posix sh: how to count number of occurrences in a string without using external tools?

Question

In bash, it can be done like this:

#!/bin/bash

query='bengal'
string_to_search='bengal,toyger,bengal,persian,bengal'

delimiter='|'

replace_queries="${string_to_search//"$query"/"$delimiter"}"

delimiter_count="${replace_queries//[^"$delimiter"]}"
delimiter_count="${#delimiter_count}"

echo "Found $delimiter_count occurences of \"$query\""

Output:

Found 3 occurences of "bengal"

The caveat of course is that the delimiter cannot occur in 'query' or 'string_to_search'.

In POSIX sh, string replacement is not supported. Is there a way this can be done in POSIX sh using only shell builtins?

Answer 1

Think I got it...

#!/bin/sh

query='bengal'
string_to_search='bengal,toyger,bengal,persian,bengal'

i=0
process_string="$string_to_search"
while [ -n "$process_string" ]; do
    case "$process_string" in
        *"$query"*)
            process_string="${process_string#*"$query"}"
            i="$(( i + 1 ))"
            ;;
        *)
            break
            ;;
    esac
done

echo "Found $i occurences of \"$query\""