How can I see the 0s and 1s / machine code from a executable file / object file?

Question

I already tried this, I opened a a.out file with a text editor but I get only a bunch of characters with some instructions in it like:

üÙ

Answer 1

Try hexdump. Something like:

$ hexdump -X a.out

It will give you just that: an hexadecimal dump of the file.

Having said that, another possibility might include using GDB's disassemble command.