PC Recycler

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.
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grep ^dialout: /usr/lib/group |sudo tee -a /etc/group
 
Now we are able to add ourselves to the dialout group!
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sudo gpasswd -a ${USER} dialout
 
Activate that group in our current shell.
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newgrp dialout
 
And now we can use a tool like screen to talk to the device (note you will have needed to install screen with rpm-ostree and rebooted first).
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screen /dev/ttyUSB0 115200