Shell Script to count the number of consonants and vowels in sentence. The sentence is supplied as command line arguments

if(( $#==0 ))
then
    echo -e "Invalid number of arguments provided"
else
    vow=0
    cons=0
    for str in $*
    do
        #len=`echo $str | wc -c`
      
        len=`expr length $str`
        for(( i=1;i<=len;i++ ))
        do
            char=`echo $str | cut -c $i`
            case $char in
                a) (( vow=vow+1 )) ;;
                A) (( vow=vow+1 )) ;;
                e) (( vow=vow+1 )) ;;
                E) (( vow=vow+1 )) ;;
                i) (( vow=vow+1 )) ;;
                I) (( vow=vow+1 )) ;;
                o) (( vow=vow+1 )) ;;
                O) (( vow=vow+1 )) ;;
                u) (( vow=vow+1 )) ;;
                U) (( vow=vow+1 )) ;;
          
                *) (( cons=cons+1 )) ;;
            esac
        done
    done
    echo -e "\t\tINPUT: $*\n"
    echo -e "\t\tNo. of Vowels=$vow\n\t\tNo. of Consonants=$cons"  
fi