I'm on the unstable nix channel:
# nix-channel --list
nixos https://nixos.org/channels/nixos-unstable
# nix-channel --update
downloading Nix expressions from ‘https://nixos.org/releases/nixos/unstable/nixos-16.09pre78848.9549257//nixexprs.tar.xz’...
downloading ‘https://nixos.org/releases/nixos/unstable/nixos-16.09pre78848.9549257//nixexprs.tar.xz’... [ [6192/6921 KiB, 6143.1 KiB/s]
unpacking channels...
For some reason, command-not-found doesn't work:
$ command-not-found
/home/fabian command-not-found
DBI connect('dbname=/nix/var/nix/profiles/per-user/root/channels/nixos/programs.sqlite','',...) failed: unable to open database file at /run/current-system/sw/bin/command-not-found line 13.
cannot open database `/nix/var/nix/profiles/per-user/root/channels/nixos/programs.sqlite' at /run/current-system/sw/bin/command-not-found line 13.
Indeed, /nix/var/nix/profiles/per-user/root/channels/nixos/programs.sqlite doesn't exist. What could be the reason for this?
Apparently it's removed in the most recent channels/nixos builds and awaiting a replacement - refs (1) (2)