p5-13.c

UNIX程序设计教程

#include <stdio.h>
#include <unistd.h>
#include <limits.h>
#include "err_exit.h" 
int main(void)
{
    int uid,euid;
    if(getlogin()==NULL)
       err_exit("getlogin error");
    printf("login_name is: %s\n", getlogin());
    printf("cuser_name is: %s\n", cuserid(NULL));       
    printf("real uid is: %d\n", getuid());
    printf("effective uid is: %d\n", geteuid());
}