Date: Mon, 10 Jul 1995 12:55:22 +0900 From: Toshihiro Kanda <candy@fct.kgc.co.jp> To: freebsd-questions@freebsd.org Subject: How can I block a signal? Message-ID: <199507100355.MAA25071@xxx.fct.kgc.co.jp>
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Hi. Someone please teach me how to block a signal. My system is:
>$uname -mrs
>FreeBSD 2.0-RELEASE i386
The friendly manual sigprocmask(2) says "Signals are blocked if they
are members of the current signal mask set." But it doesn't seem to
block. I tested the following program.
---8<------8<------8<------8<------8<---
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
void onintr(int x) { write(2, "!", 1); }
int main(void)
{
sigset_t mask = sigmask(SIGUSR1);
signal(SIGUSR1, onintr);
raise(SIGUSR1);
sigprocmask(SIG_BLOCK, &mask, NULL);
write(2, "block\n", 6);
raise(SIGUSR1);
mask = sigmask(SIGUSR1);
sigprocmask(SIG_UNBLOCK, &mask, NULL);
write(2, "unblock\n", 8);
return 0;
}
---8<------8<------8<------8<------8<---
I expected it output:
>!block
>unblock
>!
But it output:
>!block
>!unblock
Why? Is this correct and am I misunderstanding? If so, how can I block
a signal?
Thank you.
candy@fct.kgc.co.jp (Toshihiro Kanda)
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