code to create daemon in Linux

daemonize.c

#include <unistd.h>
#include <sys/types.h>
#include <syslog.h>
#include <stdlib.h>

int daemonize();
void closelog();

int main(int argc, char **argv)  {
    daemonize();
    openlog("test_daemon", LOG_PID, LOG_USER);
    syslog(LOG_INFO, "%s", "Hello World!");
    closelog();
    return 1; 
}

int daemonize() {
    pid_t pid;
    long n_desc;
    int i;
    
    //Initially fork
    if ((pid = fork()) != 0)    {
        exit(0);
    }
    
    //set session id to make the process group and session group leader
    setsid();
    
    //second fork to make parent exit 
    if ((pid = fork()) != 0)    {
        exit(0);
    }
    
    //change current directory to root and clear the file mask mode
    chdir("/");
    umask(0);
    
    //close all opened FDs
    n_desc = sysconf(_SC_OPEN_MAX);
    for (i = 0; i < n_desc; i++)    {
        close(i);
    }
    return 1;
}