pinentry-curses doesn't provide pinentry-curses in PATH, when installed with nix-env

[jumper149]

Describe the bug
After installing pinentry-curses with nix-env -iA nixpkgs.pinentry-curses the actual derivation that is installed is nixpkgs.pinentry.

To Reproduce

nix-env -iA pinentry-curses
ls -l ~/.nix-profile/bin/pinentry*

this will only list pinentry and not pinentry-curses.

Expected behavior
After nix-env -iA nixpkgs.pinentry-curses both pinentry and pinentry-curses are in path.

I'm not sure what the package pinentry should provide. Maybe everything from pinentry-curses, pinentry-gnome, ...?

Additional context
I noticed a problem when using gpg on the tty. It will try to use pinentry-curses, but won't find it and say something like: No pinentry

Metadata
nix-shell -p nix-info --run "nix-info -m":

 - system: `"x86_64-linux"`
 - host os: `Linux 5.4.58, NixOS, 20.03.2806.cb1996818ed (Markhor)`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.3.6`
 - channels(root): `"nixos-20.03.2806.cb1996818ed"`
 - channels(jumper): `"nixpkgs-20.09pre239139.a19e16756b6"`
 - nixpkgs: `/home/jumper/.nix-defexpr/channels/nixpkgs`

Maintainer information (I hope I got this right ^^):

# a list of nixpkgs attributes affected by the problem
attribute:
pkgs.pinentry
pkgs.pinentry-curses
# a list of nixos modules affected by the problem
module:

[jumper149]

Regarding the troubles with gpg:

I fixed it (even when using the regular nixpkgs.pinentry) by pointing the gpg-agent to the executable:
https://github.com/jumper149/dotfiles/blob/5d37bbced96c3f67ad8eb0e72c3d8327228d728e/.gnupg/gpg-agent.conf#L3

You can add pinentry-program /home/username/.nix-profile/bin/pinentry to ~/.gnupg/gpg-agent.conf

[matthewbauer]

This is from the way we use multiple outputs with pinentry. It's not a great situation IMO, but probably easier to just manually install the outputs here.

You can try adding meta.outputsToInstall = [ "out" ] ++ enabledFlavors to the derivation. If that fixes the issue, you open a PR.

[jonringer]

you can take look at #92084 , the "pinentry flavors" make it awkward to do a switch on which one you configured.

but the pinentry-curses package does contain both versions of the executable, on unstable and release channels:

$ nix-build -A pinentry.curses
... 
/nix/store/dg815gv4rl62bc0b66ghvddp8vqxvn30-pinentry-1.1.0-curses
$ ls ./result-curses/bin/
pinentry  pinentry-curses

[doronbehar]

The core issue IMO is: #65325 + NixOS/nix#3538 .

[flokli]

As explained by @doronbehar, the issue here is nix-env -iA not properly installing things from different outputs: NixOS/nix#3538

[flokli]

I closed this one, as there's a more generic tracking bug in Nixpkgs at #65325, in addition to the upstream Nix bug.