how does ctrl+backspace work?

[simonLeary42]

I notice that when the "complete" menu is open, and I've hovered over an item using arrow keys, ctrl+backspace will delete that item from my input line. In other times, ctrl+backspace deletes the entire input line, and in others, it deletes a seemingly-arbitrary suffix from my input line. Is this behavior documented?

[akinomyoga]

It depends on what your terminal actually sends when you press Control+BackSpace. It largely depends on the terminal, as described in §3.1.1. Please read §3.1.1. Some terminals send C-h, some send C-?, some send C-BS (using the advanced keyboard protocol), some send C-w, and some send C-_. To check the code that your terminal sends, you can check the result of the following commands:

$ ble/debug/keylog#start
$       # <-- Please press Control+BackSpace here.
$ ble/debug/keylog#end

If your terminal sends C-BS, it performs delete-backward-cword as listed in §4.4. If there is a selected region (the text region highlighted for some reason), it deletes the selected region. When menu-complete is active (i.e., when you hover over an item in the menu), the temporarily inserted item on the command line is the selected region, so C-BS will delete the inserted item. Otherwise, it deletes the cword as in the widget name. The cword means a consecutive sequence of letters (a-zA-Z), digits (0-9), and underscores (_), or a sequence of other non-space characters.