[C] Creating a Daemon Process in C Language

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
int main(int argc, char* argv[])
{
    FILE *fp= NULL;
    pid_t process_id = 0;
    pid_t sid = 0;
    // Create child process
    process_id = fork();
    // Indication of fork() failure
    if (process_id < 0)
    {
        printf("fork failed!\n");
        // Return failure in exit status
        exit(1);
    }
    // PARENT PROCESS. Need to kill it.
    // Because pid > 0 is entering paraent process.
    // So "exit(0)" tell parent to leave.
    
    if (process_id > 0)
    {
        printf("process_id of child process %d \n", process_id);
        // return success in exit status
        exit(0);
    }
    //unmask the file mode
    umask(0);
    //set new session
    sid = setsid();
    if(sid < 0)
    {
        // Return failure
        exit(1);
    }
    // Change the current working directory to root.
    chdir("/");
    // Close stdin. stdout and stderr
    close(STDIN_FILENO);
    close(STDOUT_FILENO);
    close(STDERR_FILENO);
    // Open a log file in write mode.
    fp = fopen ("/tmp/Log.txt", "w+");
    while (1)
    {
        //Dont block context switches, let the process sleep for some time
        sleep(1);
        fprintf(fp, "Logging info...\n");
        fflush(fp);
        // Implement and call some function that does core work for this daemon.
    }
    fclose(fp);
    return (0);
}

Result :

$ gcc -Wall deamon.c -o deamon
$ sudo ./deamon
process_id of child process 2936
$

When cat /tmp/Log.txt will see the string become more and more.
$ cat /tmp/Log.txt
Logging info...
Logging info...
Logging info...
Logging info...

Reference:

• Creating a Daemon Process in C Language with an Example Program