Shell Script: Different Method to Find Out Number of Characters in a String

To count total number of characters in a string

Count total number of

$ mystring="This is my test string"

$ echo "${#mystring}"

22

$ expr length "$mystring"

22

$ echo $mystring|awk '{print length}'

22

$ len=`echo $mystring | wc -c`;echo `expr $len - 1`

22

To count specific characters in sting.

$ grep -o "[s|S]" <<<"$mystring" | wc -l

4

$ grep -o "[ ]" <<<"$mystring" | wc -l

4

$ grep -o "[T|i]" <<<"$mystring" | wc -l

4

$ grep -o "[s|i]" <<<"$mystring" | wc -l

7