NixOS - Running binaries in session file requires absolute paths?

[xfzv]

On NixOS 25.05, I'm trying to use the following session.conf:

new_tab 1
launch zsh -i -c 'y'

new_tab 2
launch zsh -i -c 'v'

with:

% kitty --session /path/to/session.conf

But this doesn't work. Kitty just opens a blank shell in /path/to/session.conf.

% which zsh
/etc/profiles/per-user/xfzv/bin/zsh

If I use zsh absolute path, then it works as expected:

new_tab 1
- launch zsh -i -c 'y'
+ launch /etc/profiles/per-user/xfzv/bin/zsh -i -c 'y'

new_tab 2
- launch zsh -i -c 'v'
+ launch /etc/profiles/per-user/xfzv/bin/zsh -i -c 'v'

I eventually found exe_search_path option in the docs.

Based on the option description, I guess I shouldn't have to add it to kitty.conf since /etc/profiles/per-user/xfzv/bin is in my $PATH:

% echo $PATH
/run/wrappers/bin:/home/xfzv/.nix-profile/bin:/nix/profile/bin:/home/xfzv/.local/state/nix/profile/bin:/etc/profiles/per-user/xfzv/bin:/nix/var/nix/profiles/default/bin:/run/current-system/sw/bin

It's not the case for my root user so I tried it just to make sure, but it doesn't make any difference:

{
  config,
  ...
}:
programs.kitty.settings = {
    exe_search_path = "+/etc/profiles/per-user/${config.home.username}/bin:/run/current-system/sw/bin";
}

Am I really supposed to use full paths in session.conf i.e. launch /etc/profiles/per-user/xfzv/bin/zsh instead of launch zsh in this case?

On non-Nix OS distros, launch zsh works just fine for me, I don't have to use e.g. launch /usr/bin/zsh.

[kovidgoyal]

https://sw.kovidgoyal.net/kitty/faq/#things-behave-differently-when-running-kitty-from-system-launcher-vs-from-another-terminal

[xfzv]

Thanks for the reply and the link.

Not sure why but now it's working just fine with launch zsh after rebooting the system and without adding

exe_search_path = "+/etc/profiles/per-user/${config.home.username}/bin:/run/current-system/sw/bin";

Turns out kitty sees /etc/profiles/per-user/xfzv/bin just fine by default. With show_kitty_env_vars mapped to f1:

PATH=/run/wrappers/bin:/home/xfzv/.nix-profile/bin:/nix/profile/bin:/home/xfzv/.local/state/nix/profile/bin:/etc/profiles/per-user/xfzv/bin:/nix/var/nix/profiles/default/bin:/run/current-system/sw/bin:/nix/store/ch2v48p4ip1dh12iw265sxnj40jh38xc-kitty-0.42.1/bin:/nix/store/w9393s0xnbdy4v0dqlb1i5iv305bdnz9-imagemagick-7.1.1-47/bin:/nix/store/c4ibx1x2y2xn21zij6nnpcmnrclp58wq-ncurses-6.5-dev/bin

Mapping kitty --session /path/to/session.conf to a shortcuts in Plasma settings works fine too.