47 lines
872 B
C
47 lines
872 B
C
#include <fcntl.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <sys/stat.h>
|
|
#include <sys/types.h>
|
|
#include <unistd.h>
|
|
|
|
#define NR_OPEN 1048576
|
|
|
|
int main(void)
|
|
{
|
|
// create new process
|
|
pid_t pid = fork();
|
|
if (pid == -1) {
|
|
return -1;
|
|
} else if (pid != 0) {
|
|
printf("Running daemon with pid %d\n", pid);
|
|
exit(EXIT_SUCCESS);
|
|
}
|
|
|
|
// create a new session and process group
|
|
if (setsid() == -1)
|
|
return -1;
|
|
|
|
// set the working directory to the root directory
|
|
if (chdir("/") == -1)
|
|
return -1;
|
|
|
|
// close all open files--NR_OPEN is overkill, but works
|
|
for (int i = 0; i < NR_OPEN; i++) {
|
|
close(i);
|
|
}
|
|
|
|
// redirect fd's 0,1,2 to /dev/null
|
|
open("/dev/null", O_RDWR); // stdin
|
|
dup(0); // stdout
|
|
dup(0); // stderr
|
|
|
|
// do its daemon thing
|
|
for (int i = 0; i < 10; i++) {
|
|
printf("Hello from daemon %d\n", getpid());
|
|
sleep(1000);
|
|
}
|
|
|
|
return 0;
|
|
}
|