0-shell/
├── src/
│   ├── main.rs             // Entry point
│   ├── shell.rs            // Shell loop, prompt, and input handling
│   ├── parser.rs           // Command parsing logic
│   ├── commands/
│   │   ├── mod.rs
│   │   ├── echo.rs
│   │   ├── cd.rs
│   │   ├── ls.rs
│   │   ├── pwd.rs
│   │   ├── cat.rs
│   │   ├── cp.rs
│   │   ├── rm.rs
│   │   ├── mv.rs
│   │   ├── mkdir.rs
│   │   └── exit.rs
├── tests/
│   └── integration.rs      // Integration and command tests
├── Cargo.toml              // Rust project configuration
├── README.md               // Documentation
└── .gitignore

► REPL Loop

• Implement $ prompt display
• Read user input with stdin
• Trim whitespace & ignore empty input
• Handle Ctrl+D → detect EOF and exit gracefully
• Split input into tokens (naive split by whitespace)
• Handle quoted arguments (basic " " parsing)

► Dispatcher

• Create a command map (HashMap<&str, fn(Vec<String>))
• Implement unknown command handler → "Command '<name>' not found"
• Connect REPL loop with dispatcher

► Simple Built-ins

• Implement exit → exit with code 0
• Implement echo → print args joined with spaces
• Implement pwd → print std::env::current_dir

► cd

• Implement basic cd <path>
• Support cd with no args → go to $HOME
• Handle invalid paths (error message)
• Update prompt after cd (if bonus feature enabled)

► ls

• Implement basic ls (list current directory)
• Add ls <path> support
• Implement -a: include hidden files
• Implement -F: mark dirs with /, executables with *
• Implement -l:
  • Show permissions string (drwxr-xr-x)
  • Show ownership (user/group)
  • Show file size
  • Show modified timestamp

► cat

• Implement reading a single file → print to stdout
• Support multiple files → concatenate output
• Handle non-existent file → error message
• Handle permission denied → error message

► cp

• Implement copying file contents (read + write)
• Preserve file permissions
• Handle overwrite (default overwrite)
• Handle invalid source/target

► mv

• Implement move with std::fs::rename
• If rename fails, fallback to copy + remove
• Handle invalid args gracefully

► mkdir

• Implement mkdir <dir>
• Implement -p (recursive create)
• Handle already exists error

► rm

• Implement removing a single file
• Handle removing non-existent file (error)
• Implement -r recursive delete
• Protect against accidental delete of . or ..

► Error Handling Framework

• Define ShellError enum
• Create helper for standardized error messages
• Wrap filesystem calls with error-safe functions
• Ensure all commands use consistent error output

Follow the official installation guide:
https://www.rust-lang.org/tools/install

Or run:

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

Then restart your terminal and verify with:

rustc --version

cargo build --release
./target/release/0-shell

You will see the shell prompt:

0-shell$