Replace delimited block of text in file with the contents of another file

Question

I need to write a simple script to replace a block of text in a configuration file with the contents of another file.

Let\'s assume with have the following simplifie

Answer 1

I was unable to get Dennis solution easily working on OS X (its BSD sed is slightly different). I found this other solution that I was able to make work on both Linux and OS X (I have a mixed environment). The original version on superuser.com works only on Linux, here I fixed it:

lead='^$'
tail='^'
sed  -e '/'"$lead"'/,/'"$tail"'/{ /'"$lead"'/{p; r realm.xml' -e' }; /'"$tail"'/p; d;} '  server.xml

Here a version of Dennis code that works also on OS X (using multiple lines):

sed -ne '/'"$lead"'/ {
 p
 r realm.xml
 :a
 n 
 /'"$tail"'/ {
  p
  b
 } 
 ba
 }
p' server.xml

Both these codes print the output on stdout. Use redirection or, to substitute the file inline, add the option '-i' (on linux) or '-i ""' (on BSD/OS X).