Tmux, Iterm2 And Meta Keys

In September, someone posted on reddit about not being able to get his Tmux configuration work when SSHing into Ubuntu 10.04 from a Mac running iTerm2.

The source of the problem is iTerm2 sending \e[1;9A - \e[1;9D for ⌥ + arrow keys. I asked @gnachman why iTerm2 sends \e[1;9A - \e[1;9D and not \e[1;3A - \e[1;3D and he answered 9 was inherited from the old iTerm (see the conversation on Twitter).

To complicate things further, tmux up to version 1.8 used to remap \e[1;9A - \e[1;9D to \e[\e[A - \e[\e[D. Then tmux 1.9 and 1.9a stopped doing so while tmux master branch does it again after commit 193b6bcf36dda3754c99beb0dcc3dfdfceebdb09.

From there you have several options:

• make iTerm2 send \e[1;3A - \e[1;3D by remapping keys in your profile

• make iTerm2 send \e[1;3A - \e[1;3D by running iTerm2 nightly starting from Build 2.9.20140911 and using the new advanced “Treat Option as Meta in escape codes send by typing arrow keys” option

• let iTerm2 send \e[1;9A - \e[1;9D and let tmux know about kUP3, kDN3, kRIT3 and kLFT3 values

• let iTerm2 send \e[1;9A - \e[1;9D and run tmux HEAD e.g. by installing it with brew install --HEAD tmux

Hope that helps!