Shallow Thoughts : : install
Akkana's Musings on Open Source Computing and Technology, Science, and Nature.
Fri, 05 Feb 2016
Debian's Unstable ("Sid") distribution has been terrible lately.
They're switching to a version of X that doesn't require root,
and apparently
the X
transition has broken all sorts of things in ways that are hard to fix
and there's no ETA for when things might get any better.
And, being Debian, there's no real bug system so you can't just CC
yourself on the bug to see when new fixes might be available to try.
You just have to wait, try every few days and see if the system
That's hard when the system doesn't work at all. Last week, I was
booting into a shell but X wouldn't run, so at least I could pull
updates. This week, X starts but the keyboard and mouse don't work at all,
making it hard to run an upgrade.
has been fixed.
Fortunately, I have an install of Debian stable ("Jessie") on this
system as well. When I partition a large disk I always reserve several
root partitions so I can try out other Linux distros, and when running
the more experimental versions, like Sid, sometimes that's a life saver.
So I've been running Jessie while I wait for Sid to get fixed.
The only trick is: how can I upgrade my Sid partition while running
Jessie, since Sid isn't usable at all?
I have an entry in /etc/fstab that lets me mount my Sid
partition easily:
/dev/sda6 /sid ext4 defaults,user,noauto,exec 0 0
So I can type
mount /sid
as myself, without even needing
to be root.
But Debian's apt upgrade tools assume everything will be on /,
not on /sid. So I'll need to use chroot /sid
(as root)
to change the root of the filesystem to /sid. That only affects
the shell where I type that command; the rest of my system will still be
happily running Jessie.
Mount the special filesystems
That mostly works, but not quite, because I get a lot of errors like
permission denied: /dev/null
.
/dev/null is a device: you can write to it and the bytes disappear,
as if into a black hole except without Hawking radiation.
Since /dev is implemented by the kernel and udev, in the chroot
it's just an empty directory. And if a program opens /dev/null in
the chroot, it might create a regular file there and actually write to it.
You wouldn't want that: it eats up disk space and can slow things down a lot.
The way to fix that is before you chroot:
mount --bind /dev /sid/dev
which will make /sid/dev a mirror of the real /dev.
It has to be done before the chroot because inside the chroot,
you no longer have access to the running system's /dev.
But there is a different syntax you can use after chrooting:
mount -t proc proc proc/
mount --rbind /sys sys/
mount --rbind /dev dev/
It's a good idea to do this for /proc and /sys as well,
and Debian recommends adding /dev/pts (which must be done after you've
mounted /dev), even though most of these probably won't come into play
during your upgrade.
Mount /boot
Finally, on my multi-boot system, I have one shared /boot
partition with kernels for Jessie, Sid and any other distros I have
installed on this system. (That's
somewhat
hard to do using grub2
but easy on Debian
though you may need to
turn
off auto-update and
Debian
is making it harder to use extlinux now.)
Anyway, if you have a separate /boot partition, you'll want it mounted
in the chroot, in case the update needs to add a new kernel.
Since you presumably already have the same /boot mounted on the
running system, use mount --bind
for that as well.
So here's the final set of commands to run, as root:
mount /sid
mount --bind /proc /sid/proc
mount --bind /sys /sid/sys
mount --bind /dev /sid/dev
mount --bind /dev/pts /sid/dev/pts
mount --bind /boot /sid/boot
chroot /sid
And then you can proceed with your apt-get update
,
apt-get dist-upgrade
etc.
When you're finished, you can unmount everything with one command:
umount --recursive /sid
Some helpful background reading:
Tags: linux, debian, chroot, install, boot
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11:43 Feb 05, 2016
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Sun, 27 Dec 2015
Debian "Sid" (unstable) stopped working on my Thinkpad X201 as of the
last upgrade -- it's dropping mouse and keyboard events. With any luck
that'll get straightened out soon -- I hear I'm not the only one
having USB problems with recent Sid updates. But meanwhile,
fortunately, I keep a couple of spare root partitions so I can
try out different Linux distros. So I decided to switch to the
current Debian stable version, "Jessie".
The mouse and keyboard worked fine there. Except it turned out I had
never fully upgraded that partition to the "Jessie"; it was still on
"Wheezy". So, with much trepidation, I attempted an
apt-get update; apt-get dist-upgrade
After an interminable wait for everything to download, though, I was
faced with a blue screen asking this:
No bootloader integration code anymore.
The extlinux package does not ship bootloader integration anymore.
