title: Gnu sort: stray characters in field specification
body: <p><code>sort</code> doesn't seem to like my key specification. Why?</p>
  
  <pre><code>~/tmp $ sort --version
  sort (GNU coreutils) 8.25
  Packaged by Cygwin (8.25-1)
  ~/tmp $ echo 'a;b;c;d;e;f;g'|sort --field-separator=';' --key=1,5,2                                          
  sort: stray character in field spec: invalid field specification '1,5,2'
  </code></pre>
  
  <p>From the man page:</p>
  
  <p><em>-k, --key=KEYDEF : sort via a key; KEYDEF gives location and type</em></p>
  
  <p><em>KEYDEF is F[.C][OPTS][,F[.C][OPTS]] for start and stop position, where F is a field
  number and C a character position in the field; both are origin  1,  and  the  stop
  position defaults to the line's end.</em></p>
  
  <p>Since the .C and OPTS part in the KEYDEF is optional, a key specification F,F,F (i.e. just the field numbers) should be correct. What did I do wrong?</p>
  
  <p>BTW, my environment is Cygwin, running the Z-shell.</p>