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04_2__Interlude_Using_JQ.md
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@ -13,7 +13,7 @@ Once you've downloaded the binary, you can install it on your system. If you're
$ mv jq-linux64 jq $ mv jq-linux64 jq
$ sudo /usr/bin/install -m 0755 -o root -g root -t /usr/local/bin jq $ sudo /usr/bin/install -m 0755 -o root -g root -t /usr/local/bin jq
``` ```
_What is JQ?_ The repository explains it best, saying "jq is like sed for JSON data - you can use it to slice and filter and map and transform structured data with the same ease that sed, awk, grep and friends let you play with text." > :book: ***What is JQ?*** The repository explains it best, saying "jq is like sed for JSON data - you can use it to slice and filter and map and transform structured data with the same ease that sed, awk, grep and friends let you play with text."
## Use JQ to Access a JSON Object Value by Key ## Use JQ to Access a JSON Object Value by Key
@ -23,7 +23,7 @@ In the previous section, the use of `signrawtransaction` offered an example of n
``` ```
$ bitcoin-cli signrawtransactionwithwallet $rawtxhex $ bitcoin-cli signrawtransactionwithwallet $rawtxhex
{ {
"hex": "0200000001735dfa1584b930a78ad2c1d6db72dd2a80ae5e5d552ad97e19f1d50d41fdd6d8000000006a47304402202210ce4b2a037da02622c380278cd79fec4e0e016e66f3eb894a2dcbb9ee998f02202cac167e6abdbbf08af139fb7c6b86e9d2e58e5516cd566ae2d54953ead9923b012102111bb978a3c93a00038ae344a1a017d7fee8a9be9d0558b5793ce6f440704a96ffffffff01b0e78604000000001976a914e7c1345fc8f87c68170b3aa798a956c2fe6a9eff88ac00000000", "hex": "02000000013a6e4279b799791049e1826602e84d2e36797e2005887b98c3ecf16b01b7f361010000006a4730440220335d15a2a2ca3ce6a302ce041686739d4a38eb0599a5ea08305de71965268d05022015f77a33cf7d613015b2aba5beb03088033625505ad5d4d0624defdbea22262b01210278608b54b8fb0d8379d3823d31f03a7c6ab0adffb07dd3811819fdfc34f8c132ffffffff01409c0000000000001976a914e7c1345fc8f87c68170b3aa798a956c2fe6a9eff88ac00000000",
"complete": true "complete": true
} }
``` ```
@ -34,17 +34,17 @@ To use JQ, run `jq` at the backend of a pipe, and always use the standard invoca
To capture a specific value from a JSON object, you just list the key after the `.`: To capture a specific value from a JSON object, you just list the key after the `.`:
``` ```
$ bitcoin-cli signrawtransactionwithwallet $rawtxhex | jq -r '.hex' $ bitcoin-cli signrawtransactionwithwallet $rawtxhex | jq -r '.hex'
0200000001735dfa1584b930a78ad2c1d6db72dd2a80ae5e5d552ad97e19f1d50d41fdd6d8000000006a47304402202210ce4b2a037da02622c380278cd79fec4e0e016e66f3eb894a2dcbb9ee998f02202cac167e6abdbbf08af139fb7c6b86e9d2e58e5516cd566ae2d54953ead9923b012102111bb978a3c93a00038ae344a1a017d7fee8a9be9d0558b5793ce6f440704a96ffffffff01b0e78604000000001976a914e7c1345fc8f87c68170b3aa798a956c2fe6a9eff88ac00000000 02000000013a6e4279b799791049e1826602e84d2e36797e2005887b98c3ecf16b01b7f361010000006a4730440220335d15a2a2ca3ce6a302ce041686739d4a38eb0599a5ea08305de71965268d05022015f77a33cf7d613015b2aba5beb03088033625505ad5d4d0624defdbea22262b01210278608b54b8fb0d8379d3823d31f03a7c6ab0adffb07dd3811819fdfc34f8c132ffffffff01409c0000000000001976a914e7c1345fc8f87c68170b3aa798a956c2fe6a9eff88ac00000000
``` ```
With that tool in hand, you can capture information from JSON objects to command-line variables: With that tool in hand, you can capture information from JSON objects to command-line variables:
``` ```
$ signedtx=$(bitcoin-cli signrawtransactionwithwallet $rawtxhex | jq -r '.hex') $ signedtx=$(bitcoin-cli signrawtransactionwithwallet $rawtxhex | jq -r '.hex')
$ echo $signedtx $ echo $signedtx
0200000001735dfa1584b930a78ad2c1d6db72dd2a80ae5e5d552ad97e19f1d50d41fdd6d8000000006a47304402202210ce4b2a037da02622c380278cd79fec4e0e016e66f3eb894a2dcbb9ee998f02202cac167e6abdbbf08af139fb7c6b86e9d2e58e5516cd566ae2d54953ead9923b012102111bb978a3c93a00038ae344a1a017d7fee8a9be9d0558b5793ce6f440704a96ffffffff01b0e78604000000001976a914e7c1345fc8f87c68170b3aa798a956c2fe6a9eff88ac00000000 02000000013a6e4279b799791049e1826602e84d2e36797e2005887b98c3ecf16b01b7f361010000006a4730440220335d15a2a2ca3ce6a302ce041686739d4a38eb0599a5ea08305de71965268d05022015f77a33cf7d613015b2aba5beb03088033625505ad5d4d0624defdbea22262b01210278608b54b8fb0d8379d3823d31f03a7c6ab0adffb07dd3811819fdfc34f8c132ffffffff01409c0000000000001976a914e7c1345fc8f87c68170b3aa798a956c2fe6a9eff88ac00000000
