xy2@OptiPlex:~/yuan/scp$ pwd
/home/xy2/yuan/scp
sudo -i
enter /root path
xy2@OptiPlex:~/yuan/scp$ sudo -i
root@OptiPlex:~# pwd
/root
root@OptiPlex:~# exit
logout
sudo -s
enter current path
xy2@OptiPlex:~/yuan/scp$ sudo -s
root@OptiPlex:~/yuan/scp# pwd
/home/xy2/yuan/scp
root@OptiPlex:~/yuan/scp# exit
exit
