On 18/10/11 12:00, Brian Mury wrote:
On Tue, 2011-10-18 at 11:36 -0400, Bob Goodwin wrote:
> How do I determine if I have the right serial port
> permissions, where do I look?
The serial port device should be owned by root, and belong to the
dialout group, with both the owner and the group having read and write
permissions. You can verify this like this:
> ll /dev/ttyS*
crw-rw---- 1 root dialout 4, 64 Oct 18 01:21 /dev/ttyS0
crw-rw---- 1 root dialout 4, 65 Oct 18 00:28 /dev/ttyS1
crw-rw---- 1 root dialout 4, 66 Oct 18 00:28 /dev/ttyS2
crw-rw---- 1 root dialout 4, 67 Oct 18 00:28 /dev/ttyS3
crw-rw---- 1 root dialout 4, 68 Oct 18 01:14 /dev/ttyS4
crw-rw---- 1 root dialout 4, 69 Oct 18 00:29 /dev/ttyS5
crw-rw---- 1 root dialout 4, 70 Oct 18 01:28 /dev/ttyS6
crw-rw---- 1 root dialout 4, 71 Oct 18 01:10 /dev/ttyS7
Yeah, I've got a lot of serial ports! :-)
The column that says "root" is the owner.
The column that says "dialout" is the group.
The second and third characters are the owner read/write permissions (r
or w indicates permission, - indicates no permission).
The fifth and sixth characters are the group read/write permissions.
You can run "system-config-users" as root, and add your user account to
the dialout group. You'll need to log that user out and back in after
making that change.
Brian
This is what I see there and it looks ok to me:
[bobg@box9 ~]$ ll -al /dev/ttyS*
crw-rw----. 1 root dialout 4, 64 Oct 18 03:14 /dev/ttyS0
crw-rw----. 1 root dialout 4, 65 Oct 18 03:14 /dev/ttyS1
crw-rw----. 1 root dialout 4, 66 Oct 18 03:14 /dev/ttyS2
crw-rw----. 1 root dialout 4, 67 Oct 18 03:14 /dev/ttyS3
I haven't changed anything in "system-config-users" I've set up
on a second F-15 computer and still can't see anything toggle on
DTR or RTS. Perhaps my test method is invalid? I am simply
looking at the voltage between signal ground and those two
points at the end of a cable with no termination, it is always a
high negative value, above 12 volts.
Bob