``` ```
You can then use those variables easily and without error: You can then use those variables easily and without error:
``` ```
$ bitcoin-cli sendrawtransactionwithwallet $signedtx $ bitcoin-cli sendrawtransaction $signedtx
3f9ccb6e16663e66dc119de1866610cc4f7a83079bfec2abf0598ed3adf10a78 3f9ccb6e16663e66dc119de1866610cc4f7a83079bfec2abf0598ed3adf10a78
``` ```
## Use JQ to Access Single JSON Object Values in an Array by Key ## Use JQ to Access Single JSON Object Values in an Array by Key
@ -53,38 +53,40 @@ $ bitcoin-cli sendrawtransactionwithwallet $signedtx
Grabbing data out of a JSON object is easy, but what if that JSON object is in a JSON array? The `listunspent` command offers a great example, because it'll usually contain a number of different transactions. What if you want to capture specific information from _one_ of them? Grabbing data out of a JSON object is easy, but what if that JSON object is in a JSON array? The `listunspent` command offers a great example, because it'll usually contain a number of different transactions. What if you want to capture specific information from _one_ of them?
When working with a JSON array, the first thing you need to do is tell JQ which index to access. For example, you might have looked through your transactions in `listunspent` and decided that you wanted to work with the first of them. You use `'.[0]'` to access that first element. The `[]` says that we're referencing a JSON array and the `0` says we want the 0th index. When working with a JSON array, the first thing you need to do is tell JQ which index to access. For example, you might have looked through your transactions in `listunspent` and decided that you wanted to work with the second of them. You use `'.[1]'` to access that first element. The `[]` says that we're referencing a JSON array and the `0` says we want the 0th index.
``` ```
$ bitcoin-cli listunspent | jq -r '.[0]' $ bitcoin-cli listunspent | jq -r '.[1]'
{ {
"txid": "2b5f5798359e0e23e02764588166f222d4ce056419dec83c743b72aad171d708", "txid": "91261eafae15ea53dedbea7c1db748c52bbc04a85859ffd0d839bda1421fda4c",
"vout": 1, "vout": 0,
"address": "mjtEqr4Fffd1XtpAkKoDkMBP54mMXJeQ3j", "address": "mjehC2KHzXcBDcwTd4LhZ2GzyzrZ3Kd3ff",
"account": "", "label": "",
"scriptPubKey": "76a9142fe70d51e886b9ef73b76c1743c5a2bb2894db8588ac", "scriptPubKey": "76a9142d573900aa357a38afd741fbf24b075d263ea6e088ac",
"amount": 0.76, "amount": 0.00022,
"confirmations": 6578, "confirmations": 9,
"spendable": true, "spendable": true,
"solvable": true "solvable": true,
"desc": "pkh([d6043800/0'/0'/3']0278608b54b8fb0d8379d3823d31f03a7c6ab0adffb07dd3811819fdfc34f8c132)#nhjc3f8y",
"safe": true
} }
``` ```
You can then capture an individual value from that selected array by (1) using a pipe _within_ the JQ arguments; and then (2) requesting the specific value afterward, as in the previous example. The following would capture the `txid` from the 0th JSON object in the JSON array produced by `listunspent`: You can then capture an individual value from that selected array by (1) using a pipe _within_ the JQ arguments; and then (2) requesting the specific value afterward, as in the previous example. The following would capture the `txid` from the 0th JSON object in the JSON array produced by `listunspent`:
``` ```
$ bitcoin-cli listunspent | jq -r '.[0] | .txid' $ bitcoin-cli listunspent | jq -r '.[1] | .txid'
2b5f5798359e0e23e02764588166f222d4ce056419dec83c743b72aad171d708 91261eafae15ea53dedbea7c1db748c52bbc04a85859ffd0d839bda1421fda4c
``` ```
Carefully note how the `' 's` go around the whole JQ expression _including_ the pipe. Carefully note how the `' 's` go around the whole JQ expression _including_ the pipe.
