I dislike running out of HDD and then having to run `nix-collect-garbage` in the middle of hacking, but ok.
@jonn If you are using direnv, you can go through old projects and delete environments for those. Sadly, there are no good ways to manage garbage in NixOS, alas it's scriptable.
```
nix-store --gc --print-roots | grep '.direnv' | awk '{ "nix-store --query --size \""$3"\"" |& getline size; printf("%sMB\t %s -> %s \n", size / 1000000, $1, $3 ) }' | sort -h
```
