Looks like you’re on Fedora Silverblue (or other Atomic version). This is happening because the system groups are in /usr/lib/group rather than /etc/group and this causes the issue you’re seeing here. You can work around it by getting into a root shell with something like
sudo -i
and then getting the group added to /etc/group with
grep -E '^dialout' /usr/lib/group >> /etc/group
after that, you’ll be able to add your user to the group with
Looks like you’re on Fedora Silverblue (or other Atomic version). This is happening because the system groups are in /usr/lib/group rather than /etc/group and this causes the issue you’re seeing here. You can work around it by getting into a root shell with something like
sudo -i
and then getting the group added to /etc/group with
grep -E '^dialout' /usr/lib/group >> /etc/group
after that, you’ll be able to add your user to the group with
usermod -aG dialout pipe
Is that considered a feature for some reason? That seems objectively terrible.
No, it’s a side effect of how everything’s handled by rpm-ostree currently, and it’s on the list of issues to be fixed.
See Here for more info