Cannot open /dev/ttyUSB0: Permission denied

[[e-mail]]

OS: Ubuntu 12.04 LTS Beta 64 bit
Program gtkterm
Version 3.3.0
Expected: Under Ubuntu 11.10 I could just run gtkterm and select the "/dev" device as a standard user.
Probelm : Gtkterm is not able to open the /dev devices. You have to open a shell and type "sudo gtkterm" to get it to work.

[Peter Meiser (meiser79)]

Please check if you're are member of the dialout group. If not -> "sudo adduser YOUR_USER dialout" on the console

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Tom (trsaunders)]

I am having the same problem. Adding my user to dialout did not help. Of course I can create a udev rule for the device, but I didn't need to do this in previous versions of Ubuntu.

[Wade Matthews (sungreentree)]

Same: Last week I switched to Ubuntu 12.04 LTS 64 bit. Now my user can't access the serial ports. It affects not just gtkterm but other serial port programs as well. I didn't see this in prior Ubuntu versions. Adding my user to the dialout group made no difference. For now, I am running "sudo gtkterm" to get around

[psolyca (damien-gaignon)]

Same with Ubuntu 12.04 LTS 64 bit and minicom.
I have to use "sudo minicom" to connect to it.

[fulvio mingozzi (fulvio-mingozzi)]

It works, but you have to change permission to the groups. Here the full commands:

sudo adduser MyUser dialout
sudo chmod a+rw /dev/ttyUSB0

Next boot USB0 retained these permissions:

crw-rw---- 1 root dialout 188, 0 Jul 6 10:29 /dev/ttyUSB0

and so it is possible to run minicom from MyUser.

[Roger Davis (rogerdavis-d)]

I get the following errors using efax-gtk
----------------------------
Socket running on port 9900
efax-0.9a: 01:37:33 failed page /home/roger/Documents/Libre Office/Saddleback Labs Request.pdf.001
efax-0.9a: 01:37:33 finished - unrecoverable error
efax-0.9a: 01:37:33 Error: can't open serial port /dev/ttyS1: Permission denied
-------------------
The suggestions above do not fix this!

[Javier Velador (kute102fm)]

Simply adding yourself to the dialout group and opening up another terminal window will not suffice. One quick test is

add yourself to the group as described above

 # sudo adduser youracct dialout
 $ su - youracct
 $ minicom -D /dev/ttyUSB0

If this works, just close your desktop or login session and re-login/

[Manolis Kapernaros (kapcom01)]

It is not enough to add the user to dialout. You also have to sudo apt-get remove modemmanager
Check this: http://askubuntu.com/questions/133235/how-do-i-allow-non-root-access-to-ttyusb0-on-12-04
and this: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/662881

I'm using ubuntu 13.04 by the way.