coreutils       8.13-3.2ubuntu2 (quantal)<br><br>using the attached files:<br>$  LC_ALL=C sort rqb.2012-11-07. &gt;/tmp/pC   #ensure inputs are sorted<br>$  LC_ALL=C sort a0&gt;/tmp/qC<br>$  LC_ALL=C comm -2 /tmp/[pq]C&gt;/tmp/-2<br>

$  LC_ALL=C comm -23 /tmp/[pq]C&gt;/tmp/-23<br><br>the 2 comm commands produce identical output!<br>oughtn&#39;t the latter command only show lines unique to FILE1?