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⌨️ Command line shell (executable) ​

The command-line shell executable provides text command dispatch for both interactive terminal sessions and one-shot command invocation.

Role ​

  • Parses user input into built-in command handlers or executable launch requests.
  • Maintains shell process state (current_directory, user, host, running flag).

Startup and lifecycle ​

  1. Initializes Shell state with current task and root directory.
  2. Resolves User from task env; if absent, runs interactive authentication flow.
  3. Loads Paths and Host environment variables.
  4. Runs interactive loop (prompt + read + parse) when no args; otherwise executes one command from args.

Runtime integration points ​

  • task module for environment variable reads/writes (User, Paths, Current_directory, Host).
  • authentication crate for login fallback flow.
  • virtual_file_system for path resolution and command file discovery.
  • xila::executable::execute for non-built-in command execution.

Data and control flow / VFS touchpoints ​

  • Built-in command path: command token -> command module handler -> direct side effects.
  • External executable path:
    1. resolve command name using configured Paths directories,
    2. set Current_directory env,
    3. call execute(...),
    4. join spawned task.
  • VFS touchpoints include directory traversal during command resolution and file operations in command modules.

Concurrency and event-loop model ​

  • Primary model is single interactive loop over standard input.
  • External commands run as separate executable tasks and are synchronously joined by shell.

Failure semantics ​

  • Command-level errors are written to standard_error and loop continues.
  • Argument option misuse maps through getargs to typed shell errors.
  • Missing environment variables (Paths, Host) are fatal for startup path.

Contract vs implementation ​

  • Contract: text shell that supports built-ins and executable dispatch from search paths.
  • Current implementation: explicit match-based built-in table (exit, cd, ls, mkdir, dns_resolve, ping, ip, etc.) with fallback resolver-based execution.

Operational limitations ​

  • Tokenization currently relies on simple space splitting in interactive path (no full quoting/escaping grammar).
  • Prompt/loop behavior is line-oriented and depends on standard input device semantics.

References ​