nix-bitcoin/docs/faq.md

• Q: The clightning service is running but when I try to use it (f.e. by running lightning-cli getinfo as user operator) all I get is lightning-cli: Connecting to 'lightning-rpc': Connection refused.
  A: Check your clightning logs with journalctl -eu clightning. Do you see something like bitcoin-cli getblock ... false failed? Are you using pruned mode? That means that clightning hasn't seen all the blocks it needs to and it can't get that block because your node is pruned.
  If you're just setting up a new node you can systemctl stop clightning and wipe your /var/lib/clightning directory. Otherwise you need to reindex the Bitcoin node.

• Q: My disk space is getting low due to nix.
  A: run nix-collect-garbage -d

• Q: Where is sudo?
  A: After CVE-2021-3156, we've replaced sudo with OpenBSD's doas for users of the secure-node.nix template. It has greatly reduced complexity and is therefore less likely to be a source of severe vulnerabilities in the future.