/dev/ttyS0 permission error

Donald Arseneau asnd at triumf.ca
Sat Dec 16 07:10:01 UTC 2006


"Mikkel L. Ellertson" <mikkel at infinity-ltd.com> writes:

> Jay Cliburn wrote:
> > console for debugging kernel problems.  Whenever I start minicom on the
> > laptop, however, I'm greeted with a permission denied error to
> > /dev/ttyS0.  
> > No problem, I thought -- I'll just gin up a udev rule and set the perms
> > to 0666.  Sorry; doesn't work.  As a matter of fact, it gets worse:
> > perms on ttyS0 go to 0600 root:root as a result of my new local rule.
> > 
> > Okay, not an ideal solution, but let's modify 50-udev.rules and set the
> > default rule for tty[A-Z]* to MODE="0666".  Nope.  Now they're *all*
> > 0600 root:root.
> > 
> > Here's the rule:
> > KERNEL=="ttyS0", NAME="%k", GROUP="uucp", MODE="0666"

> configure. I was surprised to discover that FC5 didn't handle the
> serial ports. 

I haven't kept track of which versions do exactly what, but I did
see permissions on ttyS0 keep reverting on some recent versions of
RH or Fedora.   Three changes I've had to make were:



/etc/inittab:  --------------------------

# NO logins on ttyS0!
### co:12345:respawn:/sbin/agetty ttyS0 9600 vt100-nav


/etc/security/console.perms: --------------------------

# Added 
<serial>=/dev/ttyS[01]

...

# Added 
<console>  0660 <serial>     0660 root.uucp


/etc/securetty: --------------------------

# DA removed:  ttyS0



-- 
Donald Arseneau                          asnd at triumf.ca




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