Bugfix: qsu and qssh create a shell script file to echoing the password. If the password contains special letters, e.g. test$1, then the password must be set in single quotes.
Compatibility: the generated script file will work with each sh. The bash is possible but not a must have.
Optimization: Added some checks for missing arguments
Optimization: Sets the generated script files read/write/execute rights only for the user, not for all. I suppose reading the password is better limited. I hope no system needs wide access rights for the SUDO_ASKPASS command file.