Re: [Caml-list] process conundrum

[Nicolas FRANCOIS (AKA El Bofo) <nicolas.francois@free.fr>]

On 13 Feb 2002 13:43:14 -0800
David Fox <david@lindows.com> wrote:

> Suppose I open a process to reverse the lines of a file like so:
> 
> # let readable, writable = 
>   Unix.open_process "cat -n | sort -n -r | sed 's:^[ 0-9]*[^ 0-9]::'";;
> 
> Then I write a few lines to it:
> 
> # output_string writable "a\n";;
> # output_string writable "b\n";;
> # output_string writable "c\n";;
> 
> Now I close the write end to cause an EOF, so the output arrives on
> readable:
> 
> # close_out writable;;
> # input_line readable;;
> - : string = "c"
> # input_line readable;;
> - : string = "b"
> # input_line readable;;
> - : string = "a"
> # input_line readable;;
> Exception: End_of_file.

This can be avoided with a

try ... with End_of_file -> ...
 
> How do I cleanly terminate the process?
> 
> # Unix.close_process (readable, writable);;
> Exception: Sys_error "Bad file descriptor".

I tried your example and only got a 

# Unix.close_process (readable, writable);;
- : Unix.process_status = WEXITED 0

So what's the problem ?

\bye

-- 

                   Nicolas FRANCOIS
            http://nicolas.francois.free.fr
 A TRUE Klingon programmer does NOT comment his code
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