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3_4_Receiving_a_Transaction.md
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@ -6,9 +6,11 @@ You're now ready to receive some money at the new address you set up.
## Get Some Money ## Get Some Money
To do anything more, you need to get some money. On testnet this is done through faucets. Since the money is all pretend, you just go to a faucet, request some money, and it's sent over to you. We suggest using the faucet at http://tpfaucet.appspot.com/. If it's not available for some reason, search for "bitcoin testnet faucet", and you should find others. We suggest https://testnet.manu.backend.hamburg/faucet as an excellent alternative. To do anything more, you need to get some money. On testnet this is done through faucets. Since the money is all pretend, you just go to a faucet, request some money, and it will be sent over to you. We suggest using the faucet at https://testnet.manu.backend.hamburg/faucet. If it's not available for some reason, search for "bitcoin testnet faucet", and you should find others. We suggest http://tpfaucet.appspot.com/ as an excellent alternative.
To use a faucet, you'll usually need to go to a URL and copy and paste in your address. Yes, this violates our Best Practices, but that's how the faucets tend to work. To use a faucet, you'll usually need to go to a URL and copy and paste in your address. Note that this is one of those cases where you won't be able to use command-line variables, alas. Afterward, a transaction will be created that sends money from the faucet to you.
_What is a transaction?_ A transaction is a bitcoin exchange. The owner of some bitcoins records that he's sending them to someone else, and signs that record with the appropriate private key.
> **TESTNET vs MAINNET:** Sadly, there are no faucets in real life. If you were playing on the mainnet, you'd need to go and actually buy bitcoins at a bitcoin exchange or ATM, or you'd need to get someone to send them to you. Testnet life is much easier. > **TESTNET vs MAINNET:** Sadly, there are no faucets in real life. If you were playing on the mainnet, you'd need to go and actually buy bitcoins at a bitcoin exchange or ATM, or you'd need to get someone to send them to you. Testnet life is much easier.
@ -21,19 +23,23 @@ $ bitcoin-cli getbalance
``` ```
But wait, there's no balance yet!? But wait, there's no balance yet!?
Welcome to the world of Bitcoin latency. Transactions are transmitted across the network and gathered into blocks by miners. If you don't see a balance, your block hasn't been made yet. However, `bitcoin-cli get unconfirmedbalance` should still show it as long as the initial transaction has been created: Welcome to the world of Bitcoin latency.The problem is that your transaction hasn't yet been recorded in a block!
_What is a block?_ Transactions are transmitted across the network and gathered into blocks by miners. These blocks are secured with a mathematical proof-of-work, which proves that computing power has been expended as part of the block creation. It's that proof-of-work (multiplied over many blocks) that ultimately keeps Bitcoin secure.
Fortunately, `bitcoin-cli get unconfirmedbalance` should still show your updated balance as long as the initial transaction has been created:
``` ```
$ bitcoin-cli getunconfirmedbalance $ bitcoin-cli getunconfirmedbalance
0.47000000 0.47000000
``` ```
If that's still showing a zero too, you're probably moving through this tutorial too fast. Wait a second. The coins should show up unconfirmed, then rapidly move to confirmed. However, if your "getbalance" and your "getunconfirmedbalance" both still show zero in ten minutes, then there's probably something wrong with the faucet, and you'll need to pick another. (Do note that a coin can move from unconfirmedbalance to confirmedbalance almost immediately, so make sure you check both.) If that's still showing a zero too, you're probably moving through this tutorial too fast. Wait a second. The coins should show up unconfirmed, then rapidly move to confirmed. Do note that a coin can move from unconfirmedbalance to confirmedbalance almost immediately, so make sure you check both. However, if your `getbalance` and your `getunconfirmedbalance` both still show zero in ten minutes, then there's probably something wrong with the faucet, and you'll need to pick another.
> **WARNING:** After a block is built and confirmed, another block is built on top of it, and another ... Because this is a stochastic process, there's some chance for reversal when a block is still new. Thus, a block has to be buried several blocks deep in a chain before you can feel total confident in your funds. Each of those blocks tends to be built in an average of 10 minutes ... so it usually takes about an hour for a confirmed transaction to receive full confidence.
### Gain Confidence in Your Money ### Gain Confidence in Your Money
You can use `bitcoin-cli getbalance "\*" [n]` to see if a confirmed balance is 'n' blocks deep. You can use `bitcoin-cli getbalance "\*" [n]` to see if a confirmed balance is 'n' blocks deep.
_What is block depth?_ After a block is built and confirmed, another block is built on top of it, and another ... Because this is a stochastic process, there's some chance for reversal when a block is still new. Thus, a block has to be buried several blocks deep in a chain before you can feel totally confident in your funds. Each of those blocks tends to be built in an average of 10 minutes ... so it usually takes about an hour for a confirmed transaction to receive full confidence.
