Sed substitution possible with arithmetic involved?

Question

File I need to modify contains the following:

block: 16, size: 16, start: 8, length: 4

I\'d like the file so that values for block<

Answer 1

Perl is useful here:

perl -pe '
  s{(\D+)(\d+)(\D+)(\d+)(\D+)(\d+)(\D+)(\d+)}
   {$1 . $2/2 . $3 . $4/2 . $5 . $6*2 . $7 . $8*2}e
' file

If you want to edit your files in-place, perl has a -i option like sed.