Cannot open /dev/ttyUSB0: Permission denied

Bug #949597 reported by
This bug affects 17 people
Affects Status Importance Assigned to Milestone
gtkterm (Ubuntu)

Bug Description

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.

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Peter Meiser (meiser79) wrote :

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

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Launchpad Janitor (janitor) wrote :

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

Changed in gtkterm (Ubuntu):
status: New → Confirmed
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Tom (trsaunders) wrote :

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.

fatih yucesoy (fyucesoy)
description: updated
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Wade Matthews (sungreentree) wrote :

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

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psolyca (damien-gaignon) wrote :

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

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fulvio mingozzi (fulvio-mingozzi) wrote :

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.

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Roger Davis (rogerdavis-d) wrote :

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!

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Javier Velador (kute102fm) wrote :

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/

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Manolis Kapernaros (kapcom01) wrote :

It is not enough to add the user to dialout. You also have to sudo apt-get remove modemmanager
Check this:
and this:

I'm using ubuntu 13.04 by the way.

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