Hello,
I'd like to ask for your comments about handling of external usb devices on grml.
As you might know mounting usb pens on grml is possible via running 'mount /mnt/external1' (corresponding to /dev/sda1) and 'mount /mnt/external' (corresponding to /dev/sda).
As stated in a mail by Tong to the grml user mailinglist the problems start with multiple devices or devices with several partitions on it. I'd like to improve usability and handling of it therefore.
Thanks for input goes to Tong and Alexander Steinboeck, please read on for details about my solution.
################################################################################ /mnt/external[1] will be left without any changes, we will stay completely backwards compatible. Additionally we will create /dev/usb-sd* devices via udev rules like:
# cat /etc/udev/usbpen.rules SUBSYSTEM=="block", BUS=="usb", KERNEL=="sd[a-z]*", ACTION=="add", SYMLINK+="usb-%k", GROUP="users", NAME="%k" SUBSYSTEM=="block", BUS=="usb", KERNEL=="sd[a-z]*", ACTION=="add", RUN+="/bin/mkdir -p /mnt/usb-%k" SUBSYSTEM=="block", BUS=="usb", KERNEL=="sd[a-z]*", ACTION=="add", RUN+="/bin/sleep 2" SUBSYSTEM=="block", BUS=="usb", KERNEL=="sd[a-z]*", ACTION=="add", RUN+="/usr/sbin/create_mnt_labels" SUBSYSTEM=="block", BUS=="usb", KERNEL=="sd[a-z]*", ACTION=="add", RUN+="/usr/sbin/rebuildfstab -r -u 1000 -g 1000" ACTION=="remove", KERNEL=="sd[a-z]*", RUN+="/usr/sbin/rebuildfstab -r -u 1000 -g 1000" ACTION=="remove", KERNEL=="sd[a-z]*", RUN+="/bin/rmdir /mnt/usb-%k", OPTIONS="last_rule"
So we have the following devices available when plugging in an usb pen with 4 partitions on it:
# ls -la /dev/usb* /dev/external* /dev/sd* lrwxrwxrwx 1 root root 3 2006-09-03 17:25 /dev/external -> sda lrwxrwxrwx 1 root root 4 2006-09-03 17:25 /dev/external1 -> sda1 lrwxrwxrwx 1 root root 4 2006-09-03 17:25 /dev/external2 -> sda2 lrwxrwxrwx 1 root root 4 2006-09-03 17:25 /dev/external3 -> sda3 lrwxrwxrwx 1 root root 4 2006-09-03 17:25 /dev/external4 -> sda4 brw-rw---- 1 root users 8, 0 2006-09-03 17:25 /dev/sda brw-rw---- 1 root users 8, 1 2006-09-03 17:25 /dev/sda1 brw-rw---- 1 root users 8, 2 2006-09-03 17:25 /dev/sda2 brw-rw---- 1 root users 8, 3 2006-09-03 17:25 /dev/sda3 brw-rw---- 1 root users 8, 4 2006-09-03 17:25 /dev/sda4 lrwxrwxrwx 1 root root 3 2006-09-03 17:25 /dev/usb-sda -> sda lrwxrwxrwx 1 root root 4 2006-09-03 17:25 /dev/usb-sda1 -> sda1 lrwxrwxrwx 1 root root 4 2006-09-03 17:25 /dev/usb-sda2 -> sda2 lrwxrwxrwx 1 root root 4 2006-09-03 17:25 /dev/usb-sda3 -> sda3 lrwxrwxrwx 1 root root 4 2006-09-03 17:25 /dev/usb-sda4 -> sda4
According to that we will have the following directories available in /mnt:
