To do that I used the following code, but it doesn't work:

Doesn't work how? It certainly won't make the change you suggest because it seems you are just trying to add some quotes and an extra slash... but even that is failing because

my $endUnixLine =~ s|\/apost.|"//apost."|g;

is trying to do the substitution on a newly declared variable. If you were running with warnings on, perl would have barked at you about that.

If you are having trouble with the regular expression to use, you might help us to help you (and you might help yourself) by providing a better specification of what you actually need to do.

-sauoq
"My two cents aren't worth a dime.";