Problem using Ctrl+Arrow keys in Vim when using Byobu with tmux

byobutmuxvim

In Vim, I had set the Ctrl+Arrow keys to skip words. This works just fine when running Vim inside the gnome-terminal.

However, when using byobu (tmux), it shows weird behavior : it deletes everything after the cursor.

For reference, these are my vim settings:

:inoremap <C-Left> <C-\><C-O>b
:inoremap <C-Right> <C-\><C-O>w

Best Answer

The problem is twofold. First, tmux by default converts the control-arrow keys from one type of escape sequence to another. So special keys such as controlleft are sent to vim without the modifier, e.g., left. If you use cat -v to see the different escape sequences, you might see something like this

^[OD

versus this (outside tmux):

^[[1;5D

The line

set-window-option -g xterm-keys on

fixes that aspect. The other part is that tmux by default uses the terminal description for screen. That terminal description does not describe the control-arrow keys. These entries from the terminal database would be the most appropriate for VTE (gnome-terminal):

There are others, such as

which would be automatically selected when running in screen if the corresponding TERM outside were vte, vte-256color, etc. tmux does not do this automatic-selection; you have to modify its configuration file.

By the way, there is no "screen.xterm" entry because it would interfere with some usages of screen. There is no conflict with TERM=xterm-new.

If you have a default (minimal) terminal database such as ncurses-base in Debian, you might not have those. More common would be xterm-256color, which is close enough to use with vim and tmux.

For example, if I add this to my .tmux.conf file, it behaves as you expect in vim:

set -g default-terminal "xterm-256color"

Related Solutions

Why is Vim eating up Ctrl when used with Ctrl+v and how to fix it

This is actually your terminal doing something weird, not Vim. Terminals have two sets of control sequences associated with cursor keys, for historical reasons: one for full-screen applications, often called “application cursor keys mode”, and one for read-eval-print applications (e.g. shells).

In the old days, read-eval-print applications didn't have any line-editing features, and it was intended that the terminal, or the OS terminal driver, would eventually become more sophisticated. So the terminal sent control sequences intended for the terminal driver. Somehow the Unix terminal drivers never gained decent line-editing features; these were added to applications instead (e.g. through the readline library).

Your terminal is sending ␛OD for Ctrl+Left in line edition cursor keys mode, and ␛[D in application cursor keys mode. You have two options:

Configure your terminal not to make a difference between the two modes. How to do this is entirely dependent on your terminal emulator.
Live with it. Since any given application always sets the terminal in the same mode, just configure its key bindings according to the mode it uses.

The gnome-terminal ANSI escape sequence for “CTRL + arrow/s”

Gnome-terminal (more properly VTE) imitates some version of xterm's escape sequences. How closely it does this, depends on the version of VTE.

The relevant xterm documentation is in the PC-Style Function Keys section of XTerm Control Sequences.

What you are looking for is a string like \e[1;5D (for control left-arrow), where the 5 denotes the control modifier.

In ncurses, you can see these strings using infocmp -x, as the values for kUP5, kDN5, kLFT5 and kRIT5. For example:

    kDN5=\E[1;5B,
    kLFT5=\E[1;5D,
    kRIT5=\E[1;5C,        
    kUP5=\E[1;5A,

Best Answer

Related Solutions

Why is Vim eating up Ctrl when used with Ctrl+v and how to fix it

The gnome-terminal ANSI escape sequence for “CTRL + arrow/s”

Related Question