|Using automount and samba
Automount and Samba for removable devices
Samba is great, but when it comes to removable devices, it can be a
bit problematic. Here is a solution to using samba, with automount to support
Step1. Install automount.
This requires a kernel component and a user space application. If you are
using a distribution, it may already be installed.
Step 2. Configure automount
This is documented in the automount readme, but I am not sure if it works
correctly. I suggest you start with the following settings and work from there.
zip1 -user,umask=0,fstype=vfat :/dev/sdc1
zip4 -user,umask=0,fstype=vfat :/dev/sdc4
cdrom -ro,fstype=iso9660 :/dev/scd0
In this case, there is a zip disk at /dev/sdc. For unknown
reasons, some zip disks are partitioned to use partition 1, others use partition 4.
Add both and then you can use either.
There is also a cdrom /dev/scd0
Step 3. Test you automount configuration
You will need to start/restart automount. When you change to /auto/zip1,
/auto/zip4 and /auto/cdrom, you should be able to access the media.
Step 4. Umounting.
For some reason, the --timeout 30 option did not work for me, so I added a root
* * * * * killall -USR1 automount
You can edit your crontab by typing crontab -e
It has been suggested that the correct syntax should
be --timeout=30 but RedHat 6.2's autofs package now works with a space so
I assume that most people can skip this step.
Step 5 . Samba
Now, because we want samba to give a point and click interface to the users, we
want it to show a list of available media. The way to do this is create a samba
share such as
path = /autoshare
read only = No
Step 6. Create some symbolic links
now, create the /autoshare directory and create symbolic links to the /auto/xxx
ln -s /auto/zip4 /autoshare/zip4
Step 7. Try it out
Restart samba and try it out.
You should see a share called autoshare. When you select it,
samba will stat all the files in the directory. This will trigger automount to try
and mount all the unmounted entries (which have links to them). If the device can be
mounted, the user will see it, if it can't be mounted (because there is no media), samba
will decide the file does not exist and will not list it.
The device will be umounted as soon as it can, so the user can
remove the media without having to issue eject or umount commands.
There are security risks associated with this technique, but as removable media are not
secure anyway, who cares?
Why not just use preexec and postexec?
The postexec is only executed after all handles to the share are closed, and the
connection times out. By default, the connection never times out. You can set
the timeout to one minute, but if you keep an explorer window open there are still open
handles so the timeout still won't expire.
To make matters worse, the timeout is based on a host to host session, so if you are using
another share on the machine, the timeout would never occur. That is why I worked out this
the preexec/postexec does work, but is not friendly to users who don't understand why you
can't eject a disk that is in use.
Last modified 20020507
Maintained by John Newbigin