Libuv: uv.spawn() Options, stdio Configuration, Process Exit, and Process Management Functions

19th chunk of `runtime/doc/luvref.txt`

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 already provided via `path`. On
                    Windows, this uses CreateProcess which concatenates the
                    arguments into a string. This can cause some strange
                    errors (see `options.verbatim` below for Windows).
                  - `options.stdio` - Set the file descriptors that will be
                    made available to the child process. The convention is
                    that the first entries are stdin, stdout, and stderr.
                    (Note: On Windows, file descriptors after the third are
                    available to the child process only if the child processes
                    uses the MSVCRT runtime.)
                  - `options.env` - Set environment variables for the new
                    process.
                  - `options.cwd` - Set the current working directory for the
                    sub-process.
                  - `options.uid` - Set the child process' user id.
                  - `options.gid` - Set the child process' group id.
                  - `options.verbatim` - If true, do not wrap any arguments in
                    quotes, or perform any other escaping, when converting the
                    argument list into a command line string. This option is
                    only meaningful on Windows systems. On Unix it is silently
                    ignored.
                  - `options.detached` - If true, spawn the child process in a
                    detached state - this will make it a process group leader,
                    and will effectively enable the child to keep running
                    after the parent exits. Note that the child process will
                    still keep the parent's event loop alive unless the parent
                    process calls |uv.unref()| on the child's process handle.
                  - `options.hide` - If true, hide the subprocess console
                    window that would normally be created. This option is only
                    meaningful on Windows systems. On Unix it is silently
                    ignored.

                The `options.stdio` entries can take many shapes.

                  - If they are numbers, then the child process inherits that
                    same zero-indexed fd from the parent process.
                  - If |uv_stream_t| handles are passed in, those are used as
                    a read-write pipe or inherited stream depending if the
                    stream has a valid fd.
                  - Including `nil` placeholders means to ignore that fd in
                    the child process.

                When the child process exits, `on_exit` is called with an exit
                code and signal.

                Returns: `uv_process_t userdata`, `integer`

uv.process_kill({process}, {signame})                         *uv.process_kill()*

                > method form `process:kill(signame)`

                Parameters:
                - `process`: `uv_process_t userdata`
                - `signame`: `string` or `integer` or `nil` (default: `sigterm`)

                Sends the specified signal to the given process handle. Check
                the documentation on |uv_signal_t| for signal support,
                specially on Windows.

                See |luv-constants| for supported `signame` input and output
                values.

                Returns: `0` or `fail`

uv.kill({pid}, {signame})                                             *uv.kill()*

                Parameters:
                - `pid`: `integer`
                - `signame`: `string` or `integer` or `nil` (default: `sigterm`)

                Sends the specified signal to the given PID. Check the
                documentation on |uv_signal_t| for signal support, specially
                on Windows.

                See |luv-constants| for supported `signame` input and output
                values.

                Returns: `0` or `fail`

uv.process_get_pid({process})

Title: Libuv: uv.spawn() Options, stdio Configuration, Process Exit, and Process Management Functions

Summary

This section details the `options.stdio` configurations for the `uv.spawn()` function, explaining how file descriptors are inherited or piped between parent and child processes. It also describes the exit callback `on_exit`, triggered when the child process terminates, providing the exit code and signal. It further defines `uv.process_kill()` and `uv.kill()` functions, used to send signals to a process either by its handle or process ID (PID) respectively, referencing the |uv_signal_t| documentation for signal support, especially on Windows.