Re: Apparently irrational behaviour in sort

[Andreas Schwab]

The Wanderer <address@hidden> writes:

> I have a text file whose lines each contain two dates, of the format
> "MM-DD-YYYY". I want to sort these lines into order from oldest to most
> recent - that is, first by YYYY, then by MM, then by DD. After I parse
> out the spaces using sed, the only whitespace remaining in the file is
> the blocks of contiguous tabs which I use to divide the columns which
> contain the actual data; the date I want to sort on is in the fifth such
> column, which should at that point be field number 5.
>
> I would expect that 'sort -k 5.7,5 -k 5,5' would sort first by the
> seventh character in the fifth field (the first digit of the year), thus
> putting the file in order by year, and then by the entirety of the fifth
> field, thus putting the file in order by month and day. It does not.

This is because the whitespace between the fields belongs to the following
field, ie. the field boundary is the point between a non-whitespace and a
whitespace character.  Thus you either have to increase the offset by the
number of whitespace characters at the start of the field (if it is
consistent), or use the b flag to skip whitespace altogether.

Andreas.

-- 
Andreas Schwab, SuSE Labs, address@hidden
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
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