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Author Topic: USB Permissions tip  (Read 5890 times)

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February 14, 2011, 08:41:04 am
If, like me, you use a usb->serial ttl adaptor, you might find that Linux gets a bit finicky about the permissions on /dev/ttyUSB and randomly changes them at inopportune times.

If you have that happen to you, try adding your user id to the uucp group.

First, find out your current username with the cunningly named whoami utility.


Code: [Select]
#whoami

mrexampleuser


Know we know our username (mrexampleuser in the example above), we can add ourselves to the uucp group.

Why the uucp group?
History.

These days, its mostly because uDev adds serial ports with that group.

Code: [Select]
grep serial -A1 /etc/udev/rules.d/50-udev-default.rules

# serial
KERNEL=="tty[A-Z]*|pppox*|ircomm*|noz*", GROUP="uucp", MODE="0666"

So... to cut a long story short, add yourself to the uucp group, and you'll be back on track.
Lets do that for our user called mrexampleuser

Code: [Select]
sudo usermod -G uucp mrexampleuser