The -n and -u sort options combine in a way I hadn't expected.
Given the input:
1234,1,2,3
1234,5,2,3
sort -n -u returns only:
1234,1,2,3
When I had expected it to return both lines.
The man page says:
-u For the default case or the -m option, only output the
first of a sequence of lines that compare equal. For the
-c option, check that no pair of consecutive lines compares
equal.
leading me to believe that while it would sort on a numeric
key, the utility would still do the uniqueness test on the
entire line.
