daemons in c code example

Example: Daemon Processes program

#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.
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 ("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);
}