#1

I’m on SB 31, and I can’t access /dev/ttyACM0 from inside the toolbox container.

My user is a member of dialout (on the host and in the container).

I think the problem is that in the container the owner/group of /dev/ttyACM0 is nobody.

On the host:

$ ls -al /dev/ttyAC*
crw-rw----. 1 root dialout 166, 0 Dec 15 15:35 /dev/ttyACM0
crw-rw----. 1 root dialout 166, 1 Dec 15 15:37 /dev/ttyACM1

In the container:

$ ls -al /dev/ttyAC*
crw-rw----. 1 nobody   nobody 166,  0 Dec 15 15:35 /dev/ttyACM0
crw-rw----. 1 nobody   nobody 166,  1 Dec 15 15:37 /dev/ttyACM1
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#2

How are you starting the container?
Is it a rooted or rootless container?
How are you passing the device through?

#3

Sorry didn’t spot you’re using toolbox…

You will need to change the perms on the device, if as an example, you have something like fred:100000:65536 in your /etc/subgid file then dialout which has a GID of 18 in the container will map to something like 1000018 outside the container. Something along the lines of:
sudo setfacl -m g:100018:rw /dev/ttyACM0
on the host should allow the dialout group in the container access to the device, this ACL will not survive a reboot so you will want to setup a udev rule to add it when the device node is created.

To identify the correct group id, in the container run:
sg dialout -c ‘sleep 1000’
then on the host run:
ps -eo “user,group,args” | grep sleep
this should show the UID and GID of the process.

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Permission error to dd USB from Toolbox