Geth Command Summary

Geth from the command line

Action	Command
Run geth	`geth --datadir ./data/ --networkid 12345678 --maxpeers 1`
Run geth with http server flags	`geth --datadir ./data/ --networkid 12345678 --maxpeers 1 --http --http.corsdomain="package://6fd22d6fe5549ad4c4d8fd3ca0b7816b.mod" --http.api web3,eth,debug,personal,net --vmdebug --allow-insecure-unlock`
Attach to node (opens prompt)	`geth attach path/to/geth.ipc`
Attach to node with preload script	`geth --preload preload.js attach path/to/geth.ipc`

Commands in geth

Action	Command
Get account balance (wei)	`eth.getBalance(eth.coinbase)`
Get account balance (eth)	`web3.fromWei(eth.getBalance(eth.coinbase), "ether")`
Current block number	`eth.blockNumber`
Unlock account	`personal.unlockAccount(eth.coinbase);`
Unlock account until geth exits	`personal.unlockAccount(eth.coinbase, "password", 0)`
Send money	`eth.sendTransaction({from:eth.coinbase, to:'0xaddress', value:web3.toWei(1,"ether"), gas:21000});`
Get info on transaction	`eth.getTransactionReceipt("0xtransactionhash")`
Pending transactions	`eth.pendingTransactions`

Calling a contract

Action	Command
Set contract address	`var addr = '0xaddress';`
Set ABI	`var abi = [...];`
Create interface	`var interface = eth.contract(abi);`
Get contract	`var contract = interface.at(addr);`
Show variable’s value	`contract.num_entries.call()`
Get value from mapping	`contract.entries.call(0)`
Get field from struct from mapping	`contract.entries.call(0)[2]`
Call `view` or `pure` method with no parameters	`contract.methodName.call()`
Call `view` or `pure` method with one parameter	`contract.methodName.call(2)`
Unlock account	`personal.unlockAccount(eth.coinbase,"password",0)`
Call method via transaction (requires mining)	`contract.methodName.sendTransaction("param1","param2", {from:eth.coinbase, gas:1000000})`

Preloading a script

Create a preload.js script such as the one below, and then start geth’s attach with the --preload preload.js parameter, as described above.

What the functions do:

checkAllBalances() will print out all the balances, in ETH, for all of the accounts in eth.accounts
getRevertReason() will, when passed a transaction hash that reverted, attempt to determine why it reverted

function checkAllBalances() { 
    // this function from https://stackoverflow.com/questions/32312884/how-do-i-get-the-balance-of-an-account-in-ethereum
    var i =0;
    var total = 0;
    for ( var i = 0; i < eth.accounts.length; i++ ) {
        var e = eth.accounts[i];
        console.log("  eth.accounts["+i+"]: " +  e + " \tbalance: " + web3.fromWei(eth.getBalance(e), "ether") + " ether");
         total += parseFloat(web3.fromWei(eth.getBalance(e), "ether"));
    }
    console.log("Total: " + total + " ETH");
}

function getRevertReason(txhash) {
    tx=eth.getTransaction(txhash);
    tx.data=tx.input;
    eth.call(tx,tx.blockNumber-1);
}