What happens if I use bitcoin-cli's abandontransaction command (https://chainquery.com/bitcoin-api/abandontransaction) on an unconfirmed transaction that is still on the mempool? Is there any risk of doing this? Will all my spent amounts return back to my original input?

Hello,

I have made 2 payments via bitcoin-cli about 24 hours ago. One had a 120 sat per byte fee, the other one had a 160 sat per byte fee. The problem is that these transactions are not yet confirmed on the blockchain (probably because the 200k+ unconfirmed transactions).
Now, I have 2 addresses with funds (0.1 and 0.2 both with 0 confirmations). bitcoin-cli shows a balance of 0.3 even if both the addresses has 0 confirmations.
Now, what happens if I try to spend these amounts? Can I spend them?
Also, if I set a higher fee (for example 6-800 sat per byte) for a new transaction, will this mean my earlier 2 transactions will also be confirmed faster?

Thanks in advance for your comments!

Is there any tutorial on how to use bitcoin-cli to send an RBF transaction?
Can someone give me some hints on how to do this. Thank you.

If I have an encrypted wallet.dat file under bitcoin core, and I frequently use the getnewaddress and addwitnessaddress commands, how often should I backup the wallet.dat file?

Thank you!

I made a transaction where I used bitcoin core's segwit addresses. There were 2 inputs, both segwit addresses (with a total balance of 2.5).
I used sendmany and sent to 3 outputs (1 segwit and 2 legacy addresses) a total of about 1.95. The strange thing is that the change of about 0.55 came back to a non segwit address to my wallet (address starting with 1).

My question is: is this normal? I assume that if I send from a segwit address, the change should also come back to a segwit address. Wrong?

The 2nd question is about fees. Before transaction, I set a fee of 0.0045. bitcoin-cli settxfee 0.0045
Yet, when I check the transaction on blockchain.info it states that I only have: Fee per byte 301.537 sat/B.
So, basically I set 450 sat/B but when I sent out, the fee used was only 301 sat/B. Why is that?

Does this have anything to do with the weight?

I see this:
Size    488 (bytes)
Weight    1304

Why did it set a lower sat/B fee than what I set?

Your comments are appreciated.

I have a bitcoin core setup under a specific linux user name: xbt.
I would like to run bitcoin-cli with the root user. For this, I wrote a shell script, xbt-bitcoin.sh:

#!/bin/bash

/home/xbt/bitcoin-0.15.0/bin/bitcoin-cli -conf=/home/xbt/.bitcoin/bitcoin.conf $@

So basically this shell script pass all arguments to my bitcoin-cli and it is working very well for simple commands like:
./xbt-bitcoin.sh getbalance
./sbt-bitcoin.sh getnewaddress
./xbt-bitcoin.sh getbalance "AccountName"
etc.

However, I have issues with more complex commands like:

.xbt-bitcoin.sh sendmany "" "{\"address1\":0.02,\"address2\":0.01}" 1 ""
I get an error like:

"error code: -1
error message:
JSON value is not an object as expected"

I guess something is wrong with the way I pass the arguments via the shell script but I can't figure it out how to resolve this.
What can be wrong here?

As far as I know, the size of a transaction is based on number of inputs (input * 146) and number of outputs (output * 34) + about 10 bytes. It is not based on the transactioned amount, right?
How come that 2 transactions with the same number of inputs and outputs have different size?

For example check this one:
https://blockexplorer.com/tx/17ee6117041ee734e7d7d80cdadc475bf1f623984bd0346fc2192f2f062fd5c3
Blockexplorer states 371 bytes for this transaction which seems to be correct based on the above calculation: 146 * 2 + 34 * 2 + 10 = 370.

And now check this one:
https://blockexplorer.com/tx/f83eac6755eb530ae7640684e887f8083da331c0c465cc16d3f10a179eb21594
Here, blockexplorer states 663 bytes as the transaction size which is nearly double than the 370 bytes.

What is wrong with my assumption?

If walletlock is implemented on bitcoin core, bitcoin-cli send out commands are only working if wallet is unlocked for a certain period of time. What happens in this case with the wallet.dat file?

1. I assume, if somebody is maliciously accessing my wallet.dat file while the wallet is locked, he can import the wallet.dat to another bitcoin core but he can not spend anything without the walletpassphrase, right?
2. What happens if the wallet.dat file is maliciously accessed while the wallet is unlocked? For example, wallet is unlocked for 10 minutes between 5 and 5:10 PM. Somebody is downloading the wallet at 5:01 PM and imports it into another bitcoin core until 5:05 PM. Can he spend all the coins until 5:10 PM without having to unlock the wallet with the walletpassphrase? What about a later time?

On the newest version of bitcoin core there is a declared support for multi wallets.
Can someone explain how does this work on a linux command line interface? I couldn't find anything explained on documentation.

Let's suppose I have 1 BTC in bitcoin core address 'A'. I keep it until block number 491407 (bitcoin gold fork).
After this passed (let's say after 6 blocks in about 1 hour), I transfer out the 1 BTC to another address I own 'B'. After this is done, I will get the private key of 'A' address and store it so if needed, I can claim the 1 BTG using this private key.

