Symlink to Modem Vanishes

Symlink to Modem Vanishes

[Peter]

Hi,

Slackware 10.2 kernel 2.6.16

Why is it that the symlink /dev/modem to /dev/ttyS0 is gone when machine is 
halted and has to be made again after rebooting?

I do not know when this started, definitely it did not happen before I got my 
broadband connection a little over a year ago.

Thanks & regards
-- 
Peter

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Re: Symlink to Modem Vanishes

[chuck gelm]

Peter wrote:

>Hi,
>
>Slackware 10.2 kernel 2.6.16
>
>Why is it that the symlink /dev/modem to /dev/ttyS0 is gone when machine is 
>halted and has to be made again after rebooting?
>
>I do not know when this started, definitely it did not happen before I got my 
>broadband connection a little over a year ago.
>
>Thanks & regards
>  
>
Hi, Peter:

...because it is removed during a boot?

Edit /etc/rc.d/rc.6 and put
 ls -l /dev/modem [> /home/modem.txt]
 ls -l /dev/ttyS0     [> /home/ttyS0.txt]
immediately in front of
 'reboot' and 'halt' to see if it is still there immediately before.
It is a few lines from the bottom on my Slackware 10.2 - 2.4.31

Boot from a 'live CD' and see of the link is there to see if it is being
removed during a boot.

-or-

put "ln -s /dev/modem /dev/ttyS0" at the bottom of your /etc/rc.d/rc.local.
(did ^                                         ^ I get that right?)

HTH, Chuck


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Re: Symlink to Modem Vanishes

[Peter]

Thanks!

chuck@gelm.net said:
> Edit /etc/rc.d/rc.6 and put
>  ls -l /dev/modem [> /home/modem.txt]
>  ls -l /dev/ttyS0     [> /home/ttyS0.txt] immediately in front of
>  'reboot' and 'halt' to see if it is still there immediately before.

It does not work. When rebooting or halting it says 'read file system only' 
when it reaches those lines.

Anyhow symlink /dev/modem is removed when booting or halting.

chuck@gelm.net said:
> put "ln -s /dev/modem /dev/ttyS0" at the bottom of your /etc/rc.d/rc.local.
> (did ^      ^ I get that right?)

no, it's the other way around ln -s /dev/ttyS0 /dev/modem. Me too, I get it 
always wrong the first time around.

I had put it there alrady.

Now 

david@fierbaugh.org said: w/o copying the list

> This sounds like it may be a udev problem. Udev dynamically generates device
> nodes (/dev/###), and may be missing something. When you manually create a
> node, the next time you boot, it overwrites what you created. You have to
> setup udev to create the correct link.

> If this computer is more than a year old, it's likely that you updated from
> devfs to udev, perhaps without even knowing it (if your system does automatic
>  updates.) Most of the problems I've seen with udev are on systems that have
> been updated from devfs to udev.

> I'm not a Slack user , but there's good reading on udev at the link below,
> just ignore the Gentoo specific stuff, and perhaps look for something similar
>  for Slack. http://www.gentoo.org/doc/en/udev-guide.xml

> And on writing udev rules here: http://www.reactivated.net/writing_udev_rules.
> html

Guess he is right and the stuff he recommends is a little heavy for me. When 
booting I see that udev is started.

Regards 




-- 
Peter

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Re: Symlink to Modem Vanishes

[Peter]

After further reading in the links David suggested I did a googel 'udev 
/dev/modem'
and alas there are a lot of vanishing modems. And there was how to solve the 
problem:
Short of putting ln /dev/ttyS0 /dev/modem into rc.local.

Quote
 I finally found the recipe I needed in a ubuntu forum, using google. What I 
needed was a file named 10-local.rules placed in the /sda3/etc/udev/rules.d 
subdirectory. All the file needed was the line following:

KERNEL="ttyS1", SYMLINK="modem"

Now the modem node in the /dev directory doesn't vanish anymore.
Unquote

Will try it on next reboot
-- 
Peter

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Re: Symlink to Modem Vanishes

[Peter]

slackware 10.2 kernel 2.6.16

heisspf@skyinet.net indirectly said:
> What I  needed was a file named 10-local.rules placed in the /sda3/etc/udev/
> rules.d  subdirectory. All the file needed was the line following:

> KERNEL="ttyS0", SYMLINK="modem"

> Now the modem node in the /dev directory doesn't vanish anymore.

> Will try it on next reboot

It does not work, NAME="/dev/ttyS0" has to be added. However doing this then 
there are no /dev/ttyS*. Symlink /dev/modem points to a non existing file.

Now I found that /dev/ttyS0 is a symlink to /dev/tts/0. So I changed 
NAME="/dev/tts/0" with the effect that then there is no /dev/tts/0 but only 1, 
2 and 3.

Now I am totally confused and back to rc.local command, ln -s /dev/ttyS0 
/dev/modem.

Is there somebody to whom this males sense?

Regards
-- 
Peter

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Re: Symlink to Modem Vanishes

[Peter]

On Fri, 02 Jun 2006 14:08:22 +0800
Peter <heisspf@skyinet.net> wrote:

> slackware 10.2 kernel 2.6.16
> 
> heisspf@skyinet.net indirectly said:
> > What I  needed was a file named 10-local.rules placed in the /sda3/etc/udev/
> > rules.d  subdirectory. All the file needed was the line following:
> 
> > KERNEL="ttyS0", SYMLINK="modem"
> 
> > Now the modem node in the /dev directory doesn't vanish anymore.
> 
> > Will try it on next reboot
> 
> It does not work, NAME="/dev/ttyS0" has to be added. However doing this then 
> there are no /dev/ttyS*. Symlink /dev/modem points to a non existing file.
> 
> Now I found that /dev/ttyS0 is a symlink to /dev/tts/0. So I changed 
> NAME="/dev/tts/0" with the effect that then there is no /dev/tts/0 but only 1, 
> 2 and 3.
> 

I finally solved it, the file /etc/udev/rules.d/10-local.rules reads now:

KERNEL="ttyS0",NAME="tts/0",SYMLINK="modem"

and after reboot this morning:

ls -l /dev/modem
lrwxrwxrwx  1 root root 5 2006-06-03 15:26 /dev/modem -> tts/0

and efax, vbox for which I need the modem mostly work.

Regards

-- 
Peter
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