提权

sudo passwd root

允许root登录

nano /etc/ssh/sshd_config

1. 输入 nano /etc/ssh/sshd_config 回车

2. 2

   找到

   # Authentication: LoginGraceTime 120 PermitRootLogin without passwd StrictModes yes

3. 3

   把“PermitRootLogin without passwd”改成“PermitRootLogin yes”

   按“ctrl+o”保存再退出，退出后记得要重启一下才生效！

4. Simply adding a password for root is not enough for Ubuntu 14.04 Server.

   You also need to edit/etc/ssh/sshd_config,and comment out the following line:

   PermitRootLogin without-password

   Just below it,add the following line:

   PermitRootLogin yes

   Then restart SSH:

   service ssh restart

创建文件,编辑文件

touch t.py

nano t.py

文件合并,读取的文件不能是输出的文件

cat t.py t1.txt > t2.txt

将文件内容追加到另一个文件的后面

cat t1.txt t2.txt >> t.py

使用tree

apt-get -y install tree

tree

效果如下