[root@build0:~]# nix-store --add config
/nix/store/4vxmfvdj9fl5adw48y5sq5hnxqg25by2-config

[root@build0:~]# md5sum config
4eba0b5e06ac11bda2fe81107c6fd476  config

[root@build0:~]# md5sum /var/ssh-nix/config
4eba0b5e06ac11bda2fe81107c6fd476  /var/ssh-nix/config

[root@build0:~]# nix-store --add config
/nix/store/4vxmfvdj9fl5adw48y5sq5hnxqg25by2-config

[root@build0:~]# nix-store --add /var/ssh-nix/config
/nix/store/k5fxcd1k35z3naksjj8ylnz4dnadlfvg-config