Remapping <Esc> in MacVim angers Vim itself

Question

I have the following line in my .vimrc:

nnoremap <Esc> :noh<Cr>

This works fine in MacVim. Whenever I open Vim itself, its "command bar" starts off with:

.2c

For what it's worth, when enter to execute the command, Vim complains with E16: Invalid range.

It's a minor annoyance, but how do I resolve this issue?

Answer 1

Mapping Esc is always a little tricky and generally inviting this kind of trouble, even though it shouldn't happen.

The "canonical" method for your mapping is:

nnoremap <silent> <C-l> :nohlsearch<CR><C-l>

That way Ctrl+L (which normally redraws your screen) will stop highlighting and redraw the screen.

---

I think I've found out what happens, but I still have no solution. I assumed Vim received a string containing an <ESC> and "2c", so I used the following mapping to make it visible:

nnoremap <Esc> :"

It resulted in the following prompt on startup:

:"[>0;261;0c

Which means something sent <ESC>[>0;261;0c on startup. Now looking up the original xterm control sequences, we find that:

ESC [         Control Sequence Introducer (CSI is 0x9b)

and

CSI > P s c

Send Device Attributes (Secondary DA).

P s = 0 or omitted → request the terminal’s identification code. The response depends on the decTerminalID resource setting. It should apply only to VT220 and up, but xterm extends this to VT100.

→ CSI > P p ; P v ; P c c

where P p denotes the terminal type

P p = 0 → ‘‘VT100’’.
P p = 1 → ‘‘VT220’’.

and P v is the firmware version (for xterm, this was originally the XFree86 patch number, starting with 95). In a DEC terminal, P c indicates the ROM cartridge registration number and is always zero.

So in my case something sends CSI > with P p = 0 (→ terminal type VT100), P v = 261 (→ my xterm version), and P c = 0.

Still I have no idea where it comes from or how to stop it. My best guess is that some information exchange between the terminal and Vim fails and something is bugged up.

Answer 2

The problem is for some terminal vim receives [>0;261;0c that way. And the last "c" makes vim start painful, but I have found easy trick for skipping first "c" at startup:

nnoremap c :nunmap c<Cr>