Preserve system bash prompt and configuration for non-pure devshells

[mayl]

I have an interactive bash prompt which is configured to my liking - starship.rs, fzf integration, ~~git aliases~~, z-lua, etc.

With a normal nixpkgs.mkShell I can enter a project shell without --pure and keep my system settings with me. However, devshell seems to override all these. I want access to my bash configuration and tools when working on a project, but it wouldn't be appropriate to burden my devshell with them since they are strictly speaking not project dependencies.

Is there a way to get devshell mirror the behavior of nixpkgs.mkShell when run without the --pure flag?

Edit: I spoke a bit too soon, looks like git aliases actually do persist as expected. The other comments still seem valid however.

[zimbatm]

Related issue https://github.com/numtide/devshell/issues/26

How are you loading the environment. Using nix-shell?

[mayl]

It's a little complicated, there is some more context here.

As a brief summary, I'm building my devshell as part of a nixos-generators vagrant-virtualbox machine for offline use. I've been using writeShellScriptBin just to give my devshell a memorable name and adding that to environment.systemPackages. I run that script to enter the devshell environment. I'm certainly not wedded to this approach if something better is available, but I do need a way to build nix-shell environments ahead of time and then use them in an offline environment and prefer to do it in a declarative way which is compatible with nixos-generators

[blaggacao]

I'll try to figure out a solution tomorrow. This also annoys me (using nix develop / zsh). #26 has a pending fix for review, which lead me to believe the solution for this issue here can't be far away, either.

• MANPATH handling → #125 ◆ #124

• PATH handling → #123 ◆ #26

• Shell completion → ◆ #128

• History (ro)

• ~~Prompt~~ (devshell has actually a very good default)

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Regardless of how the devshell would be invoked, for CI we could detect either a CI=true (most CIs) or a PURE=true and switch to pure eval, there.

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Reading again through https://blog.flowblok.id.au/2013-02/shell-startup-scripts.html ...

The good thing is from a devshell perspective we don't need to care about login shells altogether. We can also safely assume that any non-interactive shell is meant to be pure (or we can establish that restriction). So we are left with the interactive/non-login shell path on which we need o overlay the devshell enviroent. As if the path had a final ./devshellrc that was hit before enter the running state. (That's in a way what devshell does).

[mayl]

FWIW, my preference would still be to not have devshell enforce a particular prompt. For instance, I use starship for my prompt which among other things has support for nix-shell.