#include <unistd.h>
#include <pwd.h>
#include <sys/types.h>
#include <stdio.h>
int main(int argc, char **argv)
{
    pid_t my_pid, parent_pid;//*_t 均为int类型
    uid_t my_uid, my_euid;
    gid_t my_gid, my_egid;
    struct passwd *my_info;
    my_pid = getpid();
    parent_pid = getppid();
    my_uid = getuid();
    my_euid = geteuid();
    my_gid = getgid();
    my_egid = getegid();
    my_info = getpwuid(my_uid);//可以指定用户id
    printf("Process ID：%d\n", my_pid);
    printf("Parent ID：%d\n", parent_pid);
    printf("User ID：%d\n", my_uid);
    printf("Effective User ID：%d\n", my_euid);
    printf("Group ID：%d\n", my_gid);
    printf("Effective Group ID：%d\n", my_egid);
    if (my_info) {
        printf("My Login Name：%s\n", my_info->pw_name);
        printf("My Password ：%s\n", my_info->pw_passwd);
        printf("My User ID ：%d\n", my_info->pw_uid);
        printf("My Group ID ：%d\n", my_info->pw_gid);
        printf("My Real Name：%s\n", my_info->pw_gecos);
        printf("My Home Dir ：%s\n", my_info->pw_dir);
        printf("My Work Shell：%s\n", my_info->pw_shell);
    }
    return 0;
}