index
index - find a substring within a string
index STR,SUBSTR,POSITION
index STR,SUBSTR
Returns the position of the first occurrence of SUBSTR in STR at or after
POSITION. If POSITION is omitted, starts searching from the beginning of
the string. The return value is based at 0 (or whatever you've set the $[
variable to--but don't do that). If the substring is not found, returns
one less than the base, ordinarily -1.