Linux Learnning

1. what is the IP address and network card

a. network card is a kind of hardware device that have the duty to make computer communite each other.
b. IP is the address inseted int he network
if the phone is computer, network card is like SIM card, and the IP is like phone number.

the name of netwrok card is just a mark and not the key ,and the key is the cooresponding address !

2. ifconfig and ping
ifconfig order / command is used for checking and config the configeration information of netwrok card.
ifconfig | grep inet (give the )
ping check the connection to the target IP address,

ping IP address / ping 127.0.01 (check local nerwork card)

SSH /SCP
Data transmission is encrypted to prevent information leakage.
Data transmission is compressed, which can improve transmission speed.

域名，端口号 IP address
域名是IP address 的别名，方便记忆 （www.itcast.cn）
so, ping + domin name

send a data package with the 56 bytes, and receive 64 bytes from the other computer which you are commucate with the Ip addresss of 220.181.112.244, and cosuming time is “time = 2.08 ms”

端口号： 找到服务器上运行的应用程序

SSH: [-p port] user@remote
ssh -X (需要图传配置选项)

scp -P port file1 user@remote:
scp -P 22 -r user@remote:Desktop 复制文件夹

文件和文件夹的transmition direction is From firest file to secontd file.

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change the access of files or directory
ls -l : shows the access of files
oreder form:
chmod _/+ rwx directory/files name

surpervisor user

group / user / file
a file only belongs a grop
a user can belongs some grops and a group and includs some users


today, the group / user / 文件的读写执行权限问题

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明天学习 Cmakelist.txt 文件的内容。

关机指令for ubuntu:

poweroff / halt / shoutdown