framebuffer和X都需要对分辨率进行设置，而gtf就是为此而生的工具。

e.g.

gtf 1024768 60 -x

可以得到1024×768@60Hz的Modeline设置。

"Raising Elephants Is So Utterly Boring" means:

1. Alt + SysRq + R – takes the keyboard out of raw mode.
2. Alt + SysRq + E – terminates all processes (except init).
3. Alt + SysRq + I – kills all processes (except init).
4. Alt + SysRq + S – synchronizes the disk.
5. Alt + SysRq + U – remounts all filesystems read-only.
6. Alt + SysRq + B – reboots the machine.

An alternative to issuing the REISUB/RSEIUB keystrokes is to just press Alt + SysRq + R, followed by Ctrl + Alt + Del. This is the equivalent of issuing a shutdown now command at a root console; it does take a short while for the system to shut down after the Ctrl + Alt + Del keystroke. However, not all Linux systems support this easier method.

参考文献: http://www.pixelbeat.org/docs/screen/

启动一个命名screen

screen -S shared

开启多用户模式

C-A: multiuser on

加入用户

C-A: addacl ywayne,yuting,leiyh

设置用户只读权限

C-A: aclchg ywayne,yuting,leiyh -wx "#,?"
C-A: aclchg ywayne,yuting,leiyh +x "colon,detach,wall"

这里允许执行的三个命令里colon是指C-A之后输入的那个冒号(真不理解冒号也是命令！？)。detach是允许客户不想看的时候可以用C-A D离开screen(强奸客户们的意图是不好滴)。wall是让客户可以使用wall命令向所有发言，方便演示过程中提问。

客户登录

screen -x jianingy/shared