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Lesson 4 Using a text editor
Objective Use the vi text editor.
Shell scripts are text files. They cannot contain any special formatting or font information. Shell scripts can be created in any word processor or text editor, as long as they are saved as plain text files.
Some text editors can color code shell scripts, highlighting comments, commands, and variables. This information is to help you understand the script. The formatting and colors are not saved as part of the text file.

Why use vi?
The most well-known text editor on modern UNIX systems is the vi editor. UNIX systems have other editors, including graphical editors that are easy to use. But because vi is available on all UNIX systems, we will use it as the basis for writing our shell scripts. The information presented in this lesson should be a review for you. It’s not easy to use vi until you have mastered a few of its fundamentals.
The vi text editor has several modes. The two main modes you will use are command mode and insert mode. In command mode, characters that you enter are interpreted as commands; in insert mode, characters that you type are entered as part of your document. After inserting text (or if you are not sure what mode you are in), you can always change to command mode by pressing the Esc key, which toggles between the two modes.
Basic vi commands
The following table describes some basic commands in vi.
Unix Text Editor - Exercise
Click on the Exercise link below to practice using vi in the UNIX Lab.
Unix Text Editor - Exercise
The next lesson introduces a command to write information to the screen from a script.