added stuff

nyx/docs/notes/cheatsheet.md

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+# Cheat sheet
+
+## Show GC roots
+
+```sh
+nix-store --gc --print-roots | grep -v "<hostName>" | column -t | sort -k3 -k1
+```
+
+## List all packages
+
+```sh
+nix-store -q --requisites /run/current-system | cut -d- -f2- | sort | uniq
+```
+
+You can add a `wc -l` at the end of the above command, but that will not be an accurate representation of
+your package count, as the same package can be repeated with different versions.
+
+## Find biggest packages
+
+```sh
+nix path-info -hsr /run/current-system/ | sort -hrk2 | head -n10
+```
+
+## Find biggest closures (packages including dependencies)
+
+```sh
+nix path-info -hSr /run/current-system/ | sort -hrk2 | head -n10
+```
+
+## Show package dependencies as tree
+
+> Assuming `hello` is in PATH
+
+```sh
+nix-store -q --tree $(realpath $(which hello))
+```
+
+## Show package dependencies including size
+
+```sh
+nix path-info -hSr nixpkgs#hello
+```
+
+## Show the things that will change on reboot
+
+```sh
+diff <(nix-store -qR /run/current-system) <(nix-store -qR  /run/booted-system)
+```