The following shows that our transaction has been confirmed one time, but not twice: The following shows that our transaction has been confirmed one time, but not twice:
``` ```
$ bitcoin-cli getbalance "*" 1 $ bitcoin-cli getbalance "*" 1
@ -45,9 +51,11 @@ Obviously, every ten minutes or so this depth will increase.
Of course, on the testnet, no one is that worried about how reliable your funds are. You'll be able to spend your money as soon as it's confirmed. Of course, on the testnet, no one is that worried about how reliable your funds are. You'll be able to spend your money as soon as it's confirmed.
_What is a blockchain?_ A blockchain is the linked set of all blocks, starting with the more recently built block and going back to the genesis block. Though Bitcoin created the blockchain technology, there are also other blockchains; some are used for alt-coins and some for other purposes.
## Verify Your Wallet ## Verify Your Wallet
You can also access all of this information with the `bitcoin-cli getwalletinfo` command: The `bitcoin-cli getwalletinfo` command gives you more money on the balance of your wallet:
``` ```
$ bitcoin-cli getwalletinfo $ bitcoin-cli getwalletinfo
{ {
@ -65,7 +73,7 @@ $ bitcoin-cli getwalletinfo
## Discover Your Transaction ID ## Discover Your Transaction ID
Your money came into you via a transaction. You can discover that transactionid (txid) with the `bitcoin-cli listtransactions` command: Your money came into your wallet via a transaction. You can discover that transactionid (txid) with the `bitcoin-cli listtransactions` command:
``` ```
$ bitcoin-cli listtransactions $ bitcoin-cli listtransactions
[ [
@ -91,7 +99,7 @@ $ bitcoin-cli listtransactions
``` ```
This shows one transaction ("88e5d5f3077517d76f5a61491fa52e6aaae078c52bc62d849f09507ef0cfada2") that was received ("receive") by a specific address in my wallet ("n4cqjJE6fqcmeWpftygwPoKMMDva6BpyHf") for a specific amount ("0.47000000"). This shows one transaction ("88e5d5f3077517d76f5a61491fa52e6aaae078c52bc62d849f09507ef0cfada2") that was received ("receive") by a specific address in my wallet ("n4cqjJE6fqcmeWpftygwPoKMMDva6BpyHf") for a specific amount ("0.47000000").
You can access similar information with the `bitcoin-cli listunspent` command, but it only shows the transactions for the money that you haven't spent. These are also called UTXOs, and will be vitally important when you're sending money back out into the Bitcoin world: You can access similar information with the `bitcoin-cli listunspent` command, but it only shows the transactions for the money that you haven't spent. These are called UTXOs, and will be vitally important when you're sending money back out into the Bitcoin world:
``` ```
$ bitcoin-cli listunspent $ bitcoin-cli listunspent
[ [
@ -108,9 +116,9 @@ $ bitcoin-cli listunspent
} }
] ]
``` ```
Note that bitcoins are not just a homogeneous mess of cash jammed into your pocket. Each individual transaction that you receive or that you send is placed in the immutable blockchain ledger, in a block. You can see all of those when you look at your transactions. Note also that this means that bitcoin spending isn't quite as anonymous as you'd think. Though the addresses are fairly private, transactions can be examined as they go in and out of addresses. This makes the funds ultimately fungible and makes the privacy vulnerable to statistical analysis. Note that bitcoins are not just a homogeneous mess of cash jammed into your pocket. Each individual transaction that you receive or that you send is placed into the immutable blockchain ledger, in a block. You can see these individual transactions when you look at your unspent money. Note also that this means that bitcoin spending isn't quite as anonymous as you'd think. Though the addresses are fairly private, transactions can be examined as they go in and out of addresses. This makes the funds ultimately fungible and makes the privacy vulnerable to statistical analysis.
> **TESTNET vs MAINNET:** Why are all of these bitcoin amounts in fractions? Bitcoins are produced slowly, and so there are relatively few in circulation. As a result, each bitcoin over on the mainnet is worth quite a bit (~ $1,200 at the time of this writing). This means that people usually work in fractions. In fact, .47 BTC would be quite a lot in the real-world. You'll often be dealing with even smaller fractions on mainnet. For this reason, names have appeared for smaller amounts of bitcoins, including millibitcoins or mBTCs (one-thousandth of a bitcoin), microbitcoins or bits or μBTCs (one-millionth of a bitcoin), and satoshis (one hundred millionth of a bitcoin). _Why are all of these bitcoin amounts in fractions?_ Bitcoins are produced slowly, and so there are relatively few in circulation. As a result, each bitcoin over on the mainnet is worth quite a bit (~ $1,000 at the time of this writing). This means that people usually work in fractions. In fact, .47 BTC would be quite a lot in the real-world. You'll often be dealing with even smaller fractions on mainnet. For this reason, names have appeared for smaller amounts of bitcoins, including millibitcoins or mBTCs (one-thousandth of a bitcoin), microbitcoins or bits or μBTCs (one-millionth of a bitcoin), and satoshis (one hundred millionth of a bitcoin).
