1. Shell echo > and echo > >

echo -e "hello world\n" >> ./.git/config
# meaning ： hold hello world And the newline symbol is appended to /.git/config This file 

Look at this line of code ：

echo Indicative output , amount to c In language printf function .

• No -e Option echo, take \n It is considered to be ordinary characters ;
• Used -e Option echo, Will \n Consider it a line break .

As for the back >> accord with , Look below .

The following is from ：https://www.cnblogs.com/singeryoung/p/9554551.html
author ： The sun, the moon and the stars

echo > Output redirection

echo>> Output additional redirection

echo hello A

The string hello A Output to the screen

echo hello A > tmp.txt

Redirect string output , The current directory does not have tmp.txt, Create tmp.txt, And output the string to tmp.txt In file

tmp.txt Content ：hello A

echo hello B > tmp.txt

Redirect string output , The current directory exists tmp.txt, Will tmp.txt Replace the content with the output string

tmp.txt Content ：hello B

echo hello C >> tmp.txt

Append the string output to redirection , The current directory exists tmp.txt, Will tmp.txt Append the output string after the content of

tmp.txt Content ：hello B hello C

therefore , Meaning is ： hold hello world And the newline symbol is appended to /.git/config This file .