Convert Block Number Hash to Readable Block Number?

Question

When i use this command :

curl --data '{"method":"eth_getBlockByNumber","params":["latest", true],"id":1,"jsonrpc":"2.0"}' -H "Content-Type: application/json" -X POST localhost:8544

Then I am getting this response :

{"jsonrpc":"2.0","result":{"author":"0x2a65aca4d5fc5b5c859090a6c34d164135398226","difficulty":"0x23796dec9350","extraData":"0xd783010404844765746887676f312e362e32856c696e7578","gasLimit":"0x47e7c4","gasUsed":"0x1e8d3","hash":"0x8918e1c221fca4bbd2686e2b991eedb55e5e07a56867b6444d6064db7a1f2132","logsBloom":"0x00000010000000020000000000020000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000002000000000000000000000000000040000100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000","miner":"0x2a65aca4d5fc5b5c859090a6c34d164135398226","mixHash":"0xd7f23f011e484617fda230b8a123050e9ddb68db0e2107b6e92c354d8d030d36","nonce":"0x7cb02500056bd498","number":"0x178def","parentHash":"0x309ccfe954d223a41165d5f8e79084b8cd8949602d30d5960d837d9fd2c7ab97","receiptsRoot":"0xbdfe515f906a594396675ea4417f2de701e147f6263525fcd2a8e63e955a8d70","sealFields":["0xa0d7f23f011e484617fda230b8a123050e9ddb68db0e2107b6e92c354d8d030d36","0x887cb02500056bd498"],"sha3Uncles":"0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347","size":"0x398","stateRoot":"0x3eca3ea525993d54b46b18a3f65752ee4d18c54d2c4c8e413864aa5b14867327","timestamp":"0x573d35cd","totalDifficulty":"0x11c4f37beb4be0c5c","transactions":[{"blockHash":"0x8918e1c221fca4bbd2686e2b991eedb55e5e07a56867b6444d6064db7a1f2132","blockNumber":"0x178def","chainId":null,"condition":null,"creates":null,"from":"0xea674fdde714fd979de3edf0f56aa9716b898ec8","gas":"0x15f90","gasPrice":"0x4a817c800","hash":"0xf21a395a97066b135278eb589d6e0472fd9d1e592aaada32ad61dc4e34fa7e29","input":"0x","nonce":"0x191a1","publicKey":"0x5d8af02c52b1fb40e45d6e04ae2351d443d1f7327e9b6dbb5ae1d918414899c625690c4c236889e23d9705f9db88876542b959d947a3497a30d0d922ee30015f","r":"0xc34afbc29e616513a28503097652f7ae62b9dbffb9eecc592dd625a0bf34c940","raw":"0xf870830191a18504a817c80083015f909451c7d68f3a4089e6e6d142dee0569b6770e6e335880de326b2f64b16b0801ba0c34afbc29e616513a28503097652f7ae62b9dbffb9eecc592dd625a0bf34c940a018717fbbeeda52a6adb8f2a059e05b72fcff03433e86aeca453eee06ef70cdc6","s":"0x18717fbbeeda52a6adb8f2a059e05b72fcff03433e86aeca453eee06ef70cdc6","standardV":"0x0","to":"0x51c7d68f3a4089e6e6d142dee0569b6770e6e335","transactionIndex":"0x0","v":"0x1b","value":"0xde326b2f64b16b0"},{"blockHash":"0x8918e1c221fca4bbd2686e2b991eedb55e5e07a56867b6444d6064db7a1f2132","blockNumber":"0x178def","chainId":null,"condition":null,"creates":null,"from":"0x4bc6c54e71ea68d069c895983812d426dc296b77","gas":"0x15f90","gasPrice":"0x4a817c800","hash":"0xcceefc4aaab15712582d5c96e974dd05e5e61bb7c5f5a4bdf5d101ecfa01dc8e","input":"0x","nonce":"0x8","publicKey":"0x4fcb530d5d1140522eee9c3f9263c5bc5aef49b448b7b1aa6cade7706d6d3bb465d732db660caab962f49ce74794bb67dd0510e24c94de0b45832f545733cc4d","r":"0xc321ec233a88e8cbf08c905e4de6fe729f3913fab9f0b36477f609adda5a69bb","raw":"0xf86d088504a817c80083015f909452929b839b37738439337c5b6a107418f6cb8c3588896909229be8a800801ba0c321ec233a88e8cbf08c905e4de6fe729f3913fab9f0b36477f609adda5a69bba02e76bf3d6b8c210968876d6ec7132f7103915d66e9f1ee481126f030227d59d0","s":"0x2e76bf3d6b8c210968876d6ec7132f7103915d66e9f1ee481126f030227d59d0","standardV":"0x0","to":"0x52929b839b37738439337c5b6a107418f6cb8c35","transactionIndex":"0x1","v":"0x1b","value":"0x896909229be8a800"},{"blockHash":"0x8918e1c221fca4bbd2686e2b991eedb55e5e07a56867b6444d6064db7a1f2132","blockNumber":"0x178def","chainId":null,"condition":null,"creates":null,"from":"0xfbb1b73c4f0bda4f67dca266ce6ef42f520fbb98","gas":"0x38eb3","gasPrice":"0x4a817c800","hash":"0x93c27acf3b0bca776975c674eea2be0e4dd103964dc62741de6848f756d95655","input":"0xbaac5300000000000000000000000000f8357a814f15517494d3bac7c93cd405be5a6c06","nonce":"0x4ca3","publicKey":"0x8178af6e1ae9a747de289f2106a85875288b24a2c6bdb1f069cad506409abdd4f1bd1ac05507615c852a9a74cf3013f7b13b9e0f03870011993e575a357a308d","r":"0x55802fbddf75a40105b04ba7915aaf01479c3637b102c38d70682ccda8133f66","raw":"0xf893824ca38504a817c80083038eb394bb9bc244d798123fde783fcc1c72d3bb8c189413888aa20afbc9ce7000a4baac5300000000000000000000000000f8357a814f15517494d3bac7c93cd405be5a6c061ba055802fbddf75a40105b04ba7915aaf01479c3637b102c38d70682ccda8133f66a00c632501b44e702f530f6a4ac6bfc9c3e74b691e5861ad6372c69909eb5ed948","s":"0xc632501b44e702f530f6a4ac6bfc9c3e74b691e5861ad6372c69909eb5ed948","standardV":"0x0","to":"0xbb9bc244d798123fde783fcc1c72d3bb8c189413","transactionIndex":"0x2","v":"0x1b","value":"0x8aa20afbc9ce7000"}],"transactionsRoot":"0x5528494eb8fd3038468c30050e85ef7cca4603c75ad5a3f222630eb92585eb73","uncles":[]},"id":1}

In the above response the block number is : 0x178def . How to convert this block number to readable block number, like example block number 545 ?

Answer 1

On a Linux command line, without using some hideous grep/regex? :-)

Here's a Python2 method (using Infura as the backend):

$ curl -s -X POST --data '{"id":1,"jsonrpc":"2.0", "method":"eth_getBlockByNumber","params":["latest", true]}' -H "Content-Type: application/json" https://mainnet.infura.io/<my_infura_key> | python -c "import sys, json; print(int(json.load(sys.stdin)['result']['number'], 0))"
5065179

So the important part:

<curl_command> | python -c "import sys, json; print(int(json.load(sys.stdin)['result']['number'], 0))"

This pipes the output of your curl command to a Python command, which parses the JSON, reads the correct field, and converts from a hex string into an integer.

I also passed -s to curl to run in silent mode.

You could also pipe the output of the curl command to the jq tool, and do something similar.

Also note that you could just use the eth_blockNumber method, which returns a more simple JSON response.