This method can be used to fill in variables for a UTXO that you want to use: This method can be used to fill in variables for a UTXO that you want to use:
``` ```
$ newtxid=$(bitcoin-cli listunspent | jq -r '.[0] | .txid') $ newtxid=$(bitcoin-cli listunspent | jq -r '.[1] | .txid')
$ newvout=$(bitcoin-cli listunspent | jq -r '.[0] | .vout') $ newvout=$(bitcoin-cli listunspent | jq -r '.[1] | .vout')
$ echo $newtxid $ echo $newtxid
2b5f5798359e0e23e02764588166f222d4ce056419dec83c743b72aad171d708 91261eafae15ea53dedbea7c1db748c52bbc04a85859ffd0d839bda1421fda4c
$ echo $newvout $ echo $newvout
1 0
``` ```
Voila! We could now create a new raw transaction using our 0th UTXO as an input, without having to type in any of the UTXO info by hand! Voila! We could now create a new raw transaction using our 1st UTXO as an input, without having to type in any of the UTXO info by hand!
## Use JQ to Access Matching JSON Object Values in an Array by Key ## Use JQ to Access Matching JSON Object Values in an Array by Key
@ -93,9 +95,8 @@ Voila! We could now create a new raw transaction using our 0th UTXO as an input,
Instead of accessing a single, specific value in a specific JSON object, you could instead access all of a specific value across all the JSON objects. This is done with `.[]`, where no index is specified. For example, this would list all unspent funds: Instead of accessing a single, specific value in a specific JSON object, you could instead access all of a specific value across all the JSON objects. This is done with `.[]`, where no index is specified. For example, this would list all unspent funds:
``` ```
$ bitcoin-cli listunspent | jq -r '.[] | .amount' $ bitcoin-cli listunspent | jq -r '.[] | .amount'
0.76 0.0001
3.9 0.00022
1.95
``` ```
## Use JQ for Simple Calculations by Key ## Use JQ for Simple Calculations by Key
@ -105,9 +106,9 @@ $ bitcoin-cli listunspent | jq -r '.[] | .amount'
At this point, you can start using JQ output for simple math. For example, adding up the values of those unspent transactions with a simple `awk` script would give you the equivalent of `getbalance`: At this point, you can start using JQ output for simple math. For example, adding up the values of those unspent transactions with a simple `awk` script would give you the equivalent of `getbalance`:
``` ```
$ bitcoin-cli listunspent | jq -r '.[] | .amount' | awk '{s+=$1} END {print s}' $ bitcoin-cli listunspent | jq -r '.[] | .amount' | awk '{s+=$1} END {print s}'
6.61 0.00032
$ bitcoin-cli getbalance $ bitcoin-cli getbalance
6.61000000 0.00032000
``` ```
## Use JQ to Display Multiple JSON Object Values in an Array by Multiple Keys ## Use JQ to Display Multiple JSON Object Values in an Array by Multiple Keys
@ -119,15 +120,12 @@ JQ can easily capture individual elements from JSON objects and arrays and place
For example, you might want to see a listing of all your UTXOs (`.[]`) and get a listing of all of their most important information (`.txid, .vout, .amount`): For example, you might want to see a listing of all your UTXOs (`.[]`) and get a listing of all of their most important information (`.txid, .vout, .amount`):
``` ```
$ bitcoin-cli listunspent | jq -r '.[] | .txid, .vout, .amount' $ bitcoin-cli listunspent | jq -r '.[] | .txid, .vout, .amount'
2b5f5798359e0e23e02764588166f222d4ce056419dec83c743b72aad171d708 ca4898d8f950df03d6bfaa00578bd0305d041d24788b630d0c4a32debcac9f36
1
0.76
ec0598918f6f5476cb90365651e8a2724ef26f949290bbf196f41ed96092a52f
0 0
3.9 0.0001
3470e5fe08633583d136b9cd49bb1a224c9d9313a0b4584fd3b7438dbdf34dbd 91261eafae15ea53dedbea7c1db748c52bbc04a85859ffd0d839bda1421fda4c
0 0
1.95 0.00022
``` ```
This makes it easy to decide which UTXOs to spend in a raw transaction, but it's not very pretty. This makes it easy to decide which UTXOs to spend in a raw transaction, but it's not very pretty.