If you are upgrading to this version of EXTLINUX your system will not boot any longer if EXTLINUX was the only configured bootloader.
Please install GRUB.
<Ok>
No -- it's not okay! I have
good
reasons for not using grub2 -- besides which, extlinux on
exact machine has been working fine for years under Debian Sid.
If it worked on Wheezy and works on Sid, why wouldn't it work on
the version in between, Jessie?
And what does it mean not to ship "bootloader integration", anyway?
That term is completely unclear, and googling was no help.
There have been various Debian bugs filed but of course, no
explanation from the developers for exactly what does and doesn't work.
My best guess is that what Debian means by "bootloader integration"
is that there's a script that looks at /boot/extlinux/extlinux.conf,
figures out which stanza corresponds to the current system,
figures out whether there's a new kernel being installed that's
different from the one in extlinux.conf, and updates the
appropriate kernel and initrd lines to point to the new kernel.
If so, that's something I can do myself easily enough. But what if
there's more to it? What would actually happen if I upgraded the
extlinux package?
Of course, there's zero documentation on this. I found plenty of
questions from people who had hit this warning, but most were from
newbies who had no idea what extlinux was or why their systems were
using it, and they were advised to install grub. I only found one hit
from someone who was intentionally using extlinux. That person aborted
the install, held back the package so the potentially nonbooting new
version of extlinux wouldn't be installed, then updated extlinux.conf
by hand, and apparently that worked fine.
It sounded like a reasonable bet. So here's what I did (as root, of course):
- Open another terminal window and run
ps aux | grep apt
to find the apt-get dist-upgrade process and kill it.
(sudo pkill apt-get
is probably an easier approach.)
Ensure that apt has exited and there's a shell prompt in the window
where the scary blue extlinux warning was.
echo "extlinux hold" | dpkg --set-selections
apt-get dist-upgrade
and wait forever for all the
packages to install
aptitude search linux-image | grep '^i'
to find out
what kernel versions are installed. Pick one. I picked 3.14-2-686-pae
because that happened to be the same kernel I was already running,
from Sid.
ls -l /boot
and make sure that kernel is there,
along with an initrd.img of the same version.
- Edit /boot/extlinux/extlinux.conf and find the stanza
for the Jessie boot. Edit the kernel and append initrd
lines to use the right kernel version.
It worked fine. I booted into jessie with the kernel I had specified.
And hooray -- my keyboard and mouse work, so I can continue to use my
system until Sid becomes usable again.
Tags: linux, debian, extlinux
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17:28 Dec 27, 2015
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Sat, 16 Mar 2013
I'm at PyCon, and I spent a lot of the afternoon in the Raspberry Pi lab.
Raspberry Pis are big at PyCon this year -- because everybody at
the conference got a free RPi! To encourage everyone to play, they
have a lab set up, well equipped with monitors, keyboards, power
and ethernet cables, plus a collection of breadboards, wires, LEDs,
switches and sensors.
I'm primarily interested in the RPi as a robotics controller,
one powerful enough to run a camera and do some minimal image processing
(which an Arduino can't do).
And on Thursday, I attended a PyCon tutorial on the Python image processing
library SimpleCV.
It's a wrapper for OpenCV that makes it easy to access parts of images,
do basic transforms like greyscale, monochrome, blur, flip and rotate,
do edge and line detection, and even detect faces and other objects.
Sounded like just the ticket, if I could get it to work on a Raspberry Pi.
SimpleCV can be a bit tricky to install on Mac and Windows, apparently.
But the README on the SimpleCV
git repository gives an easy 2-line install for Ubuntu. It doesn't
run on Debian Squeeze (though it installs), because apparently it
depends on a recent version of pygame and Squeeze's is too old;
but Ubuntu Pangolin handled it just fine.
The question was, would it work on Raspbian Wheezy? Seemed like a
perfect project to try out in the PyCon RPi lab. Once my RPi was
set up and I'd run an apt-get update
, I used
used netsurf (the most modern of the lightweight browsers available
on the RPi) to browse to the
SimpleCV
installation instructions.
The first line,
sudo apt-get install ipython python-opencv python-scipy python-numpy python-pygame python-setuptools python-pip
was no problem. All those packages are available in the Raspbian repositories.
But the second line,
sudo pip install https://github.com/ingenuitas/SimpleCV/zipball/master
failed miserably. Seems that pip likes to put its large downloaded
files in /tmp; and on Raspbian, running off an SD card, /tmp quite
reasonably is a tmpfs, running in RAM. But that means it's quite small,
and programs that expect to be able to use it to store large files
are doomed to failure.
