One of the things I do a lot on my Fedora machines is talk to devices via USB serial. While a device is correctly detected at /dev/ttyUSB0 and owned by the dialout group, adding myself to that group doesn’t work as it can’t be found. This is because under Silverblue, there are two different group files (/usr/lib/group and /etc/group) with different content.
There are some easy ways to solve this, for example we can create the matching dialout group or write a udev rule. Let’s take a look!
On the host with groups
If you try to add yourself to the dialout group it will fail.
sudo gpasswd -a ${USER} dialout
gpasswd: group 'dialout' does not exist in /etc/group
Trying to re-create the group will also fail as it’s already in use.
sudo groupadd dialout -r -g 18 groupadd: GID '18' already exists
So instead, we can simply grab the entry from the OS group file and add it to /etc/group ourselves.
grep ^dialout: /usr/lib/group |sudo tee -a /etc/group
Now we are able to add ourselves to the dialout group!
Continue reading Accessing USB serial devices in Fedora Silverblue