I thing we live in an era that foss land is attacked. Not exactly the whole word . One letter is attacked.
For me the attack was formely initiated the day RMS visited Redmond (what was on his mind??...) .
Days letter the web lynching of RMS started. Paidophile, autistic , dirty bearfoot hippy..etc.

The great irony?. The MIT scandal raised serious ethical questions about funding from malicious and unethical actors to institutions
that we prefer to envision as public and motivated by higher ideas. Education,  knowledge etc.

But the second greatest irony? Many Institutions in the foss land (SFC,Redhad,FSFE) aligned with MIT's heads  scapegoating agenda saw that as an opportunity
not to discuss the matter of ethical donatiions but disgracing publicly  RMS persona announcing to the plubs the new inclusive order of things.

In that new era.. Linus and Richard are in the social dysfunctional spectrum and in foss fora the new ideas of sponsor hunting and corporate friendliness have taken the sky..

HUGE piles of money (huge propably in our eyes for a big corp propably one medium scale strategy campaing.. for those uninitiated a study of how Uber conducts those affairs should be a good start up tutorial...)  and donations from SFC to OpenBSD  and Gnome have  been softening  the ground to let the new order bloosom.

Foss Newsites call us to be thankfull to our benovalent new masters in the fossland.

Thank you.
I've created an installation video . I'll use that hint in future versions.

Interestingly invocation section of man page of bash dont refer to profile.d .
So maybe it started as a distro practice that stuck  and now it's used a a global config-set up space ?
I found an interesting discussion here.

It seems that profile.d is used in some distros that use some shells that parse that folder for application specifics setups.

In my devuan installation:

/etc/profile.d$ ls
bash_completion.sh       flatpak.sh  gawk.sh      vte.csh  gawk.csh    vte-2.91.sh

But that wont work in a case like mine but only if libvirtd was reading some shell enviroment
variable to determine what net setup to enable when started.

So i guess profile.d is one way to setup an 'enviroment' for applications that would look to certain env variables.
If an app looks only to a config file profile.d it's not needed.

In my case i found first here  about a command that fixes
a network error in virt-manager. Now as @xinomilo told me that can be set either with a terminal command or a gui setting   that changes a relative setting.

I propably was unlucky finding only the first 'solution'  that make me understand that a command fixes an error . But now it seems it's just an application
setting that propably sitting in a config file and there are two ways to change that 'file' and propably to edit it by a text editor.
And maybe virt-manager shouldnt either report it as an error! That small detail could have put me into a different fix mentality and not in the 'config' mentality.

To sum it up. It was a setting issue masqueraded as a  pseudo 'correct functioning' issue.

Reading here https://www.linuxfromscratch.org/blfs/v … ofile.html
it seems that profile.d is for scripts that set up the shell enviroments.
So if i wanted to setup an application and it's initial set up i should do it from somewhere else.
But i've just read an askubuntu post where network config is attempted from a profile.d script.

That explains why other scripts in profile.d werent executable.

Generaly i realized that profile.d is for preparing the system wide enviroment (of bash only or more generally ?)
So a more sound approach would be to start libvirtd and then make sure the default networking is enabled .

I made it executable but still nothing.

The test var is changed but not the net default state.
I suspect that virt-manager and libvirtd process must have started first.

I know it's purpose, not familiar but i'll manage.

I tried that so far:

$ less /etc/profile.d/enableqemunetworking.sh
#!/bin/sh
virsh net-start default   &

but didnt work..
@HeadonStick i try to enable qemu networking but the command only works with sudo.

Ok. so i'll keep xscreensaver for now .

$ aptitude why xscreensaver
i   task-xfce-desktop Depends    xfce4                               
i A xfce4             Depends    xfce4-session (>= 4.16.0)           
i A xfce4-session     Recommends xscreensaver | light-locker | i3lock

Thanks for the reply.