#!/bin/bash

for uid in $(wp-cli --allow-root user list --field=user_login)
do
        pass=`< /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c${1:-32}`
        wp-cli --allow-root user update $uid --user_pass="$pass"
        echo Username: "$uid"
        echo New password: "$pass"
done