On 03/17/2014 10:41 AM, Pádraig Brady wrote: > On 03/17/2014 05:06 AM, Александр Ботов wrote: >> Good day! >> >> I've tried to use option -uD to discard the first repeated line as it >> written in info, but it discards the last one. >> >> In the info said that for this purpose I should use option -u not by itself, >> but doesn't said what dose it mean. Could you said (and may be add to the >> man/info) how to use option -u to discard _the first_ repeated line, please? >> >> I use Scientific Linux SL release 5.4 (Boron), Linux version >> 2.6.18-92.1.10.el5.mk8 (gcc version 4.1.2 20070626 (Red Hat 4.1.2-14)), uniq >> (GNU coreutils) vesion 5.97. >> >> Best regards, Alexander. > > So the description in question is: > > `-u' > `--unique' > Discard the first repeated line. When used by itself, this option > causes `uniq' to print unique lines, and nothing else. > > Showing all combinations of options with the particular > one in question at the end shows that we always discard > later lines in a group. > > $ cat in 1 a 2 a 3 a 1 b 2 b 1 c > > $ for o in '' '-d' '-D' '-u' '-ud' '-dD' '-uD'; do echo "$=== $o ===="; > src/uniq $o -f1 in; done > 1 a > 2 a > 3 a > 1 b > 2 b > 1 c > $=== ==== > 1 a > 1 b > 1 c > $=== -d ==== > 1 a > 1 b > $=== -D ==== > 1 a > 2 a > 3 a > 1 b > 2 b > $=== -u ==== > 1 c > $=== -ud ==== > $=== -dD ==== > 1 a > 2 a > 3 a > 1 b > 2 b > $=== -uD ==== > 1 a > 2 a > 1 b > > > Now discarding a single item from a repeated group is unusual, > whether one is discarding the first or the last. > We should at least clarify the documentation, but please > consider adjusting the sort(1) to select between these. > I.E. for the above example: sort -r in -k2,2 Pushing the attached. thanks, Pádraig.
uniq-uD-clarification.patch
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