'\" t
.\"     Title: lightning-pay
.\"    Author: [see the "AUTHOR" section]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: 05/23/2019
.\"    Manual: \ \&
.\"    Source: \ \&
.\"  Language: English
.\"
.TH "LIGHTNING\-PAY" "7" "05/23/2019" "\ \&" "\ \&"
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.\" * MAIN CONTENT STARTS HERE *
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.SH "NAME"
lightning-pay \- Command for sending a payment to a BOLT11 invoice
.SH "SYNOPSIS"
.sp
\fBpay\fR \fIbolt11\fR [\fImsatoshi\fR] [\fIlabel\fR] [\fIriskfactor\fR] [\fImaxfeepercent\fR] [\fIretry_for\fR] [\fImaxdelay\fR] [\fIexemptfee\fR]
.SH "DESCRIPTION"
.sp
The \fBpay\fR RPC command attempts to find a route to the given destination, and send the funds it asks for\&. If the \fIbolt11\fR does not contain an amount, \fImsatoshi\fR is required, otherwise if it is specified it must be \fInull\fR\&. \fImsatoshi\fR is in millisatoshi precision; it can be a whole number, or a whole number with suffix \fImsat\fR or \fIsat\fR, or a three decimal point number with suffix \fIsat\fR, or an 1 to 11 decimal point number suffixed by \fIbtc\fR\&.
.sp
The \fIlabel\fR field is used to attach a label to payments, and is returned in lightning\-listpays(7) and lightning\-listsendpays(7)\&. The \fIriskfactor\fR is described in detail in lightning\-getroute(7), and defaults to 10\&. The \fImaxfeepercent\fR limits the money paid in fees, and defaults to 0\&.5\&. The maxfeepercent\*(Aq is a percentage of the amount that is to be paid\&. The `exemptfee option can be used for tiny payments which would be dominated by the fee leveraged by forwarding nodes\&. Setting exemptfee allows the maxfeepercent check to be skipped on fees that are smaller than exemptfee (default: 5000 millisatoshi)\&.
.sp
The response will occur when the payment fails or succeeds\&. Once a payment has succeeded, calls to \fBpay\fR with the same \fIbolt11\fR will succeed immediately\&.
.sp
Until \fIretry_for\fR seconds passes (default: 60), the command will keep finding routes and retrying the payment\&. However, a payment may be delayed for up to maxdelay blocks by another node; clients should be prepared for this worst case\&.
.sp
When using \fIlightning\-cli\fR, you may skip optional parameters by using \fInull\fR\&. Alternatively, use \fB\-k\fR option to provide parameters by name\&.
.SH "RANDOMIZATION"
.sp
To protect user privacy, the payment algorithm performs some randomization\&.
.sp
.RS 4
.ie n \{\
\h'-04' 1.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  1." 4.2
.\}
Route Randomization
.RE
.sp
.RS 4
.ie n \{\
\h'-04' 2.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  2." 4.2
.\}
Shadow Route
.RE
.sp
Route randomization means the payment algorithm does not always use the lowest\-fee or shortest route\&. This prevents some highly\-connected node from learning all of the user payments by reducing their fees below the network average\&.
.sp
Shadow route means the payment algorithm will virtually extend the time delays along the route, making it appear to intermediate nodes that the route is longer than it actually is\&. This prevents intermediate nodes from reliably guessing their distance from the payee\&.
.sp
Route randomization will never exceed \fImaxfeepercent\fR of the payment\&. Route randomization and shadow routing will not take routes that would exceed \fImaxdelay\fR\&.
.SH "RETURN VALUE"
.sp
On success, this returns the \fIpayment_preimage\fR which hashes to the \fIpayment_hash\fR to prove that the payment was successful\&. It will also return, a \fIgetroute_tries\fR and a \fIsendpay_tries\fR statistics for the number of times it internally called \fBgetroute\fR and \fBsendpay\fR\&.
.sp
You can monitor the progress and retries of a payment using the lightning\-paystatus(7) command\&.
.sp
The following error codes may occur:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\-1\&. Catchall nonspecific error\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
201\&. Already paid with this
\fIhash\fR
using different amount or destination\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
203\&. Permanent failure at destination\&. The
\fIdata\fR
field of the error will be routing failure object\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
205\&. Unable to find a route\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
206\&. Route too expensive\&. Either the fee or the needed total locktime for the route exceeds your
\fImaxfeepercent\fR
or
\fImaxdelay\fR
settings, respectively\&. The
\fIdata\fR
field of the error will indicate the actual
\fIfee\fR
as well as the
\fIfeepercent\fR
percentage that the fee has of the destination payment amount\&. It will also indicate the actual
\fIdelay\fR
along the route\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
207\&. Invoice expired\&. Payment took too long before expiration, or already expired at the time you initiated payment\&. The
\fIdata\fR
field of the error indicates
\fInow\fR
(the current time) and
\fIexpiry\fR
(the invoice expiration) as UNIX epoch time in seconds\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
210\&. Payment timed out without a payment in progress\&.
.RE
.sp
Error codes 202 and 204 will only get reported at \fBsendpay\fR; in \fBpay\fR we will keep retrying if we would have gotten those errors\&.
.sp
A routing failure object has the fields below:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\fIerring_index\fR\&. The index of the node along the route that reported the error\&. 0 for the local node, 1 for the first hop, and so on\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\fIerring_node\fR\&. The hex string of the pubkey id of the node that reported the error\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\fIerring_channel\fR\&. The short channel ID of the channel that has the error, or
\fI0:0:0\fR
if the destination node raised the error\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\fIfailcode\fR\&. The failure code, as per BOLT #4\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\fIchannel_update\fR\&. The hex string of the
\fIchannel_update\fR
message received from the remote node\&. Only present if error is from the remote node and the
\fIfailcode\fR
has the UPDATE bit set, as per BOLT #4\&.
.RE
.sp
The \fIdata\fR field of errors will include statistics \fIgetroute_tries\fR and \fIsendpay_tries\fR\&. It will also contain a \fIfailures\fR field with detailed data about routing errors\&.
.SH "AUTHOR"
.sp
Rusty Russell <rusty@rustcorp\&.com\&.au> is mainly responsible\&.
.SH "SEE ALSO"
.sp
lightning\-listpays(7), lightning\-decodepay(7), lightning\-listinvoice(7), lightning\-delinvoice(7), lightning\-getroute(7), lightning\-invoice(7)\&.
.SH "RESOURCES"
.sp
Main web site: https://github\&.com/ElementsProject/lightning