Re: Redirecting STDOUT/STDERR of a process forked by a thread

Okay, I just figured out how to do it.
I did this in the forked child: 
$fh = new FileHandle();
$fh->fdopen(1, 'w');
<now use this $fh for redirection>

(If anybody has similar problem and would like to know
the solution in detail, I'll post the details).

Sreeji

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<[email protected]> wrote: > Hi,
> 
> I'm trying to use threads in one of our
> applications. The application has
> few long running jobs which can be done in parallel
> and I'm thinking
> perl-ithreads can be of use here. 
> My proto-type implementation does something like
> this:
> 
> 1. Open Log main.log
> 2. Redirect STDOUT and STDERR to main.log
> 3. <Some processing>
> 4. Spawn thread #1:
>    4a. Open thread.log and redirect fd of main.log
> to thread.log
>    4b. Redirect STDOUT and STDERR to thread.log
>    4c. Print few messages to STDOUT, STDERR, fd
>    4d. Fork & exec an external program. (Eg.
> system("ls -l ")
> 
> My problem is that all o/p in 4d goes to the
> main.log. (4c goes to
> thread.log) Once a thread is launched, I'd like to
> have all the o/p go to
> thread.log. Once the thread has exited, I'll append
> thread.log to main.log.
> 
> I guess the reason step 4d does not work is this:
> * Once a thread is launched, STDOUT/STDERR ..etc.
> are 'faked' - ie.
> fileno(STDOUT) != 1
> * When I exec() a program, it's STDOUT = 1, STDERR =
> 2. So anything that's
> printed by the exec'd program goes to main.log.
> 
> Has anyone faced similar issues ? Is there anyway I
> can point STDOUT to fd
> 1 inside a thread ?
> I tried
> open(STDOUT, "<&=1") in the thread but got error
> 'Invalid argument' from
> open.
> 
> I can post a complete script example if needed.
> Appreciate any help.
> 
> thanks
> Sreeji
>  

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