I tried a couple of simple Linux patches, with no success.
You can't rename /tmp to replace it with a symlink to a directory on the
SD card, because /tmp is always in use. And pip makes a new temp directory
name each time it's run, so you can't just symlink the pip location to
a place on the SD card.
I thought about rebooting after editing the tmpfs out of /etc/fstab,
but it turns out it's not set up there, and it wasn't obvious how to
disable the tmpfs. Searching later from home, the size is
set in /etc/default/tmpfs. As for disabling the tmpfs and using the
SD card instead, it's not clear. There's a block of code in
/etc/init.d/mountkernfs.sh that makes that decision; it looks like
symlinking /tmp to somewhere else might do it, or else commenting out
the code that sets RAMTMP="yes". But I haven't tested that.
Instead of rebooting, I downloaded the file to the SD card:
wget https://github.com/ingenuitas/SimpleCV/master
But it turned out it's not so easy to pip install from a local file.
After much fussing around I came up with this, which worked:
pip install http:///home/pi/master --download-cache /home/pi/tmp
That worked, and the resulting SimpleCV install worked nicely!
I typed some simple tests into the simplecv shell, playing around
with their built-in test image "lenna":
img = Image('lenna')
img.show()
img.binarize().show()
img.toGray().show()
img.edges().show()
img.invert().show()
And, for something a little harder, some face feature detection:
let's find her eyes and outline them in yellow.
img.listHaarFeatures()
img.findHaarFeatures('eye.xml').draw(color=Color.YELLOW)
SimpleCV is lots of fun! And the edge detection was quite fast on the RPi --
this may well be usable by a robot, once I get the motors going.
Tags: raspberry pi, python, programming, hardware, linux, maker
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21:43 Mar 16, 2013
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Wed, 14 Nov 2012
(This is a guest post by David North.)
Debian developers tend to get overzealous in their dependency lists, probably to avoid constant headaches from fringe cases whose favorite programs fail because they also need some obscure library or package support (and yes, I'm talking to you, Ubuntu). But what if you don't want some goofy dependency (and the cascade of other crap it pulls in?)
As a small aside, aptitude/apt-get hold <pkg> is terrific if you just want to keep a package at a pre-horkage level, but for some obcure reason you can't "hold" a package that isn't installed. So that won't work as of 11/2012.
You can however generate an equivalent package with a higher version number and install it, which naturally blocks the offending package. Even better, the replacement package need do nothing at all other than satisfy the apt database. Even better, the whole thing is incredibly simple.
First install the "equivs" package. This will deliver two programs:
- equivs-control
- equivs-build
Officially you should start with 'equivs-control <:pkgname>' which will create a file 'pkgname' in the current directory. Inside are various fields but you only need eight and can simply delete the rest. Here's approximately what you should end up with for a fictional package "pkgname":
Section: misc
Priority: optional
Standards-Version: 3.9.2
Package: pkgname
Version: 1:42
Maintainer: Your Name <your@email.address>
Architecture: all
Description: fake pkgname to block a dumb dependency
The first three lines are just boilerplate, though you may have to increment the standards-version at some point if you reuse the file. No changes are needed now.
The pkgname does actually have to match the name of the package you want to block. The version must be higher than that of the target package. Maintainer need not be you, but it's a good idea to at least use a name you recognize as yourself. Architecture can be left as "all" unless you're doing something extra tricky. Description is not necessary but a good idea; put your notes here.
The only trick is the version. Note the 1:42 structure here. The first number is the "epoch" in debian-speak, and may or may not be used. In practice I've never seen an epoch greater than one, so I suggest using either 1 or 2 here rather than just leaving it blank. You can see the epoch number in a package when you use aptitude show <pkgname>. The version is the number immediately after the colon, and for safety's sake should be considerably larger than the version you're trying to block (to avoid future updates). I like to use "42" for obvious reasons unless the actual package version is too close. Factoid: if no "epoch" is indicated debian will assume epoch 0, which will not show up as a zero in a .deb (or in aptitude show) but rather as a blank. The version number will have no colon in this event.
Having done this, all you need do is issue the command 'equivs-build path-to-pkgname' (preferably from the same directory) and you get a fake deb to install with dpkg -i. Say goodbye to the dependency.
