The English Tabor Pipe has only three holes.  One is on the back for the thumb and two are on the front of the instrument.  These pipes were designed to be played with one hand.  Typically, the performer plays a tabor drum with the other hand.  

The pipe has a range of over an octave of a fifth.  Blowing harder allows the player to reach different overtones, and therefore many notes can be played with one fingering.  See the following fingering system 

Despite their size, tabor pipes are loud!  They are designed to be played outdoors.  

Check out this recording of La Volta, a 16th century dance:

There are many varieties of pipes in many cultures.  For musicians who can only use one hand, these pipes need no adaptations.