Re: coreutils feature requests?

[Lance E Sloan]

Hi, Berny.

You've beaten me to the punch. I have another message draft in progress
about join. I'll send it later.

I haven't compared join with cut and awk, but it does the job.

On Wed, Jul 19, 2017 at 17:08 Bernhard Voelker <address@hidden>
wrote:

> On 07/19/2017 07:43 PM, Kaz Kylheku (Coreutils) wrote:
> > It is nontrivial code. For instance if we look at how the function
> > cut_bytes works in the implementation, what it's doing is simply
> > doing a getchar() from the stream, and querying a data structure
> > to determine whether the byte should be printed or not.
> > (That data structure consists of a pointer which marches through
> > field range descriptors in parallel with going through the data.)
> >
> > cut_fields is more complicated due to the delimiting of fields,
> > but essentially the same overall approach.
> >
> > Basically, printing of fields that isn't sorted and de-duplicated
> > is a rewrite of all parts of the utility other than command
> > line processing and the printing of usage help text.
> >
> > It's like two different programs in one, sharing a minimal
> > skeleton.
>
> +1
>
> Another point: it is already documented that cut(1) output is
> never good for reordering:
>
>
> http://git.sv.gnu.org/cgit/coreutils.git/tree/doc/coreutils.texi?id=545f181f4e#n5938
>
>   Note @command{awk} supports more sophisticated field processing,
>   like reordering fields, and handling fields aligned with blank
> characters.
>   By default @command{awk} uses (and discards) runs of blank characters
>   to separate fields, and ignores leading and trailing blanks.
>   @example
>   @verbatim
>   awk '{print $2}'      # print the second field
>   awk '{print $(NF-1)}' # print the penultimate field
>   awk '{print $2,$1}'   # reorder the first two fields
>   @end verbatim
>   @end example
>   Note while @command{cut} accepts field specifications in
>   arbitrary order, output is always in the order encountered in the file.
>
> and even more: it suggests to use join:
>
>   In the unlikely event that @command{awk} is unavailable,
>   one can use the @command{join} command, to process blank
>   characters as @command{awk} does above.
>   @example
>   @verbatim
>   join -a1 -o 1.2     - /dev/null # print the second field
>   join -a1 -o 1.2,1.1 - /dev/null # reorder the first two fields
>   @end verbatim
>   @end example
>
> Is this sufficient?
>
> Have a nice day,
> Berny
>