Using a Read-Only Persistence Capability in Knoppix LiveUSBs
.
There is an intriguing comment by Klaus Knopper regarding an otherwise
little-advertised capability of Knoppix to bring in additional cloop-
compressed overlays and to combine their contents with that of the master
KNOPPIX compressed file at boot. Klaus uses this feature to add non-free
material, which CeBIT is licensed to distribute, to CeBIT versions
of KNOPPIX liveCDs, LiveDVDs and their isos. This may be found at: http://lists.debian.org/debian-knopp.../msg00005.html
AFAICT, Knoppix can handle, at present, eight overlays,
KNOPPIX0, KNOPPIX1,...KNOPPIX7. The LiveCD iso has only KNOPPIX, aka
KNOPPIX0. That leaves, for a LiveCD-sized LiveUSB, KNOPPIX1, KNOPPIX2,
...KNOPPIX7 unassigned and available.
For rather-permanent, unchanging parts of one's persistence, there are
at least three reasons one might want to utilize some of these unassigned
overlay positions, assuming one uses a LiveUSB with persistence.
1. A read-only version of the persistence material is safeguarded
against inadvertent write-over;
2 A read-only version may be compressed to 40% its ultimate size after
boot, with the same scant time penalty with which the master KNOPPIX files
are brought in; and
3. A read-only version will decrease the amount of writes associated
with its contained material over that which would occur if the material
were both read/write and uncompressed. There is a wear consideration
peculiar to USB write cycling.
Prior to Knoppix 7, I had added and/or changed a number of files and
programs beyond the standard files which come with the standard LiveCD iso.
With the advent of Knoppix 7.0, I converted these to a cloop-compressed
KNOPPIX1 and added that alongside the master KNOPPIX file in
/mnt-system/KNOPPIX/. I have developed a few additonal such additions
using Knoppix 7 since it first came out. I've recently converted these
additional changes to KNOPPIX2. I am now looking forward to further
adapting these efforts to an upcoming Knoppix 7.1. Two Screenshots, mtab
and df-h illustrate this; see Attached Images below.
I used a small bash program to facilitate and position the cloop-compressed-
read-only KNOPPIX1 and KNOPPIX2. The essential part of this program uses
Klaus K's magic formula, in essence, and for example:
One may account for the content of Knoppix changes in two groups:
1. The totality of files in /home/knoppix/ plus a small number of
individual files that may have been changed or added.
These changes may be recorded with a small bash script, like Keep*.
These changes may be restored with another small bash script, like Restore*.
2. The totality of files added via apt or Synaptic, may similarly be
expressed by another small bash script, like Uncommon.dpkg*.
*These or similar small programs, may be added to /etc/profile as follows:
Code:
Keep() { # Aid to backing-up unique user files
cd /; KEEP=/mnt-system/keep$(date +"%m%d%H").tar.gz
echo -e 'Compressing data; patience, this may take a little time..\c'
tar -cz --exclude *gvfs* --exclude *cache* \
-f $KEEP home/knoppix/ \
etc/profile etc/rc.local etc/X11/Xsession.d/45* etc/syslog-knoppix.conf \
etc/chromium/ mnt-system/boot/syslinux/syslinux.cfg
echo ".Done."; echo "Restore using the command, tar -xzf '$KEEP' -C /"
}
Restore() { # Restore $PEEK given the date, $1 in %m%d%H format
PEEK="/mnt-system/keep$1.tar.gz"
echo "Restoring '$PEEK files to /."; tar -xzf $PEEK -C /
}
Uncommon.dpkg() { # Packages uncommon to dpkg.current & "dpkg.$1"
dpkg --get-selections > /tmp/dpkg.current
comm -3 --nocheck-order /tmp/dpkg.current "dpkg.$1" | less | tee uncommon
}
I think I will use this method with the upcoming knoppix 7.1. Until now I had not really considered this possibility.
Safe and compress overlay's size sound good.
Excluding .gvfs may be a good idea; it may louse up the command.
This annoying file may or may not be hanging around to cause trouble.
I suspect it got into my distro when I added a program which uses
some gnome material. I complained to Klaus K, but he was not
sympathetic with calling it a bug. Its a feature, apparently.
An i/o re-direct command might be a more professional way of
handling the way that .gvfs trips up a command. Maybe some Bash
expert will suggest something appropriate here.
FWIW, I think .gvfs trips things up using a console command or as
part of an /etc/profile function, but as part of an executable shell
script, I don't think it gives (me) the same trouble. I can't explain
why this should be the case.
The only reason to exclude [Cc]ache files is to save the space.
I don't think they'd cause trouble unless you are a real miser on
space, like myself.
.
I get into trouble with .gvfs while in /home/knoppix.
I usually execute my bash script from a root lxterminal.
My theory is that /home/knoppix is polluted with .gvfs, while / is not.
For example, try ls -a | grep .gvfs as root in both places.
It turns out, as you say, that .gvfs is a mount point put there by some program,
possibly LibreOffice, which I use. In my case the .gvfs, as a file, never has any contents;
it does show up as in an mtab entry related to fuse.
One post I read suggests unmount and delete and see what happens.
The notion being is that if some program needs to mount something it will re-
establish the mount point. I'm trying this route at present.
FWIW, Ubuntu and others are re-routing this mount point to what we would call /run/knoppix/.gvfs,
all with no more explanation than for the earlier home directory location.
Users have been perplexed by .gvfs for as far back as 2008 I've noticed.
All my self-created mount points can be deleted when not in use. And nothing seems to be mounted on my .gvfs, still there is no way to modify it using the ordinary file system commands. So .gvfs is something else, to me seemingly introducing new system features in userspace.
Maybe no wonder Miguel de Icaza is now a dedicated Mac user...?
AFAICT, PCMan needs fuse to do something with policykit in creating LXDE,
so gvfs comes in with PCManFM. You can unmount and delete .gvfs, but it
will re-appear after a while. It is annoying, but appeals to both PCMan and
Klaus K will have been of no avail up to now.
AFAICT, PCMan needs fuse to do something with policykit in creating LXDE,
so gvfs comes in with PCManFM. You can unmount and delete .gvfs, but it
will re-appear after a while. It is annoying, but appeals to both PCMan and
Klaus K will have been of no avail up to now.
Of course, PCMan doesn't want to break Gnome, which, AFAIK is used several places in LXDE. And Klaus K wants to stay as compatible with the major desktops/APIs as possible. So they should not be expected to be positive. The trouble is with the GIO implementation, I think - KDE's version, KIO, does much of the same, but AFAIK without creating such problems.
Reply With Quote
Originally Posted by Werner P. Schulz