One more trick: once you have your file <pkgname> with the Eight
Important Fields, you can pretty much skip using equivs-control. All it
does is make the initial text file, and it will be easier to edit the
one you already have with a new package name (and rename the file at
the same time). Note, however, this handy file will not necessarily be
useful on other debian-based systems or later installs, so running
equivs-control after a big upgrade or moving to another distro is very
good practice. If you compare the files and they have the same entries,
great. If not, use the new ones.
Tags: linux, debian, ubuntu, install
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11:50 Nov 14, 2012
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Sat, 08 Sep 2012
In setting up a laptop
-- Debian "Squeeze" with a Gnome 2 desktop --
for an invalid who will be doing most of her computing from bed,
we hit a snag. Two snags, actually: both related to the switching
between the trackpad and an external trackball.
Disabling and re-enabling the trackpad
First, the trackpad gets in the way when she's typing. "Disable
touchpad while typing" was already set, but it doesn't actually
work -- the mouse was always moving when her palm brushed against it.
On her desktop computer, she's always used a Logitech trackball --
never really got the hang of mice, but that trackball always worked
well for her. And fortunately, unlike a mouse, a trackball works just
fine from bed.
Once the trackball is working, there's really no need to have the
trackpad enabled. So why not just turn it off when the external trackball
is there? I thought I'd once seen a preference like that ... but
it was nowhere to be found in the Gnome 2 desktop.
It turns out the easiest way to disable a trackpad is this:
synclient TouchpadOff=1
Using 0 instead of 1 turns it back on.
So we gave her shell aliases for both these commands.
A web search will show various approaches to writing udev rules to run
something like that automatically, but she felt it was easy enough to
type a command when she switches modes, so we're going with that for now.
Emulate the middle button on an external mouse or trackball
We thought we were done -- until we tried to paste that alias into her
shell and discovered that 2-button paste doesn't work for
external mice in Squeeze.
Usually, when you have a mouse-like device that has only two buttons,
you can click the left and right buttons together to emulate a middle
click. She'd been using that on her old Ubuntu Lucid install, and it
works on pretty much every trackpad I've used.
But it didn't work with the USB trackball on Squeeze.
Gnome used to have a preference for middle button emulation,
but it's gone now.
There's a program you can install called
gpointing-device-settings that offers a 2-button emulation setting
... but it doesn't save the settings anywhere.
And since it's a GUI program you can't make it part of your login or
boot process -- you'd have to go through and click to set it every time.
Not happening.
2-buttom emulation is an X setting -- one of the settings that used to be
specified in Xorg.conf, and now wanders around to different places
on every distro. A little web searching didn't turn up a likely
candidate for Squeeze, but it did turn up a way that's probably
more distro independent: the xinput command.
After installing xinput, you need the X ID of the external mouse or trackball.
xinput list
should show you something like this (plus more stuff for keyboards
and possibly other devices):
$ xinput list
Virtual core pointer id=2 [master pointer (3)]
Virtual core XTEST pointer id=4 [slave pointer (2)]
SynPS/2 Synaptics TouchPad id=10 [slave pointer (2)]
Kensington Kensington USB/PS2 Orbit id=13 [slave pointer (2)]
Once you have the id of the external device, list its properties:
$ xinput list-props 13 ~ 9:01PM
Device 'Kensington Kensington USB/PS2 Orbit':
Device Enabled (132): 1
... long list of other properties ...
Evdev Middle Button Emulation (303): 0
Evdev Middle Button Timeout (304): 50
... more properties ...
You can see that middle button emulation is disabled (0).
So turn it on:
$ xinput --set-prop 13 "Evdev Middle Button Emulation" 1
Click both buttons together, and sure enough -- a middle button paste!
I added that to the alias that turns the trackpad off -- though of course,
it could also be added to a udev rule that fires automatically
when the mouse is plugged in.
Tags: linux, laptop
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15:34 Sep 08, 2012
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Thu, 24 Nov 2011
A few days ago, I wrote about
how to
set up and configure extlinux (syslinux) as a bootloader.
But on Debian or Ubuntu,
if you make changes to files like /boot/extlinux/extlinux.conf
directly, they'll be overwritten.
The configuration files are regenerated by a program
called extlinux-update, which runs automatically every time you
update your kernel. (Specifically, it runs from the postinst script of
the linux-base package:
you can see it in /var/lib/dpkg/info/linux-base.postinst.)
So what's a Debian user to do if she wants to customize the menus,
add a splash image or boot other operating systems?
First, if you decide you really don't want Debian overwriting your
configuration files, you can change disable updates
by editing /etc/default/extlinux.
Just be aware you won't get your boot menu updated when you install new
kernels -- you'll have to remember to update them by hand.
