On 3/16/06, Ralph Shumaker <[EMAIL PROTECTED]> wrote:
> Gus Wirth wrote:
>
> > Ralph Shumaker wrote:
> >
> >> Ralph Shumaker wrote:
> >>
> >>> I have just installed fc4 on a clean new system.
> >>>
> >>> On my old system, rh9 saw the modem as /dev/ttyS4 (note the "S4")
> >>> and automatically setup the link /dev/modem to point to it (or come
> >>> to think of it, I /may/ have had to set up the link manually).
> >>> Anyway, this link survived reboots.
> >>>
> >>> On my new system, fc4 sees the same modem as /dev/ttyS14 (note the
> >>> "S14") and does not set up the /dev/modem link. What's more, each
> >>> and every time I reboot, the link disappears. The link survives
> >>> logouts, but not reboots.
> >>>
> >>> It wouldn't be so bad if the PPP program interfaces would offer
> >>> /dev/ttyS14, but they don't go beyond /dev/ttyS4. But since they
> >>> offer /dev/modem, I can just link /dev/modem to /dev/ttyS14, except
> >>> that I have to do it after every boot to keep them working.
> >>>
> >>> Anyone know what's going on with the evaporating link?
> >>>
> >>>
> >> MAKEDEV(8) Linux Programmer's Manual MAKEDEV(8)
> >>
> >> NAME
> >> MAKEDEV - create devices
> >>
> >> [snip]
> >>
> >> BUGS
> >> Let's hope not. If we're lucky, any problems we'll find will be
> >> confined to the
> >> configuration files, which were written by examining the devices.txt
> >> file. If
> >> your system uses udev, conflicts between devices.txt and the
> >> in-kernel data
> >> which udev uses for naming devices may crop up.
> >>
> >> Gus suggested making a link with MAKEDEV (and reading its man) while
> >> Vinodh suggested using udev (nice pdf on that subject BTW). "man 8
> >> MAKEDEV" mentions possible conflicts between MAKEDEV and udev. Does
> >> it matter which one I use?
> >>
> >> (My thanks to Gus and Vinodh for info I didn't know.)
> >>
> >> (My thanks to Carl for reminding me of something I'd forgotten,
> >> namely "/etc/rc.local".)
> >
> >
> > After doing some more research into this, the solution I mentioned
> > won't work with Fedora Core 3 running udev because the MAKEDEV script
> > doesn't get called the normal way.
> >
> > The corrrect way to do this for systems with udev is to create a
> > little script under /etc/dev.d/$DEVNAME/ where $DEVNAME represents the
> > real device name. Here is the step-by-step method that I just tested:
> >
> > Create directory /etc/dev.d/ttyS14 like so (note that this needs to be
> > done as root or preferably use sudo):
> >
> > # mkdir /etc/dev.d/ttyS14
> >
> > Create a shell script in the new directory called modem.dev
> > Note that the .dev suffix is required. I used vi but you can use any
> > text processor of your choice. The contents of the modem.dev file are:
> >
> > <------ snip here ------->
> > #!/bin/sh
> >
> > cd /dev
> > ln -s $DEVNAME modem
> >
> > <------ snip here ------->
> >
> > The $DEVNAME environment variable is passed in by the udev system when
> > the device is created. Using this allows you to quickly change the
> > modem link by merely renaming the directory.
> >
> > Make the script executable with chmod:
> >
> > # chmod u+x /etc/dev.d/ttyS14/modem.dev
> >
> > Reboot the system. When the system starts up, udev will execute your
> > script after it creates the ttyS14 device node, thus creating a link
> > from modem to ttyS14.
> >
> > If all this seems like too much work, carl's method of putting the
> > link command in rc.local is your best solution.
>
>
> Carl's way *does* have the appeal of fewer steps. But simplicity aside,
> what are the pros and cons of one way over the other?
>
> Although I *still* don't understand why the system (fc4) erases the link
> I set up. I don't even know if it's the shutdown or the bootup that
> obliterates it.
Look at the dates in /dev. It is most likely that the whole thing
gets rebuilt from scratch at boot time. I just tried that on my FC3
system. There is nothing in /dev older than March 9,
08:38, and uptime tells me the system has been up 7 days 7:39. In the
appropriate mixed-base arithmetic, 9 08:38 + 7 7:39 = 16 16:17. The
time now is March 16, 16:23.
So I spent a few minutes fiddling with the arithmetic.
> I can't even boot up with Knoppix and check the
> directory since Knoppix does not default to being able to see into LVMs
> and I don't know how to get it to do so, not that it really matters, so
> shutdown, startup, who knows? Or maybe in rh9 I had done the rc.local
> bit. But that drive is lost.
Boot the first distribution disk of FC4 in Rescue mode. It has the
tools to deal with LVM.
carl
--
carl lowenstein marine physical lab u.c. san diego
[EMAIL PROTECTED]
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