script-options

use getopts, for example;

#!/bin/bash

if [ $# -lt 6 ] # we expect 6 options, 1 for each switch and 1 for each value
then
        echo "Usage: $0 -v vhost -u user -c cluster" >&2
        exit 1
fi

# get arguments
vhost=  user= cluster=

while getopts v:u:c: opt
do
        case $opt in
        v)      vhost=$OPTARG
                ;;
        c)      cluster=$OPTARG
                ;;
        u)      user=$OPTARG
                ;;
        '?')    echo "$0: invalid option -$OPTARG" >&2
                echo "Usage: $0 -v vhost -u user -c cluster" >&2
                exit 1
                ;;
        esac
done

shift $((OPTIND -1))

# generate password of passed length
...