How do I repeat an edit on multiple lines in Vim?

I'm aware that in Vim I can often repeat a command by simply adding a number in front of it. For example, one can delete 5 lines by:

5dd

It's also often possible to specify a range of lines to apply a command to, for example

:10,20s:hello:goodbye:gc

How can I perform a 'vertical edit'? I'd like to, for example, insert a particular symbol, say a comma, at the beggining (skipping whitespace, i.e. what you'd get if you type a comma after Shift-I in command mode) of every line in a given range. How can this be achieved (without resorting to down-period-down-period-down-period)?

Ctrl-v enters visual mode blockwise. You can then move (hjkl-wise, as normal), and if you want to insert something on multiple lines, use Shift-i.

So for the text:

abc123abc
def456def
ghi789ghi

if you hit Ctrl-v with your cursor over the 1, hit j twice to go down two columns, then Shift-i,ESC , your text would look like this:

abc,123abc
def,456def
ghi,789ghi

(the multi-line insert has a little lag, and won't render until AFTER you hit ESC).

:10,20s/^/,/

Or use a macro, record with:

q a i , ESC j h q

use with:

@ a

Explanation: q a starts recording a macro to register a, q ends recording. There are registers a to z available for this.

That's what the :norm(al) command is for:

:10,20 normal I,

If you are already using the '.' to repeat your last command a lot, then I found this to be the most convenient solution so far. It allows you to repeat your last command on each line of a visual block by using

" allow the . to execute once for each line of a visual selection
vnoremap . :normal .<CR>

I believe the easiest way to do this is

1. record a macro for one line, call it 'a'; in this case one types

> q a I , ESC j q

2. select the block of lines that you want to apply the macro to

3. use the 'norm' function to execute macro 'a' over this block of lines, i.e.,

> :'<,'>norm@a

I think the easiest is to record a macro, and then repeat the macro as many times as you want. For example to add a comma at the start of every line, you type:

q a I , ESC j q

to repeat that 5 times, you enter

5 @ a

With your edit already saved in the . operator, do the following:

1. Select text you want to apply the operator to using visual mode
2. Then run the command :norm .

Apart from the macros, as already answered, for the specific case of inserting a comma in a range of lines (say from line 10 to 20), you might do something like:

:10,20s/\(.*\)/,\1

That is, you can create a numbered group match with \( and \), and use \1 in the replacement string to say "replace with the contents of the match".

I use block visual mode. This allows you to perform inserts/edits across multiple lines (aka 'vertical edits').