Note 1

Chapter 5. System Category Structure

ls = list

useradd XXX (home category is /home)

authorized_keys must be under .ssh (stipulated by sshd configuration ----- ls /etc/ssh/sshd_config)

Catalogue

bin & sbin

command under sbin is basically used by root account and bin is used by normal account (sbin means super bin)

boot

boot up related files (grub- like singleuser mode)

dev

device files(mouse, keyboard etc..)

/etc

system configuration files (Network card setup files: ls /etc/sysconfig/network-scripts/ifcfg-ens33 & ls /etc/ssh/sshd_config)

Excerpted from https://zhidao.baidu.com/question/398779738.html

/home

home category of users

lib & lib 64

for dll (Dynamic Link Library)

 

Excerpted from https://baike.baidu.com/item/%E5%BA%93%E6%96%87%E4%BB%B6/2550595

/proc

Excerpted from https://www.cnblogs.com/DswCnblog/p/5780389.html

/run

Temp file when system progressing, only exsit before system reboot

/sys

core related files

/tmp

temp directory

/usr

user files

/var

Excerpted from https://zhidao.baidu.com/question/398779738.html

/var/log : log files

Chapter 6. Frequent command

/tree (install command firstly: yum install -y tree)

Man tree

tree -L (level, max display depth of the directory tree) eg. Tree -L 2 /

/ls

*inode please refer to https://www.cnblogs.com/itech/archive/2012/05/15/2502284.html

**File type

capital letter

"d" for directory

"-" for normal file (can be checked by "cat" command directly)

"c" for character device (yellow color), mouse keyboard, tty file

Excerpted from https://baike.baidu.com/item/%E5%AD%97%E7%AC%A6%E8%AE%BE%E5%A4%87/6637035

"b" for block device (disk)

“s” for socket file. communication, data transmission

"l" for symbolic link. 符号链接 又称软连接，包含了另一个文件的绝对路径或者相对路径

Excerpted from https://baike.baidu.com/item/%E5%A5%97%E6%8E%A5%E5%AD%97/9637606?fr=aladdin

alias

Add new command (fred) into alias: alias fred='ls -lha' / unalias to cxl the comand add-in

CD

cd - alternate to previous command

cd move to the home directory of current directory

cd ~ go back to user's home directory

cd .. go back to previous directory

mkidr/ rmdir and rm

if directory 1/2 needed to be created simultaneously, try to use -p after mkdir/rmdir, (-pv for visually)

touch for file creating touch /tmp/1/2/1.txt

rm unsed to remove the files, use -f after rm command and skip the notification and delete directly

notes ! command also can be used, refer to most recent command in history

!$ refer to the last character in most recent command in history

rm -r to remove all directory and files

cp

cp A B

cp -r if copy a directory

Chapter 7. Path

Absolute Path & Relative Path

 

Excerpted from https://baike.baidu.com/item

if your command is under one of below directory, we dunt need to input absolute Path

How to add /tmp/ into PATH? (temprorary)

How to add /tmp/ into PATH? (permenant)