-bash: ./aapt: No such file or directory

I don't know why https://code.google.com/p/android-apktool/ does not release the x64 version of aapt

# file aapt
aapt: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.8, not stripped

But when you run aapt and seeing that "No such file", you can simply enable the i386 architecture and install the i386 libs to fix it

Here is how you fix it in Debian / Ubuntu:

dpkg --add-architecture i386
apt-get update
apt-get install libncurses5:i386 libstdc++6:i386 zlib1g:i386