How to (in a shell script) get the position of a substring that contains double quotes?

Question

I have a very long string and I want to find the first occurrence of a substring - but the substring contains double quotes. The only way of doing this that I'm familiar with is:

mystr='a very, very, extremely, incredibly long string of text that contains the phrase he said, "Hello!" somewhere in the middle'
strpos=`expr index "$mystr" Hello`
echo $strpos

which returns 92. But that won't work if the substring contains double quotes...

strpos=`expr index "$mystr" he said, "Hello`

I've tried escaping the double quotes (and the spaces). I've tried wrapping the string to find with single quotes. If I manage to run it without getting "unexpected EOF" or "syntax error", it returns a preposterous result like "2". (The position is somewhere in the thousands.) I'm guessing that I can't do what I'm trying to do with expr index but if not, then how can I do it?

Answer 1

I think that it searches for characters of second string in first one. You can use grep

mystr='a very, very, extremely, incredibly long string of text that contains 2 the phrase he said, "Hello!" somewhere in the middle'
echo "$mystr"| grep -o -b Hello!

It will return 91:Hello!. Here indexing starts from 0.

If there are multiple occurrences like of a, then output will be

0:a 58:a 65:a 77:a 85:a

If you want to search double quotes too, then escape them,

echo "$mystr"| grep -o -b \"Hello!\"

The output will be

90:"Hello!"

Answer 2

Only with Parameter Expansion :

mystr='a very, very, extremely, incredibly long string of text that contains the phrase he said, "Hello!" somewhere in the middle'  
searchstr='"Hello!"'
newstr="${mystr%%$searchstr*}"
echo "position = $((${#newstr} + 1))"

Answer 3

Let's see if this is what you are looking for:

mystr='a very, very, extremely, incredibly long string of text that contains the phrase he said, "Hello!" somewhere in the middle'

$ var=$(echo "$mystr" | grep -o -b "Hello!" | head -1)
$ echo "$var"
91:Hello!
$ pos="${var%:*}"
$ echo "$pos"
91