documentation patch for process

[Simon Marlow]

My apologies, I missed this:

On 08/02/2012 21:25, Evan Laforge wrote:

> % git diff HEAD\^
> diff --git a/System/Process.hs b/System/Process.hs
> index f3a8f9b..a372228 100644
> --- a/System/Process.hs
> +++ b/System/Process.hs
> @@ -234,9 +234,18 @@ To create a pipe from which to read the output of @ls@:
>   To also set the directory in which to run @ls@:
>
>   >    (_, Just hout, _, _)<-
> ->        createProcess (proc "ls" []){ cwd = Just "\home\bob",
> +>        createProcess (proc "ls" []){ cwd = Just "/home/bob",
>   >                                      std_out = CreatePipe }
>
> +Note that this does /not/ throw an error if the binary is not found,
> +or not executable.  Instead, the process will fail with the exit code 127.
> +But you can't rely on it failing quickly, because it may e.g. hang up
> +searching the PATH on a slow NFS mount.  Since there's no way to tell when
> +the exec() has succeeded, the only way to reliably know if the createProcess
> +failed is to 'waitForProcess'.
> +
> +If the CreateProcess record's 'cwd' directory doesn't exist, the exit code
> +will be 126.
>   -}

This isn't true on Windows, so at least the comment should be qualified 
to that effect.

>   createProcess
>     :: CreateProcess
> diff --git a/System/Process/Internals.hs b/System/Process/Internals.hs
> index 11de1f4..2a6c047 100644
> --- a/System/Process/Internals.hs
> +++ b/System/Process/Internals.hs
> @@ -199,7 +199,8 @@ data CmdSpec
>     = ShellCommand String
>         -- ^ a command line to execute using the shell
>     | RawCommand FilePath [String]
> -      -- ^ the filename of an executable with a list of arguments
> +      -- ^ The filename of an executable with a list of arguments.
> +      -- The PATH is searched for the executable.

Again, I think Windows has a rather more complex method for finding 
binaries, and in all cases it makes a difference whether the FilePath is 
absolute or not.  I forget the precise details.

The best way forward with this is to fix up the patch and submit it as a 
GHC ticket.

Cheers,
	Simon