Copying hashtag comments recursively within <blocks>

Question

I have two files, one with blocks like

<record>
line1
line2
line3
#model bla bla bla
</record>

while the other file has exactly the same number of blocks, but without the hashtag comments, ie like

<record>
line4
line5
line7
line8
line9
line10
</record>

So, what I want to do, is to copy from the 1st block of the first file the hashtag to the 1st block of the second file so that my other file also looks like

<record>
line4
line5
line7
line8
line9
line10
#model bla bla bla
</record>

Answer 1

If you want it in the same order small code in python

import os
os.rename("second","second~")
a=[]
f=open("first","r")
lines=f.readlines()
b=-1
for line in lines:
    if "</record>" in str(line):
        if b!=-1:
            a.append(lines[b])
        else:
            print "</record> found in first line"
    b=b+1
f.close()
b=0
destination = open("second","w")
source = open("second"+"~","r")
for line in source:
    if "</record>" in str(line):
        destination.write(a[b])
        b=b+1
    destination.write(line)
source.close()
destination.close()

note:first is the file containing the hashtag and second is the file without hashtag

Answer 2

From your sample, it looks like this simple awk command should be enough:

awk '/<\/record/{"grep \\^\\# file1"|getline a; print a};1' file2

Or, if as figured out from the further requirements exposed in the comments to the other answer which you forgot to add to your question ;-), hash tags may appear outside <record> blocks:

sed '/<record>/,/<\/record>/!d;/^#/!d' < file1 |
  awk '/<\/record/{getline a < "-"; print a};1' file2