bug: Broken shell option for tmux on macOS

[shivaraj-bh]

Are you following the right branch?

• My Nixpkgs and Home Manager versions are in sync

Is there an existing issue for this?

• I have searched the existing issues

Issue description

Even after setting shell = lib.getExe pkgs.zsh;, tmux on macOS starts with sh. Upon inspection with tmux show-options -g, I found the culprit to be the default-command setting:

default-command "/nix/store/b8gwfk11yb0y4f77jhfaqy04w5hxgwmy-reattach-to-user-namespace-2.9/bin/reattach-to-user-namespace -l /bin/sh"
default-shell /nix/store/g1flsbrma4f0zq8gaxc2w377r77mqlv7-zsh-5.9/bin/zsh

From https://man7.org/linux/man-pages/man1/tmux.1.html, you can see that default-command overrides default-shell.

Maintainer CC

No response

System information

- system: `"aarch64-darwin"`
 - host os: `Darwin 23.6.0, macOS 14.6.1`
 - multi-user?: `yes`
 - sandbox: `no`
 - version: `nix-env (Nix) 2.24.10`
 - nixpkgs: `/nix/store/4bl6b8qjy6agsgsa8xhz1lc3jaxp3iwf-source`

[suasuasuasuasua]

The sh bug has been broken for me for months. Haven't used tmux on macOS in forever

[tedbyron]

Issue for me was the sensibleOnTop option defaulting to true somehow even though the source has default as false.

Had to add a line in my config with sensibleOnTop = false;, before I did that it was still adding the following block to my tmux config:

# ============================================= #
# Start with defaults from the Sensible plugin  #
# --------------------------------------------- #
run-shell ${pkgs.tmuxPlugins.sensible.rtp}
# ============================================= #

Which is what changes default-command. Same issue also reported in tmux-sensible tmux-plugins/tmux-sensible#75 but that repo isn't maintained