Tmux option `xterm-keys` does not enable control+arrows

inputrctmux

I cannot make tmux recognize Ctrl–Left-arrow sequence differently from just a left arrow, and the same for the right arrow too. In my ~/.inputrc, I have mapped these sequences (as issued by 2 different terminal emulators, namely putty and mobaxterm) to jump over words in command line:

"\eOD": backward-word
"\e[1;5D": backward-word

This works in an ssh session just fine, but both screen and tmux do not distinguish between arrows and control-arrows. Naturally, the recommended solution is to enable the option xterm-keys in tmux by adding the global option into ~/.tmux.conf, and there is direct evidence (besides the "thanks" comments to the above solution) that this works for other people. But for me, Ctrl–Left-arrow sends the same code, ESC D, as does Left-arrow.

I have confirmed that the option is indeed set by checking tmux options with

:show-window-options -g

and even set it just in case for the current window manually with

:set-window-option xterm-keys on

but all this to no avail. tmux reports version number 1.8 with tmux -V.

What else may I check to troubleshoot this problem?

Best Answer

You should use the -g (global) option in this line:

:set-window-option xterm-keys on

making it

:set-window-option -g xterm-keys on

The tmux manual is not very clear, saying of -g:

If -g is specified, the global session or window option is set.
With -a, and if the option expects a string, value is appended to
the existing setting. The -u flag unsets an option, so a session
inherits the option from the global options. It is not possible
to unset a global option.

The key part of this is session, which is the set of pseudo-terminals create when you start tmux.

Related Solutions

Shift-arrow not working in emacs within tmux

First, make sure your TERM is correct at each location:

xterm-something (e.g. xterm-256color) inside your local shell running in your iTerm2 window
xterm-something inside your shell after SSHing to the Linux system
This should be the same as whatever you are using locally in iTerm2, since SSH should be passing it along to the remote side (and, importantly, the remote side should not be blindly overriding the value in a shell initialization file).
screen-something (e.g. screen-256color) inside your shell running under tmux on the Linux system
You should always use a screen-based TERM inside tmux.

Having an xterm TERM immediately outside tmux will allow tmux to recognize the modified arrow keys, but it will not pass them through unless you also have its xterm-keys window option turned on. Put this in your ~/.tmux.conf on the Linux system:

set-window-option -g xterm-keys on

The sequences for the shifted keys should now make it through to Emacs, running inside tmux, across an SSH connection, inside an iTerm2 window.

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

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"

Best Answer

Related Solutions

Shift-arrow not working in emacs within tmux

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

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