Assemble shellcode

assemble.sh

#!/bin/bash

if [[ $# -lt 1 ]]; then
	echo "Please pass a file to assemble!"
	exit
fi

tmpfile=$(mktemp --suffix ".o")

yasm -f elf64 $1 -o $tmpfile
shellcode=$(objdump -d $tmpfile | grep '^ ' | cut -d$'\t' -f2 | sed -r 's/([a-z0-9]{2})/\\x\1/g' | tr -d '[:space:]')

echo $shellcode

if [[ $shellcode == *"\x00"* ]]; then
	printf "\n\t:( \t Your shellcode contains a null byte!\n\n"
	objdump -d $tmpfile | tail -n +8 | cut -d$'\t' -f2- | grep --color ' 00\|$'
else
	printf "\n\t:) \t Your shellcode does not contain any null bytes!\n"
fi