Shell Script to Multiply Lines and add the Sum

Question

 Thanks all for the inputs but now i landed up in another problem .

  This is my Orginal syntax 

   db2 list tablespaces show detail | grep -e " Free pages" -e " Page size"
   Free pages                           = Not applicable
 Page size (bytes)                    = 4096
 Free pages                           = Not applicable
    Page size (bytes)                    = 4096
  Free pages                           = Not applicable
  Page size (bytes)                    = 4096
   Free pages                           = 36960
    Page size (bytes)                    = 32768
  Free pages                           = 40800
 Page size (bytes)                    = 16384
  Free pages                           = 22656
   Page size (bytes)                    = 4096
  Free pages                           = Not applicable
      Page size (bytes)                    = 4096

      Now if i see Not applicable then i should remove Not applicable line and as well as the proceeding line for that i used the below syntax 

  db2 list tablespaces show detail | grep -e " Free pages" -e " Page size"  | awk '/Not/{getline;next} 1'

  Free pages                           = 36960
 Page size (bytes)                    = 32768
 Free pages                           = 40800
  Page size (bytes)                    = 16384
 Free pages                           = 22656
 Page size (bytes)                    = 4096

But i am not sure why the last 4096 is comming for me in the output ??

and then i need to remove the (bytes) as well and print only the value so i used the below syntax

 db2 list tablespaces show detail | grep -e " Free pages" -e " Page size"  | awk '/Not/{getline;next} 1' | sed 's/(bytes)//g' | awk '{print$4}'

36960 32768 40800 16384 22656 4096

and i forgot to mention that with respect to my first posting (My question is i want to multiply line 1 to line 2 then line 3 to line 4 and line 5 to line 6 as goes on till the end of the output and finally add the whole sum )

in the second line , fourth line and sixth line i need to take only the first 2 charchater and then multiply

Like below

36960 * 32 40800 * 16 and goes on from that i need the value in the GB by dividing by 1024 and 1024 again as the orginal value is in KB

                 I know i am asking too much but can some one help ??
                     Waiting for some reply .. Thanks

Answer 1

For a bash shell script:

#!/bin/bash
TOTAL=0
while read A && read B; do
    (( TOTAL += A * B ))"
done
echo "Total: $(( TOTAL / 1024 / 1024 )) GB"

Then run:

bash script.sh < input_file

The concept should be easy to convert if you want it to be usable across many types of shell. Just consider the command bc and other similar tools probably.