[PLUG] Loss of symbolic link on re-boot

Ken Hill ken at scottshill.com
Wed Dec 26 23:40:59 UTC 2007


What is the benefit of using symbolic links?

-----Original Message-----
From: plug-bounces at lists.pdxlinux.org
[mailto:plug-bounces at lists.pdxlinux.org] On Behalf Of Richard C. Steffens
Sent: Wednesday, December 26, 2007 3:24 PM
To: General Linux/UNIX discussion and help; civil and on-topic
Subject: Re: [PLUG] Loss of symbolic link on re-boot

Rich Shepard wrote:
> On Tue, 25 Dec 2007, Richard C. Steffens wrote:
> 
>> Why would I lose a symbolic link when I re-boot the machine?
> 
>> I have a link to ttyS0 called ttyX10. ttyX10 disappears whenever I have
to
>> re-boot.
> 
>    As the two prior respondents wrote, the device goes away when you
reboot
> or unplug it. It's a result of the way udev works. Take a look at
> /etc/udev/rules.d/udev.rules (at least that's where the file's located on
my
> Slackware box).

OK. I have 17 files in /etc/udev/rules.d/. The first one is
05-udev-early.rules. The last one is 95-udev-late.rules. I assume
someone came up with some reason why the various rules should be applied
in a certain order. (From man udev I understand that's how this works.)
So, if I want to put something in that won't be changed by something
else, should I put it in 95-udev-late.rules? Or should I create a new
.rules file, something like 97-my-own-udev.rules? I'll need to study
some more to understand just how to write the rule, but at least I found
the documentation.

>    I'd set the cron jobs to reference /dev/ttyS0 (or /dev/tts/0 depending
on
> how your system is configured) and ignore the /dev/ttyX10 link.

It may be that the simplest thing to do would be to change the config
file for the X10 program and directly reference /dev/ttyS0, as you
suggest. That will mean re-installing the X10 program. A change to the
config file is only read during one of the iterations of make (I think).

Thanks, Rich, Rogan, and Eric, for the pointer to the solution.

-- 
Regards,

Dick Steffens

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