Re: Switching between foreground and background

[Raghuveer <rvk@gsecone.com>]

John T. Williams wrote:

>I think part of the problem here might be conceptual.
>
>If I understand what you want, you'd like, on a signal, for your program to
>go into the background (still running but no longer blocking the terminal
>input/output). On another signal you would like the program to come back to
>the foreground.
>
>If this is the case, the problem you're facing is that the program being in
>the foreground and the background is actually part of the shell, not a
>property of the program running.  Most Shells provide a way to switch
>programs from the foreground to the background and back.
>BASH for example I could type
>
>$>./myprogram
>(cntr + Z) //suspends the current program and prings the prompt back
>$>bg  (runs the program in the background)
>
>The only way that I know of to force a program to run in the background in
>the code is to make it a daemon which is done by forking twice
>
>int main(  ) {
>   if(fork()==0)  {
>            if( fork() == 0 )  {
>                    program code starts here
>             }
>            exit(0);
>    }
>    exit(0);
>}
>  
>
I don't feel it's required to fork() twice for making it a daemon, once 
is enough. Ya, but should use setpgrp() or setpid() and close stdin, out 
and err after the fork and go to infinite loop.

-Raghu

>
>----- Original Message ----- 
>From: "Silambu Chelvan" <silambu_mdu@yahoo.com>
>To: <linux-newbie@vger.kernel.org>
>Sent: Monday, September 22, 2003 6:48 AM
>Subject: Switching between foreground and background
>
>
>  
>
>>Hi all,
>>
>>I have written some program with signal handler. Is
>>this possible, if
>>one of the signals registered with my program is
>>raised, my program
>>should goto background and should come to foreground
>>when some other of the
>>registered signal is raised. how to do it?
>>
>>Any function available to switch a process between
>>foreground and
>>background at runtime?
>>
>>with regards,
>>M. SilambuChelvan
>>
>>
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