You can use vi text editor in Unix

vi [-eFGlRrSv] [-c cmd] [-t tag] [-w size] [file]

Vi is a screen oriented text editor. vi have different interfaces to the same program, and it is possible to switch back and forth during an edit session. View is the equivalent of using the -R (read-only) option of vi.

Command input for vi is read from the standard input. In the vi interface, it is an error if standard input is not a terminal.

Vi is a screen editor. This means that it takes up almost the entire screen, displaying part of the file on each screen line, except for the last line of the screen. The last line of the screen is used for you to give commands to vi, and for vi to give information to you.

The other fact that you need to understand is that vi is a modeful editor.

Ex:
dd Delete the line the cursor is on.
x Delete the character the cursor is on.
:w Save the Works that u done
:q Quit from vi editor
:q! Quit without saving the work that you edit

Do check your Unix system vi man pages for more info