Update README

README.md

@@ -49,6 +49,18 @@ $ ./mythril.py -a code.easm
 
 The virtual machine language is described in the [Ethereum Yellowpaper](http://gavwood.com/paper.pdf).
 
+### Tracing EVM execution
+
+You can run a piece of bytecode in the [PyEthereum](https://github.com/ethereum/pyethereum) VM and trace its execution using the `-t` flag. This will output the instructions executed as well as the state of the stack for every execution step. 
+
+```bash
+$ ./mythril.py -t -c "0x606060405050" 
+vm address=b'\x01#Eg\x89\xab\xcd\xef\x01#Eg\x89\xab\xcd\xef\x01#Eg' gas=b'1000000' storage={'storage': {}, 'balance': '0', 'nonce': '0', 'code': '0x'} steps=0 depth=0 pushvalue=96 stack=[] pc=b'0' op=PUSH1 inst=96
+vm gas=b'999997' steps=1 depth=0 pushvalue=64 stack=[b'96'] pc=b'2' op=PUSH1 inst=96
+vm gas=b'999994' steps=2 depth=0 stack=[b'96', b'64'] pc=b'4' op=POP inst=80
+vm gas=b'999992' steps=3 depth=0 stack=[b'96'] pc=b'5' op=POP inst=80
+```
+
 ### Disassembling a contract from the Ethereum blockchain
 
 You can also load code from an existing contract in the Ethereum blockchain. For this, you need to have a full node running, and the RPC debug interface must be activated. For example, when running `geth` you can do this as follows:
@@ -60,7 +72,7 @@ $ geth --syncmode full --rpc --rpcapi eth,debug
 To load contract code from your node, pass the TxID of the transaction that created the contract:
 
 ```bash
-$ ./mythril.py -d -t 0x23112645da9ae684270de843faaeb44918c79a09e019d3a6cf8b87041020340e -o some_contract.easm
+$ ./mythril.py -d --txid 0x23112645da9ae684270de843faaeb44918c79a09e019d3a6cf8b87041020340e -o some_contract.easm
 ```
 
 Note: If you want to get code from the Ethereum mainnet, it is easier to download it from [Etherscan](https://etherscan.io).

mythril.py

@@ -18,12 +18,12 @@ def exitWithError(message):
 
 parser = argparse.ArgumentParser(description='Ethereum VM bytecode assembler/ disassembler')
 
-parser.add_argument('-d', '--disassemble',  action='store_true', help='disassemble, use with -c or  --transaction_hash')
+parser.add_argument('-d', '--disassemble',  action='store_true', help='disassemble, use with -c or  --txid')
 parser.add_argument('-a', '--assemble', help='produce bytecode from easm input file', metavar='INPUT FILE')
 parser.add_argument('-t', '--trace',  action='store_true', help='trace bytecode provided via the -c argument')
 parser.add_argument('-c', '--code', help='bytecode string ("6060604052...")', metavar='BYTECODE')
 parser.add_argument('-o', '--outfile')
-parser.add_argument('--transaction_hash', help='id of contract creation transaction')
+parser.add_argument('--txid', help='id of contract creation transaction')
 parser.add_argument('--rpchost', default='127.0.0.1', help='RPC host')
 parser.add_argument('--rpcport', type=int, default=8545, help='RPC port')
 
@@ -34,17 +34,17 @@ if (args.disassemble):
 
     if (args.code):
         encoded_bytecode = args.code
-    elif (args.transaction_hash):
+    elif (args.txid):
 
         try:
 
-            encoded_bytecode = util.bytecode_from_blockchain(args.transaction_hash, args.rpchost, args.rpcport)
+            encoded_bytecode = util.bytecode_from_blockchain(args.txid, args.rpchost, args.rpcport)
 
         except Exception as e:
             exitWithError("Exception loading bytecode via RPC" + str(e.message))
 
     else:
-        exitWithError("Disassembler: Provide the input bytecode via the -c or --transaction_hash arguments")
+        exitWithError("Disassembler: Provide the input bytecode via the -c or --txid arguments")
 
     disassembly = asm.disassemble(util.safe_decode(encoded_bytecode))