@ -137,38 +135,28 @@ The following example shows the exact same parsing of `listunspent`, but with th
``` ```
$ bitcoin-cli listunspent | jq -r '.[] | { txid: .txid, vout: .vout, amount: .amount }' $ bitcoin-cli listunspent | jq -r '.[] | { txid: .txid, vout: .vout, amount: .amount }'
{ {
"txid": "2b5f5798359e0e23e02764588166f222d4ce056419dec83c743b72aad171d708", "txid": "ca4898d8f950df03d6bfaa00578bd0305d041d24788b630d0c4a32debcac9f36",
"vout": 1, "vout": 0,
"amount": 0.76 "amount": 0.0001
} }
{ {
"txid": "ec0598918f6f5476cb90365651e8a2724ef26f949290bbf196f41ed96092a52f", "txid": "91261eafae15ea53dedbea7c1db748c52bbc04a85859ffd0d839bda1421fda4c",
"vout": 0, "vout": 0,
"amount": 3.9 "amount": 0.00022
}
{
"txid": "3470e5fe08633583d136b9cd49bb1a224c9d9313a0b4584fd3b7438dbdf34dbd",
"vout": 0,
"amount": 1.95
} }
``` ```
You could of course rename your new keys as you see fit. There's nothing magic in the original names: You could of course rename your new keys as you see fit. There's nothing magic in the original names:
``` ```
$ bitcoin-cli listunspent | jq -r '.[] | { tx: .txid, output: .vout, bitcoins: .amount }' $ bitcoin-cli listunspent | jq -r '.[] | { tx: .txid, output: .vout, bitcoins: .amount }'
{ {
"tx": "2b5f5798359e0e23e02764588166f222d4ce056419dec83c743b72aad171d708", "tx": "ca4898d8f950df03d6bfaa00578bd0305d041d24788b630d0c4a32debcac9f36",
"output": 1, "output": 0,
"bitcoins": 0.76 "bitcoins": 0.0001
} }
{ {
"tx": "ec0598918f6f5476cb90365651e8a2724ef26f949290bbf196f41ed96092a52f", "tx": "91261eafae15ea53dedbea7c1db748c52bbc04a85859ffd0d839bda1421fda4c",
"output": 0, "output": 0,
"bitcoins": 3.9 "bitcoins": 0.00022
}
{
"tx": "3470e5fe08633583d136b9cd49bb1a224c9d9313a0b4584fd3b7438dbdf34dbd",
"output": 0,
"bitcoins": 1.95
} }
``` ```
## Use JQ to Access JSON Objects by Looked-Up Value ## Use JQ to Access JSON Objects by Looked-Up Value
@ -369,6 +357,11 @@ $ bitcoin-cli decoderawtransaction $rawtxhex | jq -r '.vout [] | .value' | awk
``` ```
To complete the transaction fee calculation, you subtract the .vout .amount (1.045) from the .vin .amount (1.3). To complete the transaction fee calculation, you subtract the .vout .amount (1.045) from the .vin .amount (1.3).
To do this, you'll need to install `bc`:
```
$ sudo apt-get intall bc
```
Putting it all together creates a complete calculator in just five lines of script: Putting it all together creates a complete calculator in just five lines of script:
``` ```
$ usedtxid=($(bitcoin-cli decoderawtransaction $rawtxhex | jq -r '.vin | .[] | .txid')) $ usedtxid=($(bitcoin-cli decoderawtransaction $rawtxhex | jq -r '.vin | .[] | .txid'))