:bd - deletes the current buffer, error if there are unwritten changes
:bd! - deletes the current buffer, no error if unwritten changes
:bufdo bd - deletes all buffers, stops at first error (unwritten changes)
:bufdo! bd - deletes all buffers except those with unwritten changes
:bufdo! bd! - deletes all buffers, no error on any unwritten changes
:bw - completely deletes the current buffer, error if there are unwritten changes
:bw! - completely deletes the current buffer, no error if unwritten changes
:bufdo bw - completely deletes all buffers, stops at first error (unwritten changes)
:bufdo! bw - completely deletes all buffers except those with unwritten changes
:bufdo! bw! - completely deletes all buffers, no error on any unwritten changes
:set confirm - confirm changes (Yes, No, Cancel) instead of error