# ls -lad /mnt/[eu]* drwxr-xr-x 2 root root 4096 2006-03-08 19:55 /mnt/external/ drwxr-xr-x 2 root root 4096 2006-03-08 19:55 /mnt/external1/ drwxr-xr-x 2 root root 4096 2006-09-03 17:25 /mnt/usb-sda/ drwxr-xr-x 2 root root 4096 2006-09-03 17:25 /mnt/usb-sda1/ drwxr-xr-x 2 root root 4096 2006-09-03 17:25 /mnt/usb-sda2/ drwxr-xr-x 2 root root 4096 2006-09-03 17:25 /mnt/usb-sda3/ drwxr-xr-x 2 root root 4096 2006-09-03 17:25 /mnt/usb-sda4/
As /dev/sda4 contains a labeled filesystem the script /usr/sbin/create_mnt_labels will create a new directory in /mnt:
# vol_id /dev/sda4 ID_FS_USAGE=filesystem ID_FS_TYPE=xfs ID_FS_VERSION= ID_FS_UUID=dc79eb17-9f98-49c7-9cfc-10d8fd279215 ID_FS_LABEL=foobar ID_FS_LABEL_SAFE=foobar # ls -la /mnt/foobar total 8 drwxr-xr-x 2 root root 4096 2006-09-03 18:05 ./ drwxr-xr-x 24 root root 4096 2006-09-03 18:05 ../
So mounting via label is possible therefore too with root-permissions:
# mount -L foobar /mnt/foobar
/etc/fstab will be updated as well (see the udev rule above, 2 seconds delay so we really catch all devices) and therefore will look like:
# cat /etc/fstab [...] # Added by GRML /dev/hda1 /mnt/hda1 ntfs noauto,nouser,dev,suid,exec,ro,umask=000,uid=1000,gid=1000 0 0 # Added by GRML /dev/sda1 /mnt/sda1 vfat noauto,nouser,dev,suid,exec,umask=000,uid=1000,gid=1000 0 0 # Added by GRML /dev/sda2 /mnt/sda2 vfat noauto,nouser,dev,suid,exec,umask=000,uid=1000,gid=1000 0 0 # Added by GRML /dev/sda3 /mnt/sda3 vfat noauto,nouser,dev,suid,exec,umask=000,uid=1000,gid=1000 0 0 # Added by GRML /dev/sda4 /mnt/sda4 vfat noauto,nouser,dev,suid,exec,umask=000,uid=1000,gid=1000 0 0 # Added by GRML /dev/usb-sda /mnt/usb-sda auto users,noauto,nodev,noatime,nosuid,noexec,rw,uid=1000,gid=1000 0 0 # Added by GRML /dev/usb-sda1 /mnt/usb-sda1 auto users,noauto,nodev,noatime,nosuid,noexec,rw,uid=1000,gid=1000 0 0 # Added by GRML /dev/usb-sda2 /mnt/usb-sda2 auto users,noauto,nodev,noatime,nosuid,noexec,rw,uid=1000,gid=1000 0 0 # Added by GRML /dev/usb-sda3 /mnt/usb-sda3 auto users,noauto,nodev,noatime,nosuid,noexec,rw,uid=1000,gid=1000 0 0 # Added by GRML /dev/usb-sda4 /mnt/usb-sda4 auto users,noauto,nodev,noatime,nosuid,noexec,rw,uid=1000,gid=1000 0 0
So you have the old /dev/sd* entries as usual and additionally the new, but more restricted ones meant for use as normal user. Mounting as user with uid 1000 (= user grml on the live-cd) is possible via running for example "mount /mnt/usb-sda2".
As soon as you unplug the usb device /etc/fstab will be updated again so all invalid/not-anymore-existing entries will be removed automatically. The /mnt/usb-sd* directories will be deleted as well. The fs-label directories in /mnt won't be deleted automatically.
If you want to disable the above feature at all on your grml system you would just have to remove the according udev rules file. This will be documented of course. ################################################################################
Please let me know what you think about it. If you're happy with this solutions I'd implement it so you can test it in real-live with the upcoming grml 0.7-1 devel-release.
regards, -mika-