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My system is Ubuntu 13.04 and works fine, but I had to installed VirtuaBox to guest Windows XP which is essential tu run an application that dialogues with an alarm set by a USB-to-Serial adapter.

VirtualBox uses ttyS0 as Serial port and the communication can start efficiently only if command sudo chmod 666 /dev/ttyS0 is given to Terminal.

Every time I boot Ubuntu, ttyS0 file permissions return to default values and I have to run chmod every time I boot-up.

My question is: how can I change /dev/ttyS0 file permission permanently? If this is not a good practice, are there other manners to solve the issue?

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1 Answer 1

There's no need to change system file's permissions. The serial devices have the following default permissions:

crw-rw---- 1 root dialout ... /dev/ttyS0

So all you have to do is add the user to the dialout group:

sudo adduser $USER dialout
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Thanks Eric, your solution worked for me after rebooting! Claudio :) –  Claudio Nov 12 '13 at 7:36
reboot is not required, re-login es enough. if you don't want to close your session you can also do ssh $USER@localhost (if you have openssh-server installed) and use that terminal. –  rrosa Oct 20 '14 at 13:45

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