I think part of the problem here might be conceptual.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.
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);
}
-Raghu
----- Original Message ----- From: "Silambu Chelvan" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
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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