Re: signal, parent & children processes


"Alex Vinokur" <alexvn@xxxxxxxxxxxxxxxxxxxxx> wrote in message news:dmpmvj$oe7$1@xxxxxxxxxxxxxxxxxxxxx
>
> I did something like:
>
> /* --------------------- */
> void sigINT_handler1 (int sig_i)
> {
> fprintf (stderr, "sigINT_handler1: pid#%d ignores a signal %d\n", getpid(), sig_i);
> signal (SIGINT, sigINT_handler1);
> }
>
> void sigINT_handler2 (int sig_i)
> {
> fprintf (stderr, "sigINT_handler2: pid#%d ignores a signal %d\n", getpid(), sig_i);
> signal (SIGINT, sigINT_handler2);
> }
>
>
> int main()
> // fragments od code
> {
> sigINT_handler1 (SIGINT);
>
> if (fork() > 0) // Parent
> {
> // Stuff
> waitpid (pid, &status, 0);
> }
> else // Child
> {
> sigINT_handler2 (SIGINT);
> execvp (<args>);
> }
> }
>
> Parent catchs SIGINT via sigINT_handler1,
> but Child doesn't catch SIGINT via sigINT_handler2.
>
> How can Child catch SIGINT with its own signal handler?
>
[snip]

Actually, what I need is as it follows:
* Parent ignores SIGINT
* Background children ignore SIGINT
* Foreground children have default behavioor on SIGINT

Code below doesn't do that.
Is it possible to change to get desired result?


void sigINT_handler1 (int sig_i)
{
fprintf (stderr, "sigINT_handler1: pid#%d ignores a signal %d\n", getpid(), sig_i);
signal (SIGINT, sigINT_handler1);
}

void sigINT_handler2 (int sig_i)
{
fprintf (stderr, "sigINT_handler2: pid#%d ignores a signal %d\n", getpid(), sig_i);
signal (SIGINT, sigINT_handler2);
}


int main ()
{
while (1)
{

sigINT_handler1 (SIGINT);

read_command_line_and_foreground_flag();

pid = fork();

if (pid < 0)
{
perror ("Unable to execute fork");
continue;
}

if (pid > 0) /* Parent */
{
if (foreground_flag == 1)
{
// Foreground
waitpid (pid, &status, 0);
}
else
{
// Backround
}

}
else /* Child */
{
sigINT_handler2 (SIGINT);
execvp (<args>);
}
}

return 0;

}



--
Alex Vinokur
email: alex DOT vinokur AT gmail DOT com
http://mathforum.org/library/view/10978.html
http://sourceforge.net/users/alexvn




.

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