With both apologies and thanks to Magic Banana, yesterday I set about to find
an independent solution
within which I can follow the logic.
Here is the series of scripts that accomplish the stated task. They are based
on the previously
attached PTRListSort.txt and IPv4.May2020.37.nMapoG.txt as illustrative data.
The first script makes the 42 files that will hold the multi-address PTR's
and their IPv4 addresses:
awk '{print $1,$2}' 'PTRList.txt' | awk '{print "touch
CountsFiles/"$1"."$2".txt ;"}' '-' > Script.MakeFiles.txt
The second script makes 42 additional files, each one ready to contain just
one PTR:
awk '{print $1,$2}' 'PTRList.txt' | awk '{print "touch PTR-files/"$1".txt ;
"}' > Script.MakePTR-files.txt
The third script writes the PTR names into their just-created files:
awk '{print "echo "$1}' 'PTRList.txt' > Temp0718A.txt ;
awk '{print " > PTR-files/"$1".txt ;"}' 'PTRList.txt' > Temp0718B.txt ;
paste -d ' ' Temp0718A.txt Temp0718B.txt > Script.Fill.PTR-files.txt ; rm
Temp0718A.txt Temp0718B.txt
The fourth script creates and lists 42 individual scripts, each one of which
collects and writes the joined
address data to its just created file. Note that the first file in the join
command contains only one line:
awk '{print "join -a 1
