#! /bin/bash

printf "Filepath: "
read fpath
printf "Number of lines to trim from the head: "
read htrim
printf "Number of lines to trim from the tail: "
read ttrim
printf "\n"

n=$(wc -l "$fpath" | awk '{ print $1 }')

hls=$(($n-$htrim))
tls=$(($hls-$ttrim))

tail -n "$hls" -r "$fpath" | tail -n "$tls" -r | awk '!(NR%2){print$0"\t"p}{p=$0}END{print "Total: \t"NR}' > "$fpath"-xformed

cat "$fpath"-xformed