On Friday, 3 October 2025 23:01:07 British Summer Time Javier Martinez wrote: > El 3/10/25 a las 23:42, Markus Gustafsson escribió: > > > Evening! > > > > Tonight I've been trying to get an RTL-SDR dongle working using this wiki > > article: https://wiki.gentoo.org/wiki/Rtl-sdr > > I set up everything according to the article, and then tried to run > > 'rtl_test'. This worked fine as root, but not as my regular user. It gave > > me the following error message: > > > >> $ rtl_test > >> Found 1 device(s): > >> 0: �+.B�, , SN: > >> > >> > >> > >> Using device 0: Generic RTL2832U OEM > >> usb_open error -3 > >> Please fix the device permissions, e.g. by installing the udev rules file > >> rtl-sdr.rules Failed to open rtlsdr device #0. > > > > > > This is despite having added my user to the 'sdr' group. I googled around, > > but couldn't figure anything out (everybody else seems to forget about > > the udev rule, but I didn't). Then I did the following: > > > >> $ ls -la /dev/rtl_sdr > >> lrwxrwxrwx 1 root root 15 Oct 3 23:19 /dev/rtl_sdr -> bus/usb/001/010 > >> $ ls -la /dev/bus/usb/001/010 > >> crw-rw---- 1 root plugdev 189, 9 Oct 3 23:19 /dev/bus/usb/001/010 > > > > > > So for some reason the group is 'plugdev'. When I added my user to that > > group everything works fine, but I don't understand why it gets added to > > that group? Is there some kind of conflict going on here? The udev rule > > from the article is the only udev rule I have (at least in > > /etc/udev/rules.d).
Gentoo uses the group plugdev to elevate privileges in order for plain users
to be able to operate on USB devices. The sdr group which the wiki page
recommends would work, if only the ebuild had created it.
> > Mvh,
> > Markus
> >
> >
>
> Probably the some reason is policykit
I see the ebuild mentions a group account "usb" instead of plugdev. Perhaps
it should contain a different post install message than this mentioning
plugdev instead:
===================
[snip ...]
pkg_postinst() {
udev_reload
elog "Only users in the usb group can capture."
elog "Just run 'gpasswd -a <USER> usb', then have <USER> re-login."
}
=====================
I recall the usb group was used with eudev, but I don't know if it is still
valid.
Marcus, you could file a bug report to ask for the rtl-sdr and rtl-sdr-blog
ebuilds to mention pludev. Also the wiki page will need editing to reflect
current status.
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