Shortcut to comment out a block of code with sublime text

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)

The shortcut to comment out or uncomment the selected text or current line:

• Windows: Ctrl+/
• Mac: Command ⌘+/
• Linux: Ctrl+Shift+/

Alternatively, use the menu: Edit > Comment

For the block comment you may want to use:

• Windows: Ctrl+Shift+/
• Mac: Command ⌘+Option/Alt+/