Instead of using a password manager to store your passwords, this eliminates the need to store passwords entirely.

!/bin/bash

echo -n "Enter your salt (won't be displayed): "
read -s SALT
echo -en "\n"
echo -n "Enter your string: "
read STRING
echo -n "Your password is: "
PASSWORD=$(echo -n "$SALT$STRING" | sha512sum | base64 -w 0)
echo ${PASSWORD:32:32}
exit 0;