[Ethereum] How to write transaction logs into a text file in geth

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I have made a contract which generates a public event on blockchain that will notify client about a transaction.
To listen to the event I have written following snippet in geth console:

var event = token.CoinTransfer({}, '', function(error, result){
  if (!error)
    console.log("Coin transfer: " + result.args.amount + " tokens were sent. Balances now are as following: \n Sender:\t" + result.args.sender + " \t" + token.coinBalanceOf.call(result.args.sender) + " tokens \n Receiver:\t" + result.args.receiver + " \t" + token.coinBalanceOf.call(result.args.receiver) + " tokens" )
});

Now instead of console.log() I want these transaction to be stored in a text file TransactionHistory.txt. How can we do this? Is there a better way than listening to event, to maintain transaction logs?

Best Answer

Probably is best that you exec the script from a file anyway

 geth --exec 'loadScript("/tmp/test.js")' attach

Then you can direct the output, for example in Linux and Mac:

 geth --exec 'loadScript("/tmp/checkbalances.js")' attach > log.txt

Send Stderr And Stdout To A Log File

If you want to overwrite the log file each time you start your command:

parity [options] > /tmp/parity.log 2>&1

If you want to append to your log file each time you start your command:

parity [options] >> /tmp/parity.log 2>&1

Send Stderr And Stdout To Separate Log Files While Viewing Output

And if you want to log stderr and stdout into separate log files while viewing the output on your console:

parity [options] > >(tee stdout.log) 2> >(tee stderr.log >&2)

Reference How do I write stderr to a file while using “tee” with a pipe?.

If you want to create a script file to run this command, you will have to use #!/bin/bash (instead of #!/bin/sh) in the first line of the file as this redirection is bash specific:

#!/bin/bash

cd $HOME/Parity

parity [options] > >(tee stdout.log) 2> >(tee stderr.log >&2)

Save the above into $HOME/bin/runParity, chmod 700 $HOME/bin/runParity and your can then type runParity (or $HOME/bin/runParity) to start it.

[Ethereum] How to unsubscribe logs / events

myContractWebsocket.events.MyLogName returns a Subscription response, which has an unsubscribe method. See here for a bit more detail.

Best Answer

Related Solutions

Parity Logs – How to Make Parity Write Logs for Monitoring

Send Stderr And Stdout To A Log File

Send Stderr And Stdout To Separate Log Files While Viewing Output

[Ethereum] How to unsubscribe logs / events

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