openSUSE 13.2 (Harlequin) (x86_64)
I have device connected to my PC via USB TTL Serial Adapter.
I can see it OK:
linux-zajy:/dev/serial # ls by-id
usb-1a86_USB2.0-Serial-if00-port0
linux-zajy:/dev/serial # ls by-path
pci-0000:00:02.0-usb-0:10:1.0-port0
I have installed cutecom (serial terminal) from YAST
but… when I try to connect/open device I just get error message (… could not connect…)
I have tried all different permutations, but still no good
Any ideas what am I doing wrong??
ls -l would hve been better, It will show if this is a symlink and when yes to what and you are then able to do an ls -l of that device file and show it’s permissions. When not it will show permissions directly.
Also saying “when I try to connect/open device” is not very informative. You have to see these things from thje computers interpratation side. And the computer does not know any “I”. It does know loged in users. Also it is always much, much better to not say: “When I …, Then …”, show what you did and what the computer did. Copy/paste from the terminal into a post here. Like you did with those ls commands above.
thank you for replying.
if I understand you correctly?
linux-zajy:~ # cd /dev/serial
linux-zajy:/dev/serial # ls -l
total 0
drwxr-xr-x 2 root root 60 Jun 22 13:56 by-id
drwxr-xr-x 2 root root 60 Jun 22 13:56 by-path
linux-zajy:/dev/serial #
Sorry, my description was deficient indeed.
Hopefully this is better?:
1 - start cutecom
2 - press “opendevice” key after selecting device from dropdown list
I will try the cutecom as root?
I did run cutecom and tried to open the device in cutecom
I didn’t do anything in the terminal
I tried using cutecom (serial terminal available from YAST)
In your first post you did
ls /dev/serial/by-id
I asked for
ls -l /dev/serial/by-id
And that is done in the terminal isn’t it?
So you did do something in the terminal. Though not the program cutecom. And yes, when you would have explained that it is a GUI program that would have been more informative.
As it is we still wait for the ownership and permissions of the device file as asked above. So the ls -l as asked above and when they are symlinks, then allso an ls -l of the file that they point to.
If you should run cutecom as root I do not know. The documentation should tell you. But because “never run anything as root when it is not explicetly needed” you should not do that with the idea: Oh, I can always try as root 
Now I understand ;), here it is:
linux-zajy:/home/bambuko # ls -l /dev/serial/by-id
total 0
lrwxrwxrwx 1 root root 13 Jun 22 13:56 usb-1a86_USB2.0-Serial-if00-port0 -> ../../ttyUSB0
linux-zajy:/home/bambuko #
Indeed it would - sorry for not doing it in the first place.
Thus, as explained above, we now need
ls -l /dev/ttyUSB0
That is where the symlink you show points to. And that is the “real” device file.
Never mind.
cutecom in itself runs fine either as a root or anything else
Perhaps it should, but I didn’t find anything?
Good advice, however my reasons for asking this were not “…I can always try as root …” 
rather a suspicion that my problems with opening of the device might have something to do with ownership and permissions.
So, I did run cutecom as root and device seems to have opened OK.
Firewall problem??
Doing that comes up with:
linux-zajy:/dev/serial # ls -l /dev/ttyUSB0
crw-rw---- 1 root dialout 188, 0 Jun 22 15:26 /dev/ttyUSB0
and a final edit:
Everything works fine
Device is opened and responding correctly
all it took was to run cutecom as a root
Thank you for your help and replies.
What I tried to do until now is finding out if a “normal” user may use the device. By looking at it’s permissions. Not by forcing things jumping in where it is at it deepestt and using root.
Understanding things first is better. Thus when you have such a thing which looks very much like a permission problem, the obvious questions are:
Alas it takes some time to find out due to some misunderstandings about my questions. And still instead of providing the information you are runnning loose using root. :’(. The very last thing you should do.
Nope. This is not about networking. It is about data communication ports. On a PC the same as the ol MS-DOS COM port, but then with newer (USB) hardware.
And the fact (which was not available to you when you posted) that “it works” when being root proves that it is not the firewall. Even root processes can not circumvent the firewall.
I am still not convinced that it is a good idea to use root. But that maybe due to the fact that I have no idea what the application is for.
When you think your problem is solved, that is nice for you.
I wasn’t sure if it was user/permission issue, or something else I was doing wrong.
That’s a bit dramatic?
I wasn’t doing anything apart from testing the connection…
Understanding is better indeed and I am trying to improve
Communicating via written on the interweb is not easy, especially when dealing with Dummkopf like me 
I did my best, honest
Perhaps I shouldn’t have admitted to my bad habits
Is there an alternative in this particular case?
it’s to use AT commands to modify/set bluetooh module.
If you google it up you will find kids playing with Arduino etc doing this job.
I wanted to do it with my Linux machine.
It may not be nice and proper?, but I have been able to connect to the device and do what I needed.
On Wed 22 Jun 2016 03:36:02 PM CDT, bambuko wrote:
hcvv;2783217 Wrote:
> …I am still not convinced that it is a good idea to use root…
Is there an alternative in this particular case?
hcvv;2783217 Wrote:
> …But that maybe due to the fact that I have no idea what the
> application is for…
it’s to use AT commands to modify/set bluetooh module.
If you google it up you will find kids playing with Arduino etc doing
this job.
I wanted to do it with my Linux machine.
hcvv;2783217 Wrote:
> …When you think your problem is solved, that is nice for you.
It may not be nice and proper?, but I have been able to connect to the
device and do what I needed.
Hi
Why not use the arduino IDE? Anyway, adding your user to the tty
group should have sufficed, else maybe a udev rule to temporarily give
your ‘user’ access.
–
Cheers Malcolm °¿° LFCS, SUSE Knowledge Partner (Linux Counter #276890)
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Thanks Malcolm,
I looked briefly at groups etc, but was so out of depth there, that soon abandoned this idea.
udev rule… would probably take me longer to learn, than what the actual job take;)
The reason for not using Arduino etc is that it is a one off job, which takes about 1 minute (once everything is working OK), so the plan was - no additional expenditure etc, just use what is already available to me, plus nothing permanent etc, etc.
I know you “proper” Linux people shudder at my blunderings 
… but job got done.
Being a member of the ‘dialout’ group should be all that is needed for r/w access to ttyUSB* devices.
I am sure you are right
but I come from the world where there is me and my pc
there are no administrators, superusers, alternative users, groups … etc, etc,
so I wouldn’t even know where to start with groups (or why do I need them?)
I do appreciate how difficult it must be for all you guys trying to help someone like me … lol!
thank you for trying!
In the *NIX world (everything that looks like UNIXR - Linux, Android, Apple Mac OS, BSD, IBM AIX, Sun Solaris, HP-UX, . . . ) groups are a fundamental feature of system security – even for a single user box.
Because the *NIX world splits off system functions and the associated system processes to various pseudo-users with associated Groups and Group-Access-Rights and Group-Privileges, the *NIX systems tend to be inherently robust against attacks via the network. If a user is compromised then, only that user’s data (files) can be damaged by the entity which managed to break into the system.
[HR][/HR]Bottom line: this is one of the reasons why there are not that many Anti-Virus applications on the market for *NIX systems and therefore also Linux systems.