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From: "Beck01, Wolfgang" <BeckW@t-systems.com>
To: caml-list@inria.fr
Subject: [Caml-list] different behaviour of Unix.fork on FreeBSD and Linux
Date: Mon, 19 May 2003 11:35:59 +0200
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X-Spam: no; 0.00; t-systems:01 fork:01 printf:01 3.02:01 3.06:01 ocaml:01 behaviour:01 father:97 unix:02 wolfgang:02 let:04 beck:04 output:05 recompiling:06 loop:06 
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Hello,

while recompiling an OCaml program developed under FrreeBSD
in Linux, I had some problems. 

What is the output of the following OCaml program?

open Printf
open Unix

let ftst() =
    let pid = fork()
    in
    if pid = 0 then
	printf "son\n"
    else begin
	printf "father\n";
	let _= wait()
	in
	()
    end
    
let aa =
    printf "test\n"

let main() =
printf "main\n";
    ftst()
;;

main()

On FreeBSD (OCaml 3.02), it is what I expected
  test
  main
  father
  son

However, on Linux (OCaml 3.06), it is

  test
  main
  son
  test    <-- why?
  main    <-- why?
  father

It looks as if the fork causes a second program initialization.
Strange that this doesn't result in an endless loop.

Any ideas?


--
Wolfgang Beck
T-Systems Nova GmbH 

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