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.

Glad to help.

Ok, finally i managed to send the bugreport to debian by :
$ reportbug --bts debian
https://bugs.debian.org/cgi-bin/bugrepo … ug=1003831

But i think it would be more user friendly :-)  reportbug to handle that , because now the sender must
crosscheck for if the package s(he) reports for is unforked and imported from debian