$>expr index 'abcdef' 'b'
2
$>expr index 'abcdef' 'be'
2
$>expr index 'abcdef' 'ca'
1
$>expr index 'abcdef' 'dq'
4
$>expr index 'abcdef' '12'
0
#index string character-list
#Return the first position in string that matches the first possible character in character-list. Continue through character-list until a match is found, or return 0.
