The editor vi (visual editor shorthand) is a screen editor that is available on almost all Unix systems. the vi editor is a fast and powerful visual to edit the various configuration files for example for managing your servers, for example an Unmanaged VPS with Linux OS without using the web-based panel and all you need is an SSH terminal client with the root account. More about vi and vi developer Billy Joy.

A short tutorial how to use vi editor on Linux, where in this guide you can learn the command-command is most commonly used when editing text file using vi editor. This simple post can you learn to learn to use the vi editor to edit the configuration files for the client to manage your VPS hosting.
The use of Basic vi. To start using vi, type as following example, then Enter
# vi nama_file.conf
After the file is open for editing, or start the insert type
i
To exit the insert mode or edit mode, press
Ctrl+C
After coming out of insert mode, to save the results of the edit at once out of the vi editor, press
ZZ or type: wq
But if you just want to keep but still not want to exit from the vi editor, type
:w
Whereas, to exit without saving
:q!
As for searching for words/characters in the Previous line
?
Examples of the use of e.g. type/date, then enter:
?date
To search for words/characters in the Next line
/
To return to command mode
Esc
To delete 1 line type dd command mode when [on the line you want to delete.
dd
For other orders please look at manual vi through command prompt
man vi
I think, On Linux CentOS default text editor is vi that have been installed in the system. You may want to learn another text editor like vim, nano and pico editor. But in my opinion type vi quicker than typing the command editor