In command mode make delete not act like backspace

Question

In command mode there is no delete from cursor to the end of line (like CTRL-k in bash). So to delete a long line of trailing text, I press and hold delete, which works fine until it runs out of characters to the right of cursor, and which points it starts steam rolling over the part of the command I wish to keep (i.e. starts backspacing).

Is there anyway to turn off this unusual behaviour, as confirmed by the help:

<Del>       Delete the character under the cursor (at end of line:
            character before the cursor).

PS I know about CTRL-F to see the cmdline, but sometimes I wish to quickly change the end of an existing command.

Answer 1

To change the behavior of <Del> so that it only deletes the character under the cursor and doesn't behave like backspace when at the end of the line, you can use the following mapping:

cnoremap <expr> <Del> getcmdpos() <= strlen(getcmdline()) ? "\<Del>" : ""

See @D.BenKnoble's answer for a solution to deleting until the end of the line (similar to what <C-K> does in bash and other readline-based programs.)

Answer 2

You can use the following function:

function KillEnd()
  let l:cmd = getcmdline()
  let l:pos = getcmdpos()
  let l:newcmd = strpart(l:cmd, 0, l:pos - 1)
  return l:newcmd
endfunction

To use it on the command line, you need to do (I choose <C-x> arbitrarily since it wasn't used for anything else, and reminds me of X in normal mode):

cnoremap <C-x> <C-\>eKillEnd()<CR>

See :help c_CTRL-\_e for details on the mapping; the <C-\>e sequence uses an expression to replace the entire command line.

The function returns a substring of the command line based on the cursor position.

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If you wanted a one-liner:

cnoremap <C-x> <C-\>estrpart(getcmdline(), 0, getcmdpos() - 1)<CR>