awk-insert row with specific text within specific position - text

Question

I have a file where the first couple of rows start with # mark, then follow the classical netlist, where also can be there rows begin with # mark. I need to insert one row with text protect between block of first rows begining on # and first row of classical netlist. In the end of file i need insert row with word unprotect. It will be good to save this modified text to new file with specific name because of the original file protected.
Sample file:
// Generated for: spectre
// Design library name: Kovi
// Design cell name: T_Line
// Design view name: schematic
simulator lang=spectre
global 0
parameters frequency=3.8G Zo=250
// Library name: Kovi
// Cell name: T_Line
// View name: schematic
T8 (7 0 6 0) tline z0=Zo f=3.8G nl=0.5 vel=1
T7 (net034 0 net062 0) tline z0=Zo f=3.8G nl=0.5 vel=1
T5 (net021 0 4 0) tline z0=Zo f=3.8G nl=0.5 vel=1
T4 (net019 0 2 0) tline z0=Zo f=3.8G nl=0.5 vel=1

Answer 1

How about sed
sed -e '/^#/,/^#/!iprotect'$'\n''$aunprotect'$'\n' input_file > new_file
Inserts 'protect' on a line by itself after the first block of commented lines, then adds 'unprotect' at the end.
Note: Because I use $'\n' in place of literal newline bash is assumed as the shell.

Answer 2

Since you awk'd the post
awk 'BEGIN{ protected=""} { if($0 !~ /#/ && !protected){ protected="1"; print "protect";} print $0}END{print "unprotect";}' input_file > output_file
As soon a row is detected without # as the first non-whitespace character, it will output a line with protect. At the end it will output a line for unprotect.
Test file
#
#
#
#Preceded by a tab
begin protect
#
before unprotect
Result
#
#
#
#Preceded by tab
protect
begin protect
#
before unprotect
unprotect
Edit:
Removed the [:space:]* as it seems that is already handled by default.
Support //
If you wanted to support both # and // in the same script, the regex portion would change to /#|\//. The special character / has to be escaped by using \.
This would check for at least one /.
Adding a quantifier {2} will match // exactly: /#|\/{2}/