xargs: Why does order of command line switches matter?

[Buchbinder, Barry (NIH/NIAID) [E]]

On 4/25/2012 6:29 AM, Ronald Fischer wrote:
>Eliot Moss sent the following at Wednesday, April 25, 2012 7:05 AM
>
>> Why do I get a different output in the following two invocations of
>> xargs? I had expected that the relative order of the command line
>> switches (-I, -L) would not matter:
>>
>> $ ls | xargs -I DIR -L 1 echo DIR
>> DIR wontprint.txt
>> DIR x.cmd
>> DIR x.pl
>> DIR x.sh
>> $ ls | xargs -L 1 -I DIR echo DIR
>> wontprint.txt
>> x.cmd
>> x.pl
>> x.sh
>
>I agree that that is what happens, and that it does seem strange
>and buggy. I note, though, that -I *implies* -L 1, so the -L 1 is
>unnecessary. Perhaps the explicit mention of -L 1 "kills" the -I flag in
>xarg's command line processing. My guess is that this behavior is passed
>on from the upstream implementation and is not specific to cygwin, which
>means that the appeal for a change would probably need to be lodged
>elsewhere ...

From man xargs:

BUGS
       The  -L option is incompatible with the -I option, but perhaps should
       not be.

- Barry
  Disclaimer: Statements made herein are not made on behalf of NIAID.


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