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,
>