Ralph Shumaker wrote: [snip]
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?
Read this info about udev <http://fedora.redhat.com/docs/udev/>. udev exists because the /dev directory was getting too unwieldy. When you only have a few device files it's not too bad, but with Linux supporting more and more devices the number of entries in the /dev/ directory was getting huge. The purpose of udev is to only create a device file as needed, whereas previously all possible device files were created just in case they might be used. udev ties in tightly with the hotplug system to dynamically create device files on the fly.
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. 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.
The /dev/ directory is wiped on shutdown AND on startup. Just to make sure it's clean of extraneous entries. When the system starts up, it detects installed devices and dynamically creates the device file.
As to which method is "better", if you don't understand udev then just put your link command in rc.local and be done with it. Even if you do understand udev, it is quicker and easier for your application to use carl's method.
udev is more useful when you have a variable naming scheme for an item such as a USB thumb drive that can wind up in different locations depending on where it gets plugged in. For example, if I plug in my portable USB hard drive first, it will become /dev/sda1. But if I plug in my USB thumb drive first, it will be /dev/sda1. Now this may not matter until you start doing things like wanting to always mount the USB thumb drive on /mnt/flash no matter what the naming scheme. udev can make it so you can force the device name to be what you want for a specific device.
Gus -- [email protected] http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
