The vi editor is a powerful text editor used in Unix-like operating systems, including Linux. It’s known for its efficiency and versatility, although it has a steep learning curve for beginners.

Here’s an overview of vi:

1. Modes:

Insert Mode  – Allows you to insert and edit text.

Command Mode – Used for executing commands and navigating the file.

          Visual Mode  – Used to highlight and edit text in bulk.

2. Basic Navigation:

h, j, k, l – Move left, down, up, right respectively.

Arrow keys –  Same as h, j, k, l.

:0 (zero) Move to the beginning of the current line.

:$ Move to the end of the current line.

:gg Move to the beginning of the file.

:G Move to the end of the file.

3. Basic Editing:

i – Enter insert mode before the cursor.

a – Enter insert mode after the cursor.

o – Open a new line below the current line and enter insert mode.

O – Open a new line above the current line and enter insert mode.

x – Delete the character under the cursor.

dd – Delete the current line.

yy – Copy (yank) the current line.

p – Paste the copied or deleted text after the cursor.

4. Saving and Exiting:

:w –  Save changes to the file.

:q – Quit vi (only if no changes have been made).

:q! – Quit vi without saving changes.

:wq or ZZ Save changes and quit.

5. Search and Replace:

/pattern –  Search forward for a pattern.

?pattern – Search backward for a pattern.

n – Repeat the last search in the same direction.

N – Repeat the last search in the opposite direction.

:s/pattern/replace – Replace the first occurrence of a pattern with a replacement.

:s/pattern/replace/g – Replace all occurrences of a pattern with a replacement.

6. Miscellaneous:

u  – Undo the last change.

Ctrl + r – Redo the last undone change.

:set number – Display line numbers.

:set nonumber – Hide line numbers.

The vi editor is a versatile and powerful text editor that provides extensive features for editing text files in Linux. While it has a steep learning curve, mastering vi can greatly enhance your productivity and efficiency when working with text files in a terminal environment. Practice and familiarity with vi will gradually make you more proficient in using this essential tool for Linux system administration and development tasks.