Re: hotplug script before udev
On 3/8/06, Florian Kulzer <florian@molphys.leidenuniv.nl> wrote:
> David Berg wrote:
> > On 3/8/06, Florian Kulzer <florian@molphys.leidenuniv.nl> wrote:
> >
> >>David Berg wrote:
> >>
> >>>I'm trying to automount my digital camera (mass storage) when it is
> >>>connected. I have udev scripts to give me a /dev/camera symlink which
> >>>appears to be working, and created a map in hotplug to call a script
> >>>called photodl which seems to be getting called.
> >>>
> >>>The problem is that photodl is called before the device is created from udev.
>
> [...]
>
> >>>How can I ensure that photodl is run after the device is created?
> >>
> >>I think the most reliable way is to use the PROGRAM key in your udev
> >>rule for the device. The following is an example for a PCMCIA network card:
> >>
> >>KERNEL=="eth*", SYSFS{address}=="xx:xx:xx:xx:xx:xx", NAME="wlan0", PROGRAM="/path/to/your/script"
> >>
> >>(all on the same line)
> >>
> >>/path/to/your/script should point to your script. It will be called
> >>whenever the device is created or removed. In the script you can check
> >>the $ACTION environmental variable ("add" or "remove") to know which
> >>event occurred. The manpage of udev has more details.
> >>
> >
> >
> > I was under the impression that udev's sole purpose was to name /dev
> > entries. And that hotplug is the apropriate place for calling scripts
> > that will use that device.
> >
> > I'm still foggy on how some of these systems fit together. Does it
> > matter? Looking at the hotplug scripts it would appear that scripts
> > could be called from hotplug, udev, or hal. Which is most
> > appropriate.
>
> As far as I know, udev replaces hotplug. As you point out, udev's main
> purpose is to generate the device entries in /dev as needed, but it also
> incorporates the functionality of hotplug. I had the impression that
> this was done because udev cannot really coexist with hotplug: When udev
> is installed hotplug is removed from the system, and you are asked to
> purge its configuration files. This lead me to believe that it is best
> to go "100% udev" for all device configuration and plug-in scripting.
> However, there are probably many different ways to achieve what you want
> to do. Since your hotplug script is not called at the right moment it
> seems to me that the next logical thing to try is the PROGRAM key in the
> udev rule.
>
Correct me if I'm mistaken, being that PROGRAM is a _key_ it is run
before the device is created so that it can be used to determine which
name should be used. Since it is run before the device is created, it
can't be used to mount a filesystem on that device.
dberg@chip:~$ cat /etc/udev/rules.d/10-local.rules
BUS=="usb", SYSFS{serial}=="000000009144" NAME="%k" SYMLINK="camera"
GROUP="camera" PROGRAM==/etc/hotplug/photodldberg@chip:~$ cat
/etc/hotplug/photodl
#!/bin/bash
mount /media/camera
The appropriate rule is in fstab.
When plugging in the device that matches this rule, /dev/camera is
created but the filesystem is not mounted.
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