方法一：执行命令whoami
[root@test01 ~]# whoami
结果如下：
root
方法二：执行命令lastlog
[root@test01 ~]# lastlog
结果如下：
Username Port From Latest root pts/0 10.0.0.1 Fri Aug 31 09:11:19 +0800 2018 bin **Never logged in** daemon **Never logged in** adm **Never logged in** lp **Never logged in** sync **Never logged in** shutdown **Never logged in** halt **Never logged in** mail **Never logged in** operator **Never logged in** games **Never logged in** ftp **Never logged in**
