[Caml-list] Unix.create_process

[Caml-list] Unix.create_process

[Rolf Wester]

Hi,

I want to start a process and read the stdout channel of this process.
I tried:

let instring = String.create 10 in
    let pid = Unix.create_process ~prog:"ls" ~args:[|"/usr"|] 
			~stdin:Unix.stdin ~stdout:Unix.stdin ~stderr:Unix.stderr in
    let nread = Unix.read Unix.stdin ~buf:instring ~pos:0 ~len:10 in instring;;

but this one waits for keyboeard input instead of reading the output of ls.
When I type  ~stdout:Unix.stdout instead of  ~stdout:Unix.stdin the ls 
output is written to stdout (as expected).

Can anybody tell me what I made wrong?

Thanks in advance.

Rofl Wester 

-------------------------------------
Rolf Wester
rolf.wester@ilt.fraunhofer.de
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Re: [Caml-list] Unix.create_process

[Francois Pottier]

Hi Rolf,

You need to create a pipe, have the process write into one end of it, and read
data off the other end. The function [Unix.open_process_in] does that for
you. Here is an example:

  let one_liner command =
    let channel = Unix.open_process_in command in
    let line = input_line channel in
    let _ = Unix.close_process_in channel in
    line
  ;;

-- 
François Pottier
Francois.Pottier@inria.fr
http://pauillac.inria.fr/~fpottier/
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