Red Hat / Fedora :: Define User /password For Sasl?

I need define a user /password for sasl but want the authentication at runtime be automatic - no explicit prompting the user while accessing a tcp socket with some applications that need the authentication (e.g libvirt)

so I try : saslpasswd2 -c -p -a libvirt <user>

and it hangs (if i now press Enter it says : "invalid parameter supplied") . if I avoid the -p flag the above commad works fine and prompts for password and later when using the tcp it prompts for the above defined user/password and autheticates ok .
But I want without the explicit authentication

The man pages says -p Pipe mode - saslpasswd2 will neither prompt for the password nor verify that it was entered correctly. This is the default when standard input is not a terminal.

In the past (before some upgrading of libvirt via rpm) I had the SASL authentication at runtime done automatically with no explicit prompting the user