I use Arduino IDE 1.6.6 on Ubuntu 15.10.

Starting the Arduino IDE without using sudo fails for both:

  • uploading the code to the Arduino Uno
  • starting the serial monitor

The group I need to add my user to is called dialout:

myuser@mycomputer:~$ ls -l /dev/ttyACM*
crw-rw---- 1 root dialout 166, 0 Dez 12 17:57 /dev/ttyACM0

So I added myuser to dialout:

sudo usermod -a -G dialout myuser

Somewhere I read that I have to add myuser to tty as well, so I did it:

sudo usermod -a -G tty myuser

Though I still fail with the above mentioned when trying to use the IDE with myuser.

What do I have to do to get the IDE working with myuser?

  • 2
    Have you logged out yet? Dec 12, 2015 at 23:26
  • 1
    @IgnacioVazquez-Abrams Oh, that was it. I had to log off and on again, something I rarely do. I feel so stupid now for not having tried that. Thanks for telling me!
    – Socrates
    Dec 12, 2015 at 23:55

1 Answer 1


There should be a command like 'id' or something similar that will show the groups you are a member of. Run that to check that the new groups have taken effect – you may need to log out and then log back in.

The other thing to check is the group owner of the device itself (in /dev). that will also need to match the group you assigned to yourself. Also make sure that the device permissions allow group access.

  • This is a very informal "solution", not too useful for beginners.
    – snorbi
    Mar 3, 2023 at 9:50

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