modify a datastream on the fly

Question

I need to hijack and modify a datastream. The stream consists of fixed-width commands. Each command is a new line, and the documentation says that each command starts and ends

Answer 1

Instead of the sed command, you can use this:

perl -pe 's/(,\w+)/" " x length $1/ge'

The e option on the substitution means that the right side of the s/// is evaluated as a Perl expression. In this case, the expression returns the correct number of spaces, based on the length of the captured match.