What's a quick way to comment/uncomment lines

Question

I have a Ruby code file open in vi, there are lines commented out with #:

class Search < ActiveRecord::Migration
  def self.up
    # create_table :searches do |t|
    #   t.integer :user_id
    #   t.string :name
    #   t.string :all_of
    #   t.string :any_of
    #   t.string :none_of
    #   t.string :exact_phrase
    # 
    #   t.timestamps
    # end
  end

  def self.down
    # drop_table :searches
  end
end

Say I want to uncomment all the lines in the first def ... end section. What's an efficient way to do that in Vim?

In general, I'm looking for an easy and fluid way to comment and uncomment lines. Here I'm dealing with Ruby code, but it could be JavaScript (//) or Haml (-#).

Answer 1

Sometimes I'm shelled into a remote box where my plugins and .vimrc cannot help me, or sometimes NerdCommenter gets it wrong (eg JavaScript embedded inside HTML).

In these cases a low-tech alternative is the built-in norm command, which just runs any arbitrary vim commands at each line in your specified range. For example:

Commenting with #:

1. visually select the text rows (using V as usual)
2. :norm i#

This inserts "#" at the start of each line. Note that when you type : the range will be filled in, so it will really look like :'<,'>norm i#

Uncommenting #:

1. visually select the text as before (or type gv to re-select the previous selection)
2. :norm x

This deletes the first character of each line. If I had used a 2-char comment such as // then I'd simply do :norm xx to delete both chars.

If the comments are indented as in the OP's question, then you can anchor your deletion like this:

:norm ^x

which means "go to the first non-space character, then delete one character". Note that unlike block selection, this technique works even if the comments have uneven indentation!

Note: Since norm is literally just executing regular vim commands, you're not limited to comments, you could also do some complex editing to each line. If you need the escape character as part of your command sequence, type ctrl-v then hit the escape key (or even easier, just record a quick macro and then use norm to execute that macro on each line).

Note 2: You could of course also add a mapping if you find yourself using norm a lot. Eg putting the following line in ~/.vimrc lets you type ctrl-n instead of :norm after making your visual selection

vnoremap <C-n> :norm

Note 3: Bare-bones vim sometimes doesn't have the norm command compiled into it, so be sure to use the beefed up version, ie typically /usr/bin/vim, not /bin/vi

(Thanks to @Manbroski and @rakslice for improvements incorporated into this answer)

Answer 2

To comment out blocks in vim:

• press Esc (to leave editing or other mode)
• hit ctrl+v (visual block mode)
• use the up/down arrow keys to select lines you want (it won't highlight everything - it's OK!)
• Shift+i (capital I)
• insert the text you want, i.e. %
• press EscEsc

---

To uncomment blocks in vim:

• press Esc (to leave editing or other mode)
• hit ctrl+v (visual block mode)
• use the ↑/↓ arrow keys to select the lines to uncomment.

  If you want to select multiple characters, use one or combine these methods:

  • use the left/right arrow keys to select more text
  • to select chunks of text use shift + ←/→ arrow key
  • you can repeatedly push the delete keys below, like a regular delete button

• press d or x to delete characters, repeatedly if necessary

Answer 3

I like to use the tcomment plugin: http://www.vim.org/scripts/script.php?script_id=1173

I have mapped gc and gcc to comment a line or a highlighted block of code. It detects the file type and works really well.

Answer 4

Specify which lines to comment in vim:

Reveal the line numbers:

:set number

then

:5,17s/^/#/     this will comment out line 5-17

or this:

:%s/^/#/        will comment out all lines in file

Answer 5

Use Control-V to select rectangles of text: go to the first # character, type Ctrl+V, move right once, and then down, up to the end of the comments. Now type x: you're deleting all the # characters followed by one space.

Answer 6

Here's a basic one-liner based on the C-v followed by I method outlined above.

This command (:Comment) adds a chosen string to the beginning of any selected lines.

command! -range -nargs=1 Comment :execute "'<,'>normal! <C-v>0I" . <f-args> . "<Esc><Esc>"

Add this line to your .vimrc to create a command that accepts a single argument and places the argument at the beginning of every line in the current selection.

E.g. if the following text is selected:

1
2

and you run this: :Comment //, the result will be:

//1
//2