First question:
- since replay protection is not implemented (at least no information about this), are there any risks of sending out the 1 BTC to another address 1 hour after the fork? Is there any risk of loosing the 1 BTC?
Second question:
- when and if I will import the 'A' address private key to a BTG wallet are there any risks? Is there a possibility that I will not get the 1 BTG? Or is it affecting somehow the already sent out 1 BTC to my 'B' address?

Thanks for the clarifications in advance.

According to this page (https://en.bitcoin.it/wiki/Help:Accounts_explained#The_Default_Account) there is a move function between accounts on our wallet.
Are these moves instant and do not show up on blockchain?

Please check my last test transactions:
{
    "account": "Account2",
    "address": "1AiXzU8AA7NL6oVKrPR9d9hwATKWwMaadS",
    "category": "receive",
    "amount": 0.00100000,
    "label": "Account2",
    "vout": 0,
    "confirmations": 196,
    "blockhash": "0000000000000000007b634b3278a4d75744e77129bb961126246a6e5b7d06a6",
    "blockindex": 1147,
    "blocktime": 1507270616,
    "txid": "2e2d2869cea148a59a1033531042b7590867baba37b2b72b4787bbfcf370b778",
    "walletconflicts": [
    ],
    "time": 1507270440,
    "timereceived": 1507270440,
    "bip125-replaceable": "no"
},   
{
    "account": "Account1",
    "address": "15z2XgtEbjE1dZ4pFuN1FnZvinfYEmGfmg",
    "category": "receive",
    "amount": 0.00100000,
    "label": "Account1",
    "vout": 1,
    "confirmations": 192,
    "blockhash": "00000000000000000095b8f42ab53956052145534d9e1683c3b1a97668b5d802",
    "blockindex": 949,
    "blocktime": 1507274365,
    "txid": "39fc0d67a5c4830e8092654d28b555943f73f4f228c5dd837f6610a7c39243f2",
    "walletconflicts": [
    ],
    "time": 1507270616,
    "timereceived": 1507270616,
    "bip125-replaceable": "no"
},
{
    "account": "Account2",
    "category": "move",
    "time": 1507274482,
    "amount": -0.00100000,
    "otheraccount": "Account1",
    "comment": ""
},
{
    "account": "Account1",
    "category": "move",
    "time": 1507274482,
    "amount": 0.00100000,
    "otheraccount": "Account2",
    "comment": ""
}

So I received 0.001 to both Account1 and Account2 then moved 0.001 from Account1 to Account2.

However, this move does not have a transaction id and if I check on blockchain, the 2 addresses have the same balance (0.001).

https://blockchain.info/address/1AiXzU8AA7NL6oVKrPR9d9hwATKWwMaadS
https://blockchain.info/address/15z2XgtEbjE1dZ4pFuN1FnZvinfYEmGfmg

We would like to offer wallet service for hundreds / thousands of our clients. We want to make it as secure as possible.
Based on what is described here:

"- Make one cross browser compatible web version and add browser side encryption feature than you can use bitaddress.org script to create bitcoin address and encrypted private key (using password entered by your client), than store that encrypted private key in your server.
- Give those encrypted private key some identifier or simply tie it up with users email so your script can identify which encrypted private key it should look at when users try to sign in.
- Now you can show balances from that address in user's dashboard and for added security you can add 2FA.
- If you want to run a profitable bitcoin wallet than set some fix fees (recommended network fee + your profit) after you will get really good number of users using your wallet on daily basis."

We will use the importprivkey bitcoin-cli command to add account to wallet and create "Account1", "Account2", "Account3", etc. accounts. How can we protect these accounts so Account1 will only be able to see and spend what is on Account1?

Or, is there a way that we only import the private key from the account temporarily (by decrypting the above mentioned encrypted private key with user's password) and drop it right after account is logged out?

We would like to offer bitcoin wallets to our clients.
What is the best and most secure way to do this? Preferably we would not want to store the private keys of the address due to security issues but as I understand, there is no way to do this. So probably, the best way would be to secure the wallets as much as possible.
We are familiar with bitcoin-cli, blockchain.info API, PHP, Perl, databases, blockchain, 2FA, and various other APIs.

We want to achieve the following:
- client can access his / her wallet from the web or mobile apps
- client can only see and spend the funds that are on his account
- the most secure way to store the funds (basically noone should be able to access client's funds except the client, not even me as website owner or any of my developers... )

Right now, our own wallet is on a standalone server running under bitcoin core, where all outgoing ports are closed except SSH for certain IPs.

Your comments and suggestions are quite welcome. Thanks.

We would like to create wallets via API for our clients.
We do not want to store the private keys of the wallet, we want this to be done by a reputable third party. For example we would like to create a blockchain.info wallet for email abc@def.com without us storing anything sensitive about this wallet. Basically all we need is to get back from API the wallet address just created for user: abc@def.com. And then, abc@def.com could go to blockchain.info (or any other provider) and use the wallet directly on their website or through their mobile apps.

Can this be done via blockchain.info API? If not via blockchain.info, what other wallet services you recommend to achieve this?

As most of our users are new to crypto currencies, we would like to make them easy to create their first wallet on our website (without having to send them to blockchain.info, create an account there and then come back to us with their public wallet address).

Your comments and suggestions are more than welcome.