kakoune connection breaks due changed TMPDIR inside nix-shell

[tripokey]

Issue description

kakoune fails to create new splits when run inside a nix-shell.

kakoune uses the TMPDIR environment variable when deciding where to create its session sockets and nix-shell changes TMPDIR rendering it unable to find the session socket to connect to after creating a new tmux split.

Steps to reproduce

$ tmux
$ nix-shell -p hello
$ kak

While in kakoune type :new and press .

Technical details

• System: 17.03.902.536d3cac2e (Gorilla)
• Nix version: nix-env (Nix) 1.11.8
• Nixpkgs version: "17.03.902.536d3cac2e"

[Mic92]

Workaround is to set TMPDIR to export TMPDIR=/run/user/$(id -u) in your shell rc. /tmp/ is currently not a tmpfs, which /run/user/<uid> is.

[Mic92]

Actually I don't know why they are different historically. Probably /run/user/ is better shielded against interference of other user.

[tripokey]

Thanks!

Considering that TMPDIR might differ for tmux and kakoune regardless of wether NixOS is used or not I filed an issue for this in the kakoune repository:
mawww/kakoune#1319