It might be worth it: the automatic update is nearly as annoying as
the grub2 updater: it creates two automatic entries for every kernel
you have installed. So if you have several distros installed, each
with a kernel or two in your shared /boot,
you'll get an entry to boot Debian Squeeze with the
Ubuntu Oneiric kernel, one for Squeeze with the Natty kernel,
one for Squeeze with the Fedora 16 kernel ... as well as entries
for every kernel you have that's actually owned by Debian.
And then for each of these, you'll also get a second entry,
to boot in recovery mode. If you have several distros installed,
it makes for a very long and confusing boot menu!
It's a shame that the auto-updater doesn't restrict itself to kernels
managed by the packaging system, which would be easy enough to do.
(Wonder if they would accept a patch?)
You might be able to fudge something that works right by setting up
symlinks so that the only readable kernels actually live on the root
partition, so Debian can't read the kernels from the other
distros. Sounds a bit complicated and I haven't tried it.
For now, I've turned off automatic updating on my system.
But if your setup is simpler --
perhaps just one Debian or one Ubuntu partition plus some non-Linux
entries such as BSD or Windows -- here's how to set up Debian-style
automatic updating and still keep all your non-Linux boot entries
and your nice menu customizations.
Debian automatic updates and themes
First, take a quick look at /etc/default/extlinux and customize
anything there you might need, like the names of the kernels, kernel
boot parameters or timeout.
See man extlinux-update
for details.
For configuring menu colors, image backgrounds and such, you'll need to
make a theme. You can see a sample theme by installing the package
syslinux-themes-debian -- but watch out.
If you haven't configured apt not to pull in suggested packages, that
may bring back grub or grub-legacy, which you probably don't want.
You can make a theme without needing that package, though.
Create a directory /usr/share/syslinux/themes/mythemename
(the extlinux-update man page claims you can put a theme anywhere and
specify it by its full path, but it lies). Create a directory called
extlinux inside it, and make a file with everything you want
from extlinux.conf. For example:
default 0
prompt 1
timeout 50
ui vesamenu.c32
menu title Welcome to my Linux machine!
menu background mysplash.png
menu color title 1;36 #ffff8888 #00000000 std
menu color unsel 0 #ffffffff #00000000 none
menu color sel 7 #ff000000 #ffffff00 none
include linux.cfg
menu separator
include themes/mythemename/other.cfg
Note that last line: you can include other files from your theme.
For instance, you can create a file called other.cfg
with entries for other partitions you want to boot:
label oneiric
menu label Ubuntu Oneiric Ocelot
kernel /vmlinuz-3.0.0-12-generic
append initrd=/initrd.img-3.0.0-12-generic root=UUID=c332b3e2-5c38-4c50-982a-680af82c00ab ro quiet
label fedora
menu label Fedora 16
kernel /vmlinuz-3.1.0-7.fc16.i686
append initrd=/initramfs-3.1.0-7.fc16.i686.img root=UUID=47f6b1fa-eb5d-4254-9fe0-79c8b106f0d9 ro quiet
menu separator
LABEL Windows
KERNEL chain.c32
APPEND hd0 1
Of course, you could have a debian.cfg, an ubuntu.cfg,
a fedora.cfg etc. if you wanted to have multiple distros
all keeping their kernels up-to-date. Or you can keep the whole
thing in one file, theme.cfg. You can make a theme as complex
or as simple as you like.
Tags: linux, boot, extlinux, syslinux, debian, ubuntu
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12:26 Nov 24, 2011
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Sun, 20 Nov 2011
When my new netbook arrived, I chose Debian Squeeze as the first Linux
distro to install, because I was under the impression it still used grub1,
and I wanted to
avoid grub2.
I was wrong -- Squeeze uses grub2. Uninstalling grub2, installing grub-legacy
and running grub-install and update-grub didn't help; it turns out
even in Debian's grub-legacy package, those programs come from
grub2's grub-common package.
What a hassle! But maybe it was a blessing in disguise -- I'd been
looking for an excuse to explore extlinux as a bootloader as a way
out of the grub mess.
Extlinux is one of the many spinoffs of syslinux -- the bootloader
used for live CDs and many other applications. It's not as commonly used as
a bootloader for desktops and laptops, but it's perfectly capable of that.
It's simple, well tested and has been around for years. And it supports
the few things I want out of a bootloader: it has a simple
configuration file that lives on the /boot partition;
it can chain-load Windows, on machines with a Windows partition;
it even offers pretty graphical menus with image backgrounds.
