While it shouldn’t happen when using the official apt-get repositories, if you download software off the Internet and run it then there’s a chance that you’ll see the dreaded bash: ./nameOfProgram: cannot execute binary file: Exec format error. This error, which is usually followed by bash: ./nameOfProgram.sh: Permission denied or something like it, indicates that Ubuntu wasn’t able to interface correctly with the binary you downloaded. This is because while it’s apparently a valid Linux binary, it’s designed for a different chipset than your kernel currently supports.