how to read a txt file from terminal ?

how to read a txt file from terminal ? 

open the terminal

enter as administrator ( root ) with the following command :

su 

then type password

type the following command :

vi file_name

for example :

I want to read the file amine.txt

vi amine.txt

to change a word type on the letter i

to exit the vi text editor with change press the esc button and type 

:wq 

w = write 

q = quit 

to exit the vi text editor its backup press the esc button and type

q!

q= quit 

! = confirmation