved IP addresses

Project Structure

shell-go/
├── cmd/
│   └── main.go          # Main entry point with REPL loop
├── internal/
│   └── shell/
│       ├── exit/         # Exit functionality
│       ├── prompt/       # Prompt formatting (home directory as ~)
│       └── signals/      # Signal handling (SIGINT, SIGTERM)
├── pkg/
│   └── builtins/
│       ├── fs/           # File system commands
│       │   ├── cat.go
│       │   ├── cd.go
│       │   ├── link.go
│       │   ├── ls.go
│       │   ├── mkdir.go
│       │   ├── pwd.go
│       │   ├── rm.go
│       │   ├── rmdir.go
│       │   └── touch.go
│       ├── io/           # I/O commands
│       │   ├── clear.go
│       │   └── echo.go
│       ├── network/      # Network commands
│       │   └── nslookup.go
│       └── system/       # System commands
│           ├── env.go
│           ├── exit.go
│           ├── export.go
│           ├── hostname.go
│           └── whoami.go
├── go.mod
├── justfile
└── README.md

Development Notes

• The shell uses environment variables (specifically PWD) for state management
• Signal handling runs in a separate goroutine to allow graceful shutdown
• Many commands use the cobra library for flag parsing and command structure
• The prompt formatter automatically converts absolute paths starting with $HOME to use ~ notation
• Unknown commands display "Unknown command" and continue the REPL loop