agam@ubuntu-s-2vcpu-4gb-sfo3-01:~$ nix search emacs
warning: using cached results; pass '-u' to update the cache
...
* nixpkgs.emacs (emacs)
The extensible, customizable GNU text editor
* nixpkgs.emacs-nox (emacs-nox)
The extensible, customizable GNU text editor
...
* nixpkgs.emacs26 (emacs)
The extensible, customizable GNU text editor
...
agam@ubuntu-s-2vcpu-4gb-sfo3-01:~$ nix-env -i emacs26-nox
error: selector 'emacs26-nox' matches no derivations
agam@ubuntu-s-2vcpu-4gb-sfo3-01:~$ nix-env -i nixpkgs.emacs26-nox
error: selector 'nixpkgs.emacs26-nox' matches no derivations
agam@ubuntu-s-2vcpu-4gb-sfo3-01:~$ nix-env -i emacs-nox
installing 'emacs-nox-26.3'
these paths will be fetched (42.60 MiB download, 152.27 MiB unpacked):
/nix/store/14h22b5xsm4sfy7k2agxyglq748izvrf-gettext-0.20.1
/nix/store/6zlr5r85x5j8b9q898ina195brl8zdg6-emacs-26.3
copying path '/nix/store/14h22b5xsm4sfy7k2agxyglq748izvrf-gettext-0.20.1' from 'https://cache.nixos.org'...
copying path '/nix/store/6zlr5r85x5j8b9q898ina195brl8zdg6-emacs-26.3' from 'https://cache.nixos.org'...
building '/nix/store/776qzjq6vfkibglvfdisy0mcdx71wk54-user-environment.drv'...
created 68 symlinks in user environment
