nix run doesn't set IN_NIX_SHELL

[ElvishJerricco]

Title. My shell prompt is set to look different when IN_NIX_SHELL is set, and I have nix-shell aliased to include my prompt. Since nix run doesn't set IN_NIX_SHELL, I often have a hard time remembering if my shell is a nix run or not.

[edolstra]

It's not clear whether it should set IN_NIX_SHELL, because nix run serves a different purpose than nix-shell (it doesn't provide a development environment).

[ElvishJerricco]

@edolstra I guess that just depends on the intended semantics of IN_NIX_SHELL, and whether we plan to eventually have a mode of nix run for development environments.

Regardless, at least something should be set.

[ElvishJerricco]

I've since found that $SHLVL is more appropriate for what I was using $IN_NIX_SHELL for. I'll close this, as it doesn't seem to be desired.

[giodamelio]

Just running this into myself, it would be nice to have some way to tell.

[ElvishJerricco]

@giodamelio Does SHLVL help? I found it useful for more than just nix run; now I know any time I'm in a nested shell, not just a nix run.

[giodamelio]

That won't really work for what I am doing. I want to simply display a thing in my prompt when I am in a Nix shell, not when I am in a nested shell. For example the SHLVL gets incremented when I am in a tmux session (which makes sense), but it doesn't have anything to do with Nix specifically.

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On Wed, Sep 12, 2018, 9:45 AM Will Fancher ***@***.***> wrote: @giodamelio <https://github.com/giodamelio> Does SHLVL help? I found it useful for more than just nix run; now I know *any* time I'm in a nested shell, not just a nix run. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#2020 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAa9LlDlK6l-0cr20NQDvw2bSe6LgVZuks5uaToMgaJpZM4S92cv> .

[fgaz]

I ran into this too. I have different prompts for different kinds of subshells, but I have no way to tell the difference from nix run and a simple subshell

[timor]

Couldn't nix run set a different variable, let's say IN_NIX_RUN, or have it's own nesting counter?

[pinpox]

Couldn't nix run set a different variable, let's say IN_NIX_RUN, or have it's own nesting counter?

+1 for this. I'd like to have some way to display it in the prompt e.g. when entering a shell with nix shell 'nixpkgs#hello'
to fix this starship/starship#2950

[fgaz]

Related: #3862