MJ Ray wrote:
> Dave Cooper <dave(a)accuramatic.co.uk> wrote:
>
>> As su, chmod 777 /dev/ttyS0 fixes it, but only until it happens
>> again. ttyS0 appears to be owned by root. It seems to me maybe it
>> should be owned something/someone else to fix this permissions
>> problem but I don't have a clue who. Can anyone put me right on this
>> please?
>>
>
> Look at what group ttyS0 belongs to. Try ls -l /dev/ttyS0
> The group name will probably be just after the "root". Then, add your
> user(s) to that group with the command
> usermod -a -G whatevergroupnameitsaid username
>
>
Yes! That works! Thanks Paul, thanks MJ (hope your head's still above
water in the soggy south-west?). Just one supplementary question?
How does that
usermod -a -G whatevergroupnameitsaid username
work? Why doesn't it need to include any mention of ttyS0??
thanks, Dave
> or if that doesn't work, edit /etc/group to add the username to the
> end of the line starting with whatevergroupnameitsaid.
>
> Alternatively, change the permissions on /dev/ttyS0 forever. These
> days, that's often done by udev, so grep -r /etc/udev/rules ttyS
> to try to find where the MODE is set.
>
> Hope one of those works for you,
>