posix_spawn

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <spawn.h>
#include <sys/wait.h>

static void show_sigmask(const char *when) {
    sigset_t sigs;
    sigemptyset(&sigs);
    int err = sigprocmask(SIG_SETMASK, 0, &sigs);
    if (err) {
        perror("sigprocmask");
        exit(EXIT_FAILURE);
    }
    printf("sigmask %s\n", when);
    int numset = 0;
    for (int i=0; i < 31; i++) {
        if (sigismember(&sigs, i)) {
            printf("  %d\n", i);
            numset++;
        }
    }
    if (numset == 0) {
        printf("  (empty)\n");
    }
}

int main(void) {
    int pid = -1;
    char arg1[] = "/bin/echo";
    char arg2[] = "hello";
    char *argv[] = {arg1, arg2, NULL};
    char *envp[] = {NULL};

    show_sigmask("before posix_spawn");
    (void)posix_spawn(&pid, "/bin/echo", NULL, NULL, argv, envp);
    show_sigmask("after posix_spawn");

    if (pid >= 0) waitpid(pid, NULL, 0);
    return 0;
}