*
When landing root And @ There is no space between
*
mv Command to cut , Change file name and other functions
*
cp command -i The command asks before overwriting
*
cat Press enter after obtaining from the keyboard to display on the screen , Read small files
*
tac And cat corresponding Reverse order printing
*
more command Display for easy reading
*
| The Conduit
*
dmesg Print log
*
grep filter
dmesg | grep err |more -3 Combination of commands
*
journal
*
echo Print -e( Show special characters ) redirect （>）
*
“>” redirect ">>" Append redirection , Write from end of file , Historical data will be saved
*
“<” input redirection
*
less And more Functional similarity /+ Digital search
-N set number q Can stop
*
head Get the first ten lines of the document You can also specify how many lines to get in front
*
tail Get the last ten lines of the document You can also specify how many rows to get
*
Get time date
Format printable time
time stamp date+%s （1970/1/1 Number of seconds from zero to now Zero here is equivalent to eight o'clock Beijing time ）
date +%Y/%m/%d+%H:%M:%S It can be transformed into understandable time
date -d@ Timestamp conversion （@0 Is the time when the timestamp starts The time difference is eight hours ）
*
cal Calendar instruction
*
grep Text line filter tool Facilitate text processing
grep -E regular expression
-v Reverse selection （ be similar to C Logical non in language ）
-i ignore case
-n Output line number
grep With printing function
*
find Disk discovery command High cost of discovery
*
which Specifically find the path where the command is located
whereis As long as the keywords are included, they will be found （ No spaces ）
*
alias ls -l And ll
ls -l --color=auto Alias is ll
Put it another way ：ll yes ls -l Alias with specific options
alias Custom alias as alias lll=‘ls -l -i --color=auto’ (color It's for coloring )
Cancel alias ： Turn off the terminal and it's gone Or set to null
*
Packing compression , Unpack
zip pack ：
zip xx.zip xx
Packaged zip The file is in the current directory by default
Use when packaging multiple directories -r （ Recursive ）
unzip Unpack ：
unzip xx.zip -d route
The unpacked files are in the current directory by default
-d Specify the extracted file path
tar：（ There is no short bar connection between ）
tar czf c establish z Compressed package f New name Create a compressed file with the extension tgz
tar cvzf Yes v The packaging process is displayed after
tar xzf x Unzip the package
tar xvzf Show unpacking process
tar xzf xx.zip -C route Unzip to the specified path
Reasons for packaging compression ： Multiple files are packaged into one file , Reduce file loss due to network and other reasons （ pack ）, You can also reduce the volume （ compress ）
*
tree Tree display
*
bc Calculator Add other commands to control accuracy
*
uname -a View host name , Current machine version , Kernel name , Kernel version , Architecture and other information
*
ctrl+r stay XShell You can search the original command in the
*
history Displays all commands that have been tapped
*
Tab Key can be automatically supplemented （ Press twice to get a conditional command ）
*
ctrl+c End process
*
ctrl+d amount to exit Press several times to exit the account /XShell
*
shutdown
-h Shut down immediately
-r Restart after service shutdown
-t sec How many seconds will it shut down
*
reboot restart
*
Sign in linux The system creates a process for the user Generally called bash（ Command Line Interpreter ）
user -> shell Shell -> linux kernel
*
What is? shell? Software layer wrapped outside the operating system It is also a command line interpreter
*
Why does it exist shell? Solve the problem that users are not good at dealing with the operating system Deliver requests and feedback Protected operating system
*
shell And bash Relationship between ?shell Is a class bash It's a concrete one （ Kind of like java Instantiation in ）
*
jurisdiction ： Super user （root） And ordinary users
*
Switch users su - ( Ordinary users -> Super user )
*
increase root Password security
*
su + user name Switch users
*
useradd ->sudo passwd user name ->userdel -r user name （ No -r Delete not clean The directory will be left ）
*
sudo Temporarily increase permissions , Error reporting solution ： configuration file , change /etc/sudoers File content in
Technology