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Instructions for the Command-Line Interface

### The Basics Monero works a little differently to what you may have become accustomed to from other @cryptocurrencies. In the case of a digital currency like Bitcoin and its many derivatives merchant payment systems will usually create a new recipient @address for each payment or user. However, because Monero has @stealth-addresses there is no need to have separate recipient addresses for each payment or user, and a single @account address can be published. Instead, when receiving payments a merchant will provide the person paying with a "payment ID". A @payment-ID is a hexadecimal string that is 64 characters long, and is normally randomly created by the merchant. An example of a payment ID is: ``` 666c75666679706f6e7920697320746865206265737420706f6e792065766572 ``` ### Checking for a Payment in monero-wallet-cli If you want to check for a payment using monero-wallet-cli you can use the "payments" command followed by the payment ID or payment IDs you want to check. For example: ``` [wallet 49VNLa]: payments 666c75666679706f6e7920697320746865206265737420706f6e792065766572 payment transaction height amount unlock time 666c75666679706f6e79206973207 7ba4cd810c9b4096869849458181e98e 441942 30.00000 0 [wallet 49VNLa]: █ ``` If you need to check for payments programmatically, then details follow the next section. ### Receiving a Payment Step-by-Step * Generate a random 64 character hexadecimal string for the payment * Communicate the payment ID and Monero address to the individual who is making payment * Check for the payment using the "payments" command in monero-wallet-cli ### Checking for a Payment Programmatically In order to check for a payment programmatically you can use the get_payments or get_bulk_payments JSON RPC API calls. *get_payments*: this requires a payment_id parameter with a single payment ID. *get_bulk_payments*: this is the preferred method, and requires two parameters, payment_ids - a JSON array of payment IDs - and an optional min_block_height - the block height to scan from. An example of returned data is as follows: ``` [ monero->~ ]$ curl -X POST http://127.0.0.1:18500/json_rpc -d '{"jsonrpc":"2.0","method":"get_bulk_payments","id":"test", "params":{"payment_ids": ["666c75666679706f6e7920697320746865206265737420706f6e792065766572"]}}' -H "Content-Type: application/json" { "id": "test", "jsonrpc": "2.0", "result": { "payments": [{ "amount": 30000000000000, "block_height": 441942, "payment_id": "666c75666679706f6e7920697320746865206265737420706f6e792065766572", "tx_hash": "7ba4cd810c9b4096869849458181e98e18b6474ab66415de0f4ccf7ab1162fdf", "unlock_time": 0 }] } } ``` It is important to note that the amounts returned are in base Monero units and not in the display units normally used in end-user applications. Also, since a transaction will typically have multiple outputs that add up to the total required for the payment, the amounts should be grouped by the tx_hash or the payment_id and added together. Additionally, as multiple outputs can have the same amount, it is imperative not to try and filter out the returned data from a single get_bulk_payments call. Before scanning for payments it is useful to check against the daemon RPC API (the get_info RPC call) to see if additional blocks have been received. Typically you would want to then scan only from that received block on by specifying it as the min_block_height to get_bulk_payments. ### Programatically Scanning for Payments * Get the current block height from the daemon, only proceed if it has increased since our last scan * Call the get_bulk_payments RPC API call with our last scanned height and the list of all payment IDs in our system * Store the current block height as our last scanned height * Remove duplicates based on transaction hashes we have already received and processed