Since there isn't much written about how to use extlinux, I wrote up
my experiences along with some tips for configuring it. It came out
too long for a blog article, so instead I've made it its own page:
How to install
extlinux (syslinux) as a bootloader.
Tags: linux, boot, extlinux, syslinux
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16:19 Nov 20, 2011
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Fri, 28 Oct 2011
I wrote a few days ago about my
multi-distro
Linux live USB stick. Very handy!
But one thing that bugs me about live distros:
they're set up with default settings and don't
have a lot of the programs I want to use. Even getting a terminal
takes quite a lot of clicks on most distros. If only they would save
their settings!
It's possible to make a live USB stick "persistent", but not much is
written about it. Most of what's written tells you to create the USB
stick with usb-creator -- a GUI app that I've tried periodically for
the past two years without ever once succeeding in creating a bootable
USB stick.
Even if usb-creator did work, it wouldn't work with a multi-boot
stick like this one, because it would want to overwrite the whole drive.
So how does persistence really work? What is usb-creator doing, anyway?
How persistence works: Casper
The best howto I've found on Ubuntu persistence is
LiveCD
Persistence. But it's long and you have to wade through a lot of
fdisk commands and similar arcana. So here's how to take your
multi-distro stick and make at least one of the installs persistent.
Ubuntu persistence uses a package called casper which overlays
the live filesystem with the contents of another filesystem.
Figuring out where it looks for that filesystem is the key.
Casper looks for its persistent storage in two possible places: a
partition with the label "casper-rw", and a file named
"casper-rw" at the root of its mounted partitions.
So you could make a separate partition labeled "casper-rw", using your
favorite partitioning tool, such as gparted or fdisk. But if you already
have your multi-distro stick set up as one big partition, it's just as
easy to create a file. You'll have to decide how big to make the file,
based on the size of your USB stick.
I'm using a 4G stick, and I chose 512M for my persistent partition:
$ dd if=/dev/zero of=/path/to/casper-rw bs=1M count=512
Be patient: this step takes a while.
Next, create a filesystem inside that file. I'm not sure what the
tradeoffs are among various filesystem types -- no filesystem is
optimized for being run as a loopback file read from a vfat USB stick
that was also the boot device. So I flipped a coin and used ext3:
$ mkfs.ext3 /path/to/casper-rw
/path/to/casper-rw is not a block special device.
Proceed anyway? (y,n) y
One more step: you need to add the persistent flag to your boot
options. If you're following the multi-distro USB stick tutorial I
linked to earlier, that means you should edit boot/grub/grub.cfg on
the USB stick, find the boot stanza you're using for Ubuntu, and make
the line starting with linux look something like this:
linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile quiet splash noprompt persistent --
Now write the stick, unmount it, and try booting your live install.
Testing: did it work?
The LiveCD/Persistence page says persistent settings aren't
necessarily saved for the default "ubuntu" user, so it's a good idea
to make a new user. I did so.
Oops -- about that Ubuntu new user thing
But at least in Ubuntu Oneiric: there's a problem with that. If you
create a user, even as class Administrator (and of course you do want
to be an Administrator), it doesn't ask you for a password. If you
now log out or reboot, your new user should be saved -- but you won't
be able to do anything with the system, because anything that requires
sudo will prompt you for your nonexistent password. Even attempting to
set a password will prompt you for the nonexistent password.
Apparently you can "unlock" the user at the time you create it, and
then maybe it'll let you set a password. I didn't know this beforehand,
so here's how to set a password on a locked user from a terminal:
$ sudo passwd username
For some reason, sudo will let you do this without prompting for a
password, even though you can't do anything administrative through the GUI.
Testing redux
Once you're logged in as your new user, try making some changes.
Add and remove some items from the unity taskbar. Install a couple
of packages. Change the background.
Now try rebooting. If your casper-rw file worked, it should remember your
changes.
When you're not booted from your live USB stick, you can poke around
in the filesystem it uses by mounting it in "loopback" mode.
Plug the stick into a running Linux machine, mount it the usb stick,
then mount it with
$ sudo mount -o loop /path/to/casper-rw /mnt
/path/to is wherever you mounted your usb stick -- e.g. /media/whatever.
With the file mounted in loopback mode,
you should be able to adjust settings or add new files without
needing to boot the live install -- and they should show up the
next time you use the live install.
My live Ubuntu Oneiric install is so much more fun to use now!
Tags: ubuntu, linux, install, grub
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15:41 Oct 28, 2011
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