Is there any way to send a value through signal

Question

I am programming a program with 2 process, parent process forks to generate a child process. And my problem is that i wanna send a value from parent to child in a most simple way. Can i do it with signal or any other IPC(most simple). Thank All !!!

Answer 1

Data can be sent/received with a signal - at least on systems supporting sigqueue() and sigaction() with SA_SIGINFO. Example for the receiving process:

#include <signal.h>
#include <string.h>

void usr1(int sig, siginfo_t *sip, void *ptr)
{
    printf("sival_int %d\n", sip->si_value.sival_int);
}

. . .

    struct sigaction sa;

    memset(&sa, 0, sizeof (sa));
    sa.sa_sigaction = usr1;
    sa.sa_flags = SA_SIGINFO;
    sigaction(SIGUSR1, &sa, NULL);

Example for the sending process:

#include <signal.h>

. . .

    union sigval sv;

    sv.sival_int = 43210;
    sigqueue(target_pid, SIGUSR1, sv);

See union sigval for another choice.
Manual pages: sigaction, sigqueue