Shell Programming and Scripting

Sometimes the order matters.
For example, your input file is

Code:

1
2
3
2
8
5
3
4
5
9
6
7
8
9

Then it essentially becomes a funky sort scenario...assuming that the low values and their duplicates always come before the high ones...

Hi.

Observations, comments.
This was a wrong assertion on my part. The tac ... tac still saves all the lines in memory (except duplicates).

@shamrock:
I am confused by your comment:
in my solution the line numbers are added specifically so that the ordering is preserved, as the OP requested. Do you have a non-memory solution that does not do something like that?

Best wishes ... cheers, drl

That means that the input data posted by "MadeInGermany" has a pattern...the low values and their duplicates always come before the high values and their duplicates...like the last "2" is far away from the first "2" but still comes before the last "3"...and since the OP requested that (s)he needs only the last of the dupes so the final output will come out sorted...

Code:

2
3
2
8
5
3

No I don't...as there is nothing like a non-memory solution in the computing world...data to be processed on disk is first brought into memory before it can be worked on...firstly because the mpu can only address data that is in memory and not on disk and secondly because the operations would be very slow...

Hi, Shamrock.

I think the OP meant that the last value of the duplicates was important because of the position in the file, not because it had some other magical properties, after all, they are duplicates.

When I wrote about memory, I was referring to all the solutions that kept all of the data in an array (except for the duplicates of course). My solution was different in that nothing was kept in arrays like that, everything was pipelined, so that there would be little or no risk of running out of memory (say with awk's arrays).

Does this makes my comments more clear? ... cheers, drl