Courtesy of this stackoverflow answer (and that via http://bloggernitin.blogspot.com/2007/12/regex-for-doesnt-contain.html), how to match for string not containing another string:
^((?!my string).)*$
Courtesy of this stackoverflow answer (and that via http://bloggernitin.blogspot.com/2007/12/regex-for-doesnt-contain.html), how to match for string not containing another string:
^((?!my string).)*$