[keyboard-shortcuts] Shortcut to comment out a block of code with sublime text

I want to comment out a block of code in sublime text.

I see it in RailsCasts, but don't think he uses sublime text ... to do the following ...

if (uncommented)
  some uncommented example
  # if (commented) 
  #   some commented example code
  # end
end

Is there a shortcut in sublime text that I can use to insert the block of #'s?

Just an important note. If you have HTML comment and your uncomment doesn't work
(Maybe it's a PHP file), so don't mark all the comment but just put your cursor at the end or at the beginning of the comment (before ) and try again (Ctrl+/).

You can toggle the block comment with

Ctrl+Shift+/

Source: http://www.sublimetext.com/forum/viewtopic.php?f=3&t=2967

Just in case someone is using the Portuguese ABNT keyboard layout The shortcut is

Ctrl + ;

With a non-US keyboard layout the default shortcut Ctrl+/ (Win/Linux) does not work.

I managed to change it into Ctrl+1 as per Robert's comment by writing

[
{
    "keys": ["ctrl+1"],
    "command": "toggle_comment",
    "args": { "block": false } 
}
,
{   "keys": ["ctrl+shift+1"],
    "command": "toggle_comment",
    "args": { "block": true }
}
]

to Preferences -> Key Bindings (on the right half, the user keymap).

Note that there should be only one set of brackets ('[]') at the right side; if you had there something already, copy paste this between the brackets and keep only the outermost brackets.

You're looking for the toggle_comment command. (Edit > Comment > Toggle Comment)

By default, this command is mapped to:

• Ctrl+/ (On Windows and Linux)
• Command ?+/ (On Mac)

This command also takes a block argument, which allows you to use block comments instead of single lines (e.g. /* ... */ as opposed to // ... in JavaScript). By default, the following key combinations are mapped to toggle block comments:

• Ctrl+Shift+/ (On Windows and Linux)
• Command ?+Alt+/ (On Mac)

Ctrl-/ will insert // style commenting, for javascript, etc
Ctrl-/ will insert <!-- --> comments for HTML,
Ctrl-/ will insert # comments for Ruby,
..etc

But does not work perfectly on HTML <script> tags.

HTML <script> ..blah.. </script> tags:
Ctrl-/ twice (ie Ctrl-/Ctrl-/) will effectively comment out the line:

• The first Ctrl-/ adds // to the beginning of the line,
  which comments out the script tag, but adds "//" text to your webpage.
• The second Ctrl-/ then surrounds that in <!-- --> style comments, which accomplishes the task.

Ctrl--Shift-/ does not produce multi-line comments on HTML (or even single line comments), but does
add /* */ style multi-line comments in Javascript, text, and other file formats.

--

[I added as a new answer since I could not add comments.
I included this info because this is the info I was looking for, and this is the only related StackOverflow page from my search results.
I since discovered the / / trick for HTML script tags and decided to share this additional information, since it requires a slight variation of the usual catch-all (and reported above)
/ and Ctrl--Shift-/ method of commenting out one's code in sublime.]

In mac I did this

• type your comment and press command + D to select the text
• and then press Alt + Command + / to comment out the selected text.