[C Linux] Kako iz UID dobit username?

#include <stdio.h>
#include <stdlib.h>
#include <pwd.h>
#include <sys/types.h>

int main(int argc, char *argv[])
{
    if (argc != 2) {
	printf("Uporaba: %s uid\n", argv[0]);
	exit(1);
    }
  		
    uid_t uid = atoi(argv[1]);
    struct passwd *pw;
	
    pw = getpwuid(uid);
    if (pw != NULL) {
    	printf("UID=%d, GID=%d, IME=%s, HOME=%s, SHELL=%s\n",pw->pw_uid, pw->pw_gid, pw->pw_name, pw->pw_dir, pw->pw_shell);
    }

    exit(0);
}