Basic commands to interact with the Bitcoin Core RPC console

6 min readJun 26, 2019

In this article we will explore using a fully synced Bitcoin Core node to run commands in the bitcoin-qt console. If you don’t yet have Bitcoin Core installed on your computer, you can download it here.

Be aware that Bitcoin Core has increasing minimum space requirements (currently ~250gb), bandwidth requirements, and will need to resync if offline for any period of time. See full costs and warnings for more info.

Bitcoin Core has built-in commands to retrieve data, generate addresses, send transactions, and more. The RPC console is a great way to get started if you are interested in developing bitcoin applications or just learning more about operating a bitcoin node. We will be exploring some basic commands to retrieve information about the network, blockchain, and transactions.

Once you have installed bitcoin and waited to sync your node to the network, open up the console. It can be found in the window dropdown when running bitcoin-qt (GUI for Bitcoin Core).

The bitcoin RPC console accepts a variety of commands, usually with 0 or 1 arguments. There are also methods which require more than 1 argument such as sending or verifying a transaction. A full list of RPC commands can be found here. In this tutorial we will be using the following basic commands to get familiar with the console:

General Info

getblockchaininfo
getmininginfo
getpeerinfo

Block Info

getblockcount
getbestblockhash
getblock hash
getblockhash index

Transaction Info

getrawmempool
getrawtransaction txid
decoderawtransaction rawtx

General Info Commands

These commands will each return an object with with a variety of information. For example,

> getblockchaininfo

returns:

{
  "chain": "main",
  "blocks": 582101,
  "headers": 582101,
  "bestblockhash": "000000000000000000165bf4a8eaa460df4752002840009c29ec0adfd9376406",
  "difficulty": 7409399249090.253,
  "mediantime": 1561321207,
  "verificationprogress": 0.9999922936147396,
  "initialblockdownload": false,
  "chainwork": "000000000000000000000000000000000000000006d23718c9e22adc4275b706",
  "size_on_disk": 257091100656,
  "pruned": false,
  "softforks": [
    {
      "id": "bip34",
      "version": 2,
      "reject": {
        "status": true
      }
    },
    {
      "id": "bip66",
      "version": 3,
      "reject": {
        "status": true
      }
    },
    {
      "id": "bip65",
      "version": 4,
      "reject": {
        "status": true
      }
    }
  ],
  "bip9_softforks": {
    "csv": {
      "status": "active",
      "startTime": 1462060800,
      "timeout": 1493596800,
      "since": 419328
    },
    "segwit": {
      "status": "active",
      "startTime": 1479168000,
      "timeout": 1510704000,
      "since": 481824
    }
  },
  "warnings": ""
}

There is a great deal of information in this one command. It gives us all the details we need to identify the best block and where to find it. We can also see the size of the blockchain and various soft forks implemented.

A second general info command,

> getmininginfo

returns the following object:

{
  "blocks": 582102,
  "difficulty": 7409399249090.253,
  "networkhashps": 6.626238141514776e+019,
  "pooledtx": 3527,
  "chain": "main",
  "warnings": ""
}

The blocks and difficulty values are also in the getblockchaininfocommand, but here we can find:

network hashes per second
number of transactions in the tx pool

The third general info command is to find out information about the peers your node is communicating blockchain data with. This command:

> getpeerinfo

returns an array of objects. Each object has information about a peer’s node to which your Bitcoin Core instance is currently connected. This number generally ranges from 10–50 if you have port 8333 open on your router (more info on opening ports here). The information returned includes:

IP address information
time since last sent/received
node connected time (uptime)
version/subversion
additional network info

the total number of peers in this array indicates the connection count, however you can also use the command getconnectioncount to return a numerical value of connected nodes.

Block Commands

To retrieve data about a block, we first need a block index or hash to identify that block. We can retrieve both values about the current best block on the chain by using the commands:

> getblockcount

to return the current best block index:

> getbestblockhash

to return the current best block hash:

000000000000000000227508581434096917b80e3a4c981116cc8ff532aa48ef

Each block on the bitcoin blockchain has an index and a hash we can use to find details about it. Blocks can be looked up directly with the a block hash, or indirectly with a block index. For example, say we know that we want to look up the block with height (index) 530120. First type the command:

> getblockhash 530120

which returns the hash:

00000000000000000025c3a8404acf1cabc9fe0a2901f59828128c3bb16f7616

next use the getblock command to retrieve the block data:

> getblock 00000000000000000025c3a8404acf1cabc9fe0a2901f59828128c3bb16f7616

The getblock command called with a specific hash will return:

number of confirmed blocks since that block
block size
block weight
merkle root
an array of all the tx ids in the block
time when the block was mined
the block nonce
the currently difficulty
number of transactions (nTx)
the next/previous block hashes

Transaction Commands

Bitcoin doesn’t index transactions by default. To look up transactions other than those associated with your wallet, you must first turn on indexing in the config file. Go to Settings >> Options >> Open Configuration File to open up the bitcoin configuration file (bitcoin.conf).

