Clarify: SEARCH AND replace between <TAG> </TAG>

Sorry I wasn't clear. I need to search for the <TAG></TAG> combo in an html file. Thats why I asked for a regex. So I need to load in the html SEARCH for the tags and anything in between the tags throw out and REPLACE with the contents of a variable and then rewrite the file. My orginal message follows: > I've been trying this one for a bit and Im in a twist. > > I need to replace ANYTHING or even nothing between two tags > with the contents of a variable and just havent been > able to get the expression right for all cases. > > > As an example concept follows: > > <TAG></TAG> > > Nothing between the tags variable is $varname="some junk" > > so after the function > <TAG>some junk</TAG> > > run it again after making variable $varname="some completly different junk" > > so now the tags would be > > <TAG>some completly different junk</TAG> > > and so on and so on..... > > One other breaker Ive had, it needs to always replace no matter whats > between the tags, whats not between the tags or even if its 1000s of > characters. My code kept breaking when it was alot of characters. > > Any funtions or even just the right regex would be appreciated > > Thanks