Changing Text in vi
In addition to "standard" editing, there are a several special editing commands.
Pressing dd will delete the entire line you are on; 5dd would then
delete five complete lines. To open up a line for editing, we press o to open the line after the line you are
currently on and O for the line before. Use x to delete the character (including numbers) that the cursor is on.
When we want to move something we just deleted, we put the cursor
on the spot where we want it. Then press either p to put that text
after the current cursor position or P to put it before the current position. A nice trick that I
always use to swap characters is xp. The x deletes the character you are on and the p immediately
inserts it. The result is that you swap characters. So if I had typed the word "into" as "inot," I would
place the cursor on the "o" and type xp, which would swap the "o" and the "t."
To repeat the edit we just did, be it deleting 18 lines or inputting "I love you," we could do so by pressing "." (dot)
from command mode. In fact, any edit command can be repeated with the dot.
To make a change, press c followed by a movement command or number and movement command.
For example, to change everything from where you are to the next word, press cw. To
change everything from where you are to the end of the line, press C or c$. If you do that,
then a dollar sign will appear, indicating how
much you intend to change.
If we go back into command mode (press Esc) before we reach the dollar sign, then everything from the current
position to the dollar sign is removed. When you think about this, it is actually logical. By pressing C, you tell vi that
you want to change everything to the end of the line. When you press Enter, you are basically saying that you are
done inputting text; however, the changes should continue to the end of the line, thereby deleting the rest of the line.
To undo the last edit, what would we press? Well, whats the first letter of the word "undo"? Keep
in mind that pressing u will only undo the last change. For example, lets assume we enter the following:
o to open a new line and go into input mode
Esc to go back to command mode
a to append from current location
Esc to return to command mode
The result of what we typed was to open a new line with the text
"I love you." We see it as one change, but from the perspective of vi, two changes were made. First we entered
"I love," then we entered "you." If we were to press u, only "you" would be removed. However, if u undoes that last change,
what command do you think returns the line to its original state? What else: U. As you are making changes, vi keeps track
of the original state of a line. When you press U, the line is returned to that original state.
If you want to replace all of the text on the current line, you could simply delete the line and insert a
new one. However, you could also replace the existing line by using the R (for replace) command. This
puts vi into replace mode and each character you type replaces the existing characters as you write.