in reply to Re^4: How to print certain lines out of a text file.
in thread How to print certain lines out of a text file.

You can use the range operator on the command line, like so:
perl -ne "print if m{^\s*HW/OS/Client:} ... m{^\s*$}" mas01_policy_dum +p.txt

which tells Perl to go through every line of the given file and print lines in-between (inclusive) two lines which match: