Let’s consider an input text file like this:

```
some text …
% BEGIN
blabla
foo bar
blabla
blabla
% END
some text …

```

and a `foobar.txt` file like this:

```
2 3
8 9 
1 2

```

what is the simplest way using `sed` (maybe `awk` ?) to obtain this output text file:

```
some text …
% BEGIN
blabla
2 3
blabla
blabla
% END
% BEGIN
blabla
8 9
blabla
blabla
% END
% BEGIN
blabla
1 2
blabla
blabla
% END
some text …

```