[gregwtmtno]

If you don't have a computer that can read and write the filesystem on the image, it gets a little more complicated. In that case, you might be able to make these changes using a hex editor directly on the Raspbian images.

[superuser2]

Vastly simpler to run Linux in Virtualbox and pass the USB controller for the SD card through.

[davidmaitland]

Yeah it's a pain. Although easy on Linux, shouldn't be too hard on a Mac (Fuse drivers are available). Although if I didn't have one of them I would just use another a Pi 2 with Ethernet.

[justinsaccount]

Not a chance.

[gregwtmtno]

I've done it myself on a FreeBSD RPi image. I don't see why it wouldn't work on linux.

[justinsaccount]

What is the "it" that you did?

Changing a string like 'foo=yes' to 'foo=no ' would be easy enough - as long as the filesystem does not checksum data.

Adding multiple lines to multiple files is not going to work very well.

[gregwtmtno]

I've modified configuration files on a FreeBSD filesystem image with a hex editor to cause it to obtain a dhcp lease and allow password ssh login for the default account. (Linux cannot read/write to the default FreeBSD filesystem.)

This allowed me to set up the RPi headless and keyboardless.

Of course the filesystem was dirty, but it's nothing an fsck couldn't solve.