First Exploration with GNU/Linux
After booting and finishing system initialization, the follow message is displayed with a character interface:
Debian GNU/Linux 8 debian tty1
debian login: _
Enter your username and password set during the installation. Note that when you enter the password, your input will not be displayed on the screen.
After logging in, you will see the following prompt:
username@hostname:~$
This working environment is call terminal. This prompt shows your username, host name, and the current working directory. The current working directory is ~ now. As you switching to another directory, the prompt will change as well. You are going to finish all the experiments under the environment, so try to make friends with terminal!
Many of you always use operating system with GUI, such as Windows. The Debian you just installed is without GUI. It is completely with CLI (Command Line Interface). As you logging in the system, you may feel empty, depress, and then panic...
Calm down yourself. Have you wondered if there is something that you can do it in CLI, but can not in GUI? Have no idea? If you are asked to count how many lines of code you have coded during the 程序设计基础 course, what will you do?
If you stick to Visual Studio, you will never understand why vim is called 编辑器之神. If you stick to Windows, you will never know what is Unix Philosophy. If you stick to GUI, you can only do what it can; but in CLI, it can do what you want. One of the most important spirits of young people like you is to try new things to bade farewell to the past.
GUI wins when you do something requires high definition displaying, such as watching movies. But in our experiments, GUI is unnecessary. Here are two articles discussing the comparision between GUI and CLI:
Now you can see how much disk space Debian occupies. Type the following command (every command is issued by pressing the Enter key):
df -h
You can see that Debian is quite "slim".
Installing a Windows operating system usually requires much more disk space as well as memory. Can you figure out why the Debian operating system you installed can be so "slim"?
To shut down the VM, it is recommended to issue command instead of closing the VM window rudely (just like you shut down Windows by the start menu, instead of unplugging the power):
poweroff
However, you will receive an error message:
-bash: poweroff: command not found
This error is due to the property of the poweroff command - it is a system administration command. Execute this command requires superuser privilege.
Can you provide a scene where bad thing will happen if the poweroff command does not require superuser privilege?
Therefore, to shut down the VM, you should first switch to the root account:
su
Enter the root password you set during the installation. You will see the prompt changes:
root@hostname:/home/username#
The last character is #, instead of $ before you executing su. # is the indicator of root account. Now execute poweroff command again, you will find that the command is executed successfully.
你务必通过poweroff命令关闭虚拟机, 如果你通过点击窗口右上角的X按钮强制关闭虚拟机, 可能会造成虚拟机中文件损坏的现象. 往届有若干学长因此而影响了实验进度, 甚至由于损坏了实验相关的文件而影响了分数, 请大家引以为鉴, 不要贪图方便, 否则后果自负!