#include <unistd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/file.h>
#include <sys/un.h>

#define sock_path "/tmp/.s.PGSQL.5432"

main() {
    struct sockaddr_un saddr;
    int fd, lock_fd;
    
    memset((char *) &saddr, 0, sizeof(saddr));
    saddr.sun_family = AF_UNIX;
    strcpy(saddr.sun_path, sock_path);
    fd=socket(PF_UNIX, SOCK_STREAM, 0);
    if (fd>=0) {
	bind(fd, &saddr, SUN_LEN(&saddr));
	if ((lock_fd = open(sock_path, O_WRONLY | O_NONBLOCK, 0666)) >= 0) {
	    struct flock lck;

	    lck.l_whence = SEEK_SET;
	    lck.l_start = lck.l_len = 0;
	    lck.l_type = F_WRLCK;
	    fcntl(lock_fd, F_SETLK, &lck);
	}
    }
}