How to find the length of a string in Linux/Unix Shell scripting

While writing a shell script you might want to find the length of a string. While reading GNU expr command man page I found an interesting option:

expr length STRING

For example display the length of "abusittik" word:
expr length "abusittik"

Output:
9

expr and POSIX

However expr command is not concerned with POSIX (open system standards based on Unix). You can try old good KSH/Bash command (also following command should work with other UNIX like OSes such as FreeBSD / Solaris ):

myVar="abusittik"
echo ${#myVar}

Output:
9

Using AWK :

% echo abusittik | awk ‘ { print length } ‘

Output : 9

Using Perl:
 % echo abusittik | perl -nle ‘ print length ‘

Output : 9