Strange. Why invoke sed out of a Perl script to do a job Perl is perfectly capable to do itself? I also see a lot of horribly named $tempfoo variables that have nothing to do with the system call in question, but no indication as to where $search, $replace, $File1, and $Replace_html get populated and what kind of values they might contain.

If you want good advice, you should probably take a step back and explain to us exactly what it is you that want to do.

Makeshifts last the longest.