Random notes from mg

Dear lazyweb, I would like to download an arbitrary ISO image (say, a Ubuntu 10.04 Desktop CD) into a directory of a USB flash drive, and then make that USB flash drive boot that ISO image. I do not want to

• re-partition or re-format the flash drive (this eliminates usb-creator, AFAIU)
• extract the contents of the ISO image into the root of the USB drive (this eliminates unetbootin)
• skip the ISO's bootloader and directly boot the kernel+initramfs from the ISO (eliminates this recipe, and this recipe)

I just want a bootloader on the USB to read the VFAT filesystem, mount the ISO image as a loop device, then chain-load the bootloader from that ISO. Bonus points for having a menu letting me choose one of several ISO images. Running a script to edit a text file (say, grub's config) to get that menu is fine.

Is this even possible? If not, can I at least have two out of three (no partition/extraction, but skipping intrinsic bootloader is fine)?

Solution that I finally chose (from Ubuntu forums):

Plug in USB key. Find out the mount point (/media/disk) and the device name (/dev/sdx) of the USB key with

$ mount|grep /media

Install GRUB 2 into the USB key with

$ sudo grub-install --root-directory=/media/usbdisk /dev/sdx

If it says something about embedding being impossible and falling back to UNRELIABLE blocklist-based setup, run

$ sudo grub-install --root-directory=/media/usbdisk /dev/sdx --force

Download a CD image, let's say ubuntu-10.10-desktop-i386.iso. Put it into /media/usbdisk/ubuntu/.

Create a text file /media/usbdisk/boot/grub/grub.cfg with

menuentry "Ubuntu 10.10 (x86 desktop livecd)" {
    set isofile="/ubuntu/ubuntu-10.10-desktop-i386.iso"
    loopback loop $isofile
    linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile quiet splash noprompt --
    initrd (loop)/casper/initrd.lz
}

You can have as many ISO images as you want, just make sure to add a menuentry for each. There's no need to run grub-install again after adding or removing a .iso file. Oh, and if you want to use an ISO file for a different distribution, you'll have to figure out the correct linux and initrd lines somehow.

Update: Ubuntu 13.04 changed the name of the kernel -- use (loop)/casper/vmlinuz.efi instead of (loop)/casper/vmlinuz.

I tested it with the following images

• ubuntu-10.04-desktop-i386.iso
• ubuntu-10.04-server-i386.iso
• ubuntu-10.04-server-amd64.iso
• ubuntu-10.10-desktop-i386.iso
• ubuntu-11.04-desktop-i386.iso
• ubuntu-11.10-desktop-i386.iso
• ubuntu-12.04-desktop-i386.iso
• ubuntu-12.04-desktop-amd64.iso
• ubuntu-12.04-server-i386.iso
• ubuntu-12.04-server-amd64.iso
• ubuntu-12.10-desktop-i386.iso
• ubuntu-12.10-desktop-amd64.iso
• ubuntu-13.04-desktop-amd64.iso

This solution skips the CD-ROM's boot menu. I haven't found a better one.

Unix is an IDE. I do my development (Python web apps mostly) with Vim with a bunch of custom plugins, shell (in GNOME Terminal: tabs rule!), GNU make, ctags, find + grep, svn/bzr/hg/git.

The current working directory is my project configuration/state. I run tests here (bin/test), I search for code here (vim -t TagName, find + grep), I run applications here (make run or bin/appname). I can multitask freely, for example, if I'm in the middle of typing an SVN commit message, I can hit Ctrl+Shift+T, get a new terminal tab in the same working directory, and look something up. No aliases/environment variables/symlinks. I can work on multiple projects at the same time. I can work remotely (over ssh).

Gary Bernhardt's screencasts on Vimeo show how productive you can get if you learn Vim and tailor it to your needs. I have Vim scripts that let me

• See the name of the