> ## Documentation Index > Fetch the complete documentation index at: https://aspect.build/llms.txt > Use this file to discover all available pages before exploring further. # Process `function` **Process.command** 
        
          def Process.command(
          program: str,
          /
          ) -> std.process.Command
`function` **Process.exit** 
        
          def Process.exit(
          code: int,
          /,
          message: None | str = None
          ) -> typing.Never
End the task with exit `code` (0..=255, no default, as in Rust's `std::process::exit`) and, optionally, a `message`, with no traceback. The message prints as an `ERROR:` line for a non-zero code and `INFO:` for 0. Use it for an expected refusal, or an early "nothing to do", from however deep in the call stack it is discovered; keep `fail()` for bugs, where the traceback helps. `ASPECT_DEBUG=1` prints the traceback after the message anyway. The exit unwinds through every caller like an error: `ctx.defer` callbacks still run, but whatever the task body had yet to run does not, including a status surface's final update. A task that reports to a surface ends through its final `phases.update` instead. `function` **Process.id** 
        
          def Process.id() -> int
Return the current (aspect-cli) process's ID. Stable for the lifetime of this AXL evaluator and unique within the host OS at any given moment, so it's a useful per-task identifier for state files under the shared job tmpdir: each task invocation gets its own aspect-cli process and therefore its own id. Available from any ctx flavor (FeatureContext / TaskContext) — `ctx.std` is on both, and `id()` doesn't depend on a task being in scope. `function` **Process.which** 
        
          def Process.which(
          name: str,
          /
          ) -> None | str
The absolute path `command(name)` would run, or `None` when no `PATH` entry holds an executable of that name — `which` / `command -v`. A bare name is looked up along `PATH`; a name containing a path separator is checked as given. On Unix the file must carry an execute bit; on Windows the `PATHEXT` extensions are tried. **Examples** ```python theme={null} helper = "aspect" if ctx.std.process.which("aspect") else ctx.std.env.current_exe() ``` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.