A question about subprocess taking input from command line and returning output!

[Aurimas]

Thank you guys, but I want to specify what pdb file I choose to use (like 1abc.pdb, 1fgh.pdb or other) and the output I need is

awk '{sum += $3} END {print sum}'

that prints a numerical value to terminal. Full terminal command in linux/mac would be

cat HS_1abc.pdb | voronota get-balls-from-atoms-file --annotated | voronota calculate-contacts --annotated | voronota query-contacts --inter-residue --match-first 'R<ARG>' --match-second 'c<solvent>' | awk '{sum += $3} END {print sum}'

I also need the program to say what R in --match-second to use (in this case it is ARG but it can have any one of 20 different values). Also for --match-second I need to define up to fours values like c<A,B,C,D>, c<A,B), c<W,C>, c<solvent>, c<A,C,E> or other letters

How could that be possible with pipes and subprocess and communicate?