lightning-close – Command for closing channels with direct peers¶
close id [unilateraltimeout] [destination] [fee_negotiation_step]
The close RPC command attempts to close the channel cooperatively with the peer, or unilaterally after unilateraltimeout, and the to-local output will be sent to the address specified in destination.
If the given id is a peer ID (66 hex digits as a string), then it applies to the active channel of the direct peer corresponding to the given peer ID. If the given id is a channel ID (64 hex digits as a string, or the short channel ID blockheight:txindex:outindex form), then it applies to that channel.
If unilateraltimeout is not zero, the close command will unilaterally close the channel when that number of seconds is reached. If unilateraltimeout is zero, then the close command will wait indefinitely until the peer is online and can negotiate a mutual close. The default is 2 days (172800 seconds).
The destination can be of any Bitcoin accepted type, including bech32. If it isn’t specified, the default is a c-lightning wallet address.
The fee_negotiation_step parameter controls how closing fee negotiation is performed assuming the peer proposes a fee that is different than our estimate. On every negotiation step we must give up some amount from our proposal towards the peer’s proposal. This parameter can be an integer in which case it is interpreted as number of satoshis to step at a time. Or it can be an integer followed by “%” to designate a percentage of the interval to give up. A few examples, assuming the peer proposes a closing fee of 3000 satoshi and our estimate shows it must be 4000:
- “10”: our next proposal will be 4000-10=3990.
- “10%”: our next proposal will be 4000-(10% of (4000-3000))=3900.
- “1”: our next proposal will be 3999. This is the most extreme case when we insist on our fee as much as possible.
- “100%”: our next proposal will be 3000. This is the most relaxed case when we quickly accept the peer’s proposal. The default is “50%”.
The peer needs to be live and connected in order to negotiate a mutual close. The default of unilaterally closing after 48 hours is usually a reasonable indication that you can no longer contact the peer.
Prior to 0.7.2, close took two parameters: force and timeout. timeout was the number of seconds before force took effect (default, 30), and force determined whether the result was a unilateral close or an RPC error (default). Even after the timeout, the channel would be closed if the peer reconnected.
On success, an object with fields tx and txid containing the closing transaction are returned. It will also have a field type which is either the JSON string mutual or the JSON string unilateral. A mutual close means that we could negotiate a close with the peer, while a unilateral close means that the force flag was set and we had to close the channel without waiting for the counterparty.
A unilateral close may still occur at any time if the peer did not behave correctly during the close negotiation.
Unilateral closes will return your funds after a delay. The delay will vary based on the peer to_self_delay setting, not your own setting.