Linux Note 3 20160715_2

vi, vim

vi is a very strong command line edit software.
vim was the advanced version of vi, adding the support of GUI.
Except vim, emacs is even stronger than vim.

vim + path to use vim

three modes of vi

• command mode
  default
  i : insert text at the cursor
  o : insert a new line below the current one
  dd : delete the whole row
  yy : put the current row's content to the ram(copy the current line)
  n+yy: put n rows' content to the ram(copy n lines)
  p : paste
  u : revoke the last manipulation
  r : replace current character
  / : find key word

• insert mode
  i
  Esc : back to the command mode

• ex mode
  :

:w     #save
: q    #quit
:q!    #force to quit
:set number    #show the line number
:! system command # execute a system command
:sh #return to the command line  and 'ctrl + d' can return to the vim 

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Basic concept of disc

转速越快，磁盘性能越强。但是，功率发热量都会高。
SATA

• 柱面(cylinder)
  立体，多碟片叠加的柱面圈
• 扇区(sector)
  中心扩散出来的扇形
• 磁头(head)
  读写数据，每个磁盘上下都有个磁头

磁盘在linux中的表示

设备名称一般为hd[a-z]或sd[a-z]，如hda,hdb,sda,sdb
IDE设备的名称为hd[a-z],SATA,SCSI,SAS,USB等设备名称为sd[a-z]

concept of partition

将一个磁盘逻辑的分为几个区，每个区当作独立磁盘，以方便管理。
不同分区用： 设备名称 + 分区号 ，如sda1,sda2
主流的分区机制分为MBR和GPT两种。

MBR

Master Boot Record. Traditional one. Applied to most BIOS PC device.

• support 32bit and 64bit
• there is a limit for partition
• support no more than 2T hard disk.

MBR partition

• main partition
  at most 4
• extended partition
  take a place of the main partition.
  can't be used. still need logical partition.
• logical partition
  can only be created by creating an extended partition first.
  Linux can support at most 63 IDE partition and 15 SCSI partition.

GPT

A new one.

• support more than 2T
• compatible with MBR
• only can be used on the hardware that supports UEFI
• only 64bit
• Mac,Linux both support GPT
• Windows 7 64bit, windowsServer2008(win10,win8?)