Add the line:

txindex=1

With this command added, save the file and restart Bitcoin Core. This process can take several hours, so it is useful to setup overnight, or while you are away. Once Bitcoin Core has indexed the blockchain, any transaction can be looked up individually using the getrawtransaction and decoderawtransactioncommands.

This may seem like a tedious extra step, but keep in mind this setting is also a requirement to running a lightning node.

Now that we have an indexed bitcoin node running, lets find some transactions to decode. We can see the ids of all the transactions in the mempool with the command

> getrawmempool

this command will return an array of (usually) thousands of pending transactions currently in the mempool.

We can look up a specific transaction by selecting one of these transaction ids.

> getrawtransaction 68ecbf8b6d78db0aa4969feb65c6d600bde02f33dbc84151139964fcf448af55

this will return the raw transaction:

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

This hexadecimal string, let’s call it hex, is the encoded transaction and can be decoded using:

> decoderawtransaction hex

This command returns an object with details about that transaction


{
  "txid": "68ecbf8b6d78db0aa4969feb65c6d600bde02f33dbc84151139964fcf448af55",
  "hash": "68ecbf8b6d78db0aa4969feb65c6d600bde02f33dbc84151139964fcf448af55",
  "version": 1,
  "size": 284,
  "vsize": 284,
  "weight": 1136,
  "locktime": 0,
  "vin": [
    {
      "txid": "ea25433a0594c8e7d682854810dbfc3cc676cedde4f094b27a29aef8af73fb52",
      "vout": 0,
      "scriptSig": {
        "asm": "3045022100bc7852636a24fd1da1e14d04abc2c8a467b45f5f7922be47ed8cbd5f571904af0220239cb094a40a4b5d812096b82354bc4470823aeaf8658dd9c71a43327f4a29cd[ALL] 02a1703f0092c3de5106379bce7fbf8689263e31ea8ed41723c8533c28de62cf16",
        "hex": "483045022100bc7852636a24fd1da1e14d04abc2c8a467b45f5f7922be47ed8cbd5f571904af0220239cb094a40a4b5d812096b82354bc4470823aeaf8658dd9c71a43327f4a29cd012102a1703f0092c3de5106379bce7fbf8689263e31ea8ed41723c8533c28de62cf16"
      },
      "sequence": 4294967295
    }
  ],
  "vout": [
    {
      "value": 0.00556057,
      "n": 0,
      "scriptPubKey": {
        "asm": "OP_DUP OP_HASH160 bf1cccd8e4256b5258ce66849e05f4a59f1edb8d OP_EQUALVERIFY OP_CHECKSIG",
        "hex": "76a914bf1cccd8e4256b5258ce66849e05f4a59f1edb8d88ac",
        "reqSigs": 1,
        "type": "pubkeyhash",
        "addresses": [
          "1JRWZiGXAm9n3b5FXopkW1wPifAtXwfjWC"
        ]
      }
    },
    {
      "value": 0.00000000,
      "n": 1,
      "scriptPubKey": {
        "asm": "OP_RETURN 0003ad250002c5239e661ae029df7a66f02955e7a322413e8fbeb6448072b87b7a7c1304ac111052848276bb2bbbf5ad6612436a5d0fe8370702bd541feb2ffa416fa6194a21eb30a2be3060387bf871",
        "hex": "6a4c500003ad250002c5239e661ae029df7a66f02955e7a322413e8fbeb6448072b87b7a7c1304ac111052848276bb2bbbf5ad6612436a5d0fe8370702bd541feb2ffa416fa6194a21eb30a2be3060387bf871",
        "type": "nulldata"
      }
    }
  ]
}

Here we have the

transaction size
transaction weight
input details
output details and value/s

There is plenty of information here, but notice that transaction above doesn’t have any values associated with its input. The block which the transaction was confirmed in isn’t available either in the transaction. These details are missing on purpose to keep the blockchain from repeating unnecessary data. We do have enough information however to look up the amounts received in every bitcoin transaction, and the ability to look up previous transaction outputs. Using these commands is enough to build a basic block explorer.

Summary

The Bitcoin Core RPC console is at the center of using a bitcoin node to facilitate transactions and build applications. Each bitcoin instance has access to a near immutable shared database of previous transaction history as well as network and mining information.

Understanding some of these basic commands is a critical step in bitcoin application development and node operations in general. These commands can be accessed by a multitude of different programming languages to build APIs and applications which use and implement transaction logic. It is possible to run a business from your own node, and track each transaction programmatically through an application with a custom user interface.