pid로 uid 알아내기

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
 
int main (void) {
    int pid = getpid ();
    char path[64] = { 0, };
    struct stat st;
 
    sprintf (path, "/proc/%d/stat", pid);
 
    if ( stat (path, &st) == -1 ) {
        fprintf (stderr, "path is something worng (%s)\n", path);
        exit (1);
    }
 
    printf ("The UID of %s is %d\n", path, st.st_uid);
    return 0;
}