Channel names with `.` or `-` don't work with nix-env -iA attribute paths or don't work with nix-channel --remove

[CMCDragonkai]

When you create a channel with . or - in its name like: nix-channel --add https://nixos.org/channels/nixos-17.03-small nixos-17.03-small. And then you try to use it with an attribute path like nix-env -iA 'nixos-17.03-small.hello, nix-env complains that it cannot find the attribute path. But if you instead give it a name like A, then it will work!

This is happening on 1.11.15.

[CMCDragonkai]

This error also affects deletion of channels like nix-channel --remove nixos-17.03-small will just not work.

But removal problem is caused by the - character as well.

[CMCDragonkai]

This error is the same error as described here: #1067

[CMCDragonkai]

To resolve this, channel names should not be allowed to have ., while nix-channel needs to be fixed to allow - in their names.

[stale]

I marked this as stale due to inactivity. → More info

[cdepillabout]

you try to use it with an attribute path like nix-env -iA 'nixos-17.03-small.hello, nix-env complains that it cannot find the attribute path

You can work around this by quoting the attribute name:

$ nix-channel --add https://nixos.org/channels/nixos-20.09-small nixos-20.09-small
$ nix-channel --list
nixos-20.09-small https://nixos.org/channels/nixos-20.09-small
$ nix-channel --update
$ nix-env -iA '"nixos-20.09-small".python3Packages.xdot'
installing 'python3.8-xdot-1.1'
...

This works because channels are given their own attribute names. Similarly, you can create an attribute set with names with periods:

$ nix repl
> { "attribute.with.dots" = 3; }
{ "attribute.with.dots" = 3; }

This error also affects deletion of channels like nix-channel --remove nixos-17.03-small will just not work.

This doesn't appear to be the case anymore.

$ nix-channel --remove "nixos-20.09-small"
$ nix-channel --list

This is on nix-2.3.10.

[cdepillabout]

This error also affects deletion of channels like nix-channel --remove nixos-17.03-small will just not work.
This doesn't appear to be the case anymore.

Actually, I just saw #1067, and this does still seem to be a bug.

Despite nix-channel --remove working correctly, the channel is still leftover in ~/.nix-defexpr/channels/:

$ ls -lah ~/.nix-defexpr/channels/
total 22M
dr-xr-xr-x     2 root root   4.0K Jan  1  1970 .
drwxrwxr-t 10117 root nixbld  22M Feb 16 09:35 ..
lrwxrwxrwx     1 root root     60 Jan  1  1970 manifest.nix -> /nix/store/xwxv7fylj1csazawsxznvfx0cfjbh6ng-env-manifest.nix
lrwxrwxrwx     1 root root    102 Jan  1  1970 nixos-20.09-small -> /nix/store/8s7yakyq8vxwbf1n2vs3wa075fb1dkmc-nixos-20.09-small-20.09.3152.08327493801/nixos-20.09-small

Note that this doesn't happen if I don't have . in the channel name:

$ nix-channel --add https://nixos.org/channels/nixos-20.09-small nixos2009small
$ nix-channel --update
$ nix-channel --list
nixos2009small https://nixos.org/channels/nixos-20.09-small
$ nix-env -iA nixos2009small.python3Packages.xdot
installing 'python3.8-xdot-1.1'
...
$ nix-channel --remove nixos2009small
uninstalling 'nixos2009small-20.09.3152.08327493801'
building '/nix/store/c8z96qkdlkp9r8phgw4z6nd7bw8y0nnd-user-environment.drv'...
created 2 symlinks in user environment
$ nix-channel --list
$ ls -lah ~/.nix-defexpr/channels/
total 22M
dr-xr-xr-x     2 root root   4.0K Jan  1  1970 .
drwxrwxr-t 10117 root nixbld  22M Feb 16 09:35 ..
lrwxrwxrwx     1 root root     60 Jan  1  1970 manifest.nix -> /nix/store/xwxv7fylj1csazawsxznvfx0cfjbh6ng-env-manifest.nix