Default ttyS1 permission setting

gilester · 03-03-2005, 02:21 PM

Hi. I'm using Mandrake 10.0. I have a script that needs to talk to /dev/ttyS1. The default permission of ttyS1 seems to be 660.

I can 'su' then 'chmod 666 /dev/ttyS1'. This is fine, but when the machine reboots (or, it seems, I log on the the graphical session), the permission is re-set to 660 - and my script fails to access the port.

Does anyone know what setting I need to change to have the default permission of ttyS1 as user-read/writable?

Thanks. Giles.

slakmagik · 03-03-2005, 09:35 PM

Not all that familiar with Mandrake but I assume it uses udev so there's nothing fixed about dev. You could try modifying your udev perms. Better, maybe adding yourself to the tty group (or whatever group owns the device) would work.

bunnadik · 03-04-2005, 01:29 AM

@digiot: Well, MDK10.1 uses udev, 10.0 uses devfs.

@gilester: Normally devices like some tty's, disks, audio and floppy are owned by the logged in user. This is done
by "session optional pam_console.so" in /etc/pam.d/login or /etc/pam.d/*dm. Make sure you have that entry.
That should also touch a file named as your login in /var/run/console/.

- Peder

gilester · 03-07-2005, 04:13 AM

Peder,

Thanks for the reply. I do have the line "session optional pam_console.so" in /etc/pam.d/login, however I do not have anything in /var/run/console. I'm afraid I didn't quite understand what you meant with the touch part. Do I just type "touch /var/run/console/<username>"?

Thanks, Giles.

opjose · 03-07-2005, 05:30 AM

The file

/etc/udev/permissions.d/00-udev.permissions

sets up the default TTY permissions at boot.

Just change it as needed.

bunnadik · 03-07-2005, 11:10 AM

@opjose: there is no udev in 10.0 and I don't think it's the right solution even for 10.1

/etc/pam.d/login only runs if you boot in console mode and login (and use startx to start X)
If you boot into X check /etc/pam.d/xdm (or gdm or kdm).

The touching part is done by the console module. You can't do it yourself, it's just an indication
that everything works.

- Peder

opjose · 03-07-2005, 11:44 AM

My bad on 10.0.

But it does apply for 10.1 as I'm looking at two 10.1 systems with it right now.

It does set the TTY perms as the file itself contains the mode permissions for the ttys.

bunnadik · 03-07-2005, 11:57 AM

Quote:

It does set the TTY perms

Hmm, my file has "ttyS*:root:uucp:0660" but when I 'ls -la /dev/ttyS1' it's "crw-rw---- 1 peder uucp 4, 65 feb 6 21:08 /dev/ttyS1"
AFAI can see something changed it from root to peder and I know from experimenting with ldap that if you miss
the console.so in pam.d you can't acces a lot of /dev entries you normally can.

- Peder

opjose · 03-07-2005, 01:43 PM

Yes good point.

Now you are going to force me to step through the boot.