## Examine Your Transaction ## Examine Your Transaction
@ -119,8 +127,6 @@ You can get more information on a transaction with the `bitcoin-cli getrawtransa
$ bitcoin-cli getrawtransaction "88e5d5f3077517d76f5a61491fa52e6aaae078c52bc62d849f09507ef0cfada2" $ bitcoin-cli getrawtransaction "88e5d5f3077517d76f5a61491fa52e6aaae078c52bc62d849f09507ef0cfada2"
010000000133261a25b44689bab2c6a207381ca21d243de9bbf21f0fa40c3a26ba7282a87b000000006b483045022100a2640761810dfc34dabed599928243afe24e13f520f780ceb382843a530a577c022050b92f5d9843d70ddb60a0aa294938862f2b7372818d6149ffd4f6adec5cf6c80121034dcaa515c2fda0f4a50b90a6d798e01c00a870bef0bd97154066fe202d2b5d75feffffff02c029cd02000000001976a914fd67e8a7c7813e7a5c376eb71074f373d924d96888ac17791703000000001976a914e176ee39c642344df2180863e27e2e936307273c88ac07a41000 010000000133261a25b44689bab2c6a207381ca21d243de9bbf21f0fa40c3a26ba7282a87b000000006b483045022100a2640761810dfc34dabed599928243afe24e13f520f780ceb382843a530a577c022050b92f5d9843d70ddb60a0aa294938862f2b7372818d6149ffd4f6adec5cf6c80121034dcaa515c2fda0f4a50b90a6d798e01c00a870bef0bd97154066fe202d2b5d75feffffff02c029cd02000000001976a914fd67e8a7c7813e7a5c376eb71074f373d924d96888ac17791703000000001976a914e176ee39c642344df2180863e27e2e936307273c88ac07a41000
``` ```
> **WARNING:** This command will not work in some situation. To be able to view a raw transaction on a standard node, some of the money must be unspent, or the transaction must still be in your mempool — which means that this command will work fine for the money you've just received, but not for old stuff. If you want to be able to view older transactions that have been entirely spent, you can do so by maintaining a set of all transactions with the txindex=1 configuration, which is what our scripts suggest for all non-pruned instances. (You can't maintain a transaction index if your node is pruned.)
Granted, this isn't super useful, because it's the hex-encoded transaction data. Fortunately, you can get a more verbose description just by adding a '1' to your command: Granted, this isn't super useful, because it's the hex-encoded transaction data. Fortunately, you can get a more verbose description just by adding a '1' to your command:
``` ```
$ bitcoin-cli getrawtransaction "88e5d5f3077517d76f5a61491fa52e6aaae078c52bc62d849f09507ef0cfada2" 1 $ bitcoin-cli getrawtransaction "88e5d5f3077517d76f5a61491fa52e6aaae078c52bc62d849f09507ef0cfada2" 1
@ -177,11 +183,13 @@ $ bitcoin-cli getrawtransaction "88e5d5f3077517d76f5a61491fa52e6aaae078c52bc62d8
"blocktime": 1488307692 "blocktime": 1488307692
} }
``` ```
Now you can see the full information on the transaction, including all of the inputs ("vin") and all the outputs ("vout). One of the interesting things to note is that though we received .47 BTC in the transaction, another .51869975 was sent to another address. That was probably a change address, a concept that is explored more in the next section. It is quite typical for a transaction to have multiple inputs and/or multiple outputs. Now you can see the full information on the transaction, including all of the inputs ("vin") and all the outputs ("vout). One of the interesting things to note is that though we received .47 BTC in the transaction, another .51869975 was sent to another address. That was probably a change address, a concept that is explored in the next section. It is quite typical for a transaction to have multiple inputs and/or multiple outputs.
> **WARNING:** These commands will not work in some situations. To be able to view a raw transaction on a standard node, some of the money must be unspent, or the transaction must still be in your mempool — which means that this command will work fine for the money you've just received, but not for old stuff. If you want to be able to view older transactions that have been spent, you can do so by maintaining a set of all transactions with the txindex=1 configuration, which is what our scripts suggest for all non-pruned instances. (You can't maintain a transaction index if your node is pruned.)
## Optional: Use a Block Explorer ## Optional: Use a Block Explorer
Even looking at the verbose information for a transaction can be a little intimidating. The main goal of this tutorial is to teach about dealing with raw transactions from the command line, but we're happy to talk about other tools when they're applicable. One of those tools is a block explorer, which you can use to look at transactions from a web browser in a much friendlier format. Even looking at the verbose information for a transaction can be a little intimidating. The main goal of this tutorial is to teach how to deal with raw transactions from the command line, but we're happy to talk about other tools when they're applicable. One of those tools is a block explorer, which you can use to look at transactions from a web browser in a much friendlier format.
Currently, our preferred block explorer is [https://live.blockcypher.com/](https://live.blockcypher.com/). Currently, our preferred block explorer is [https://live.blockcypher.com/](https://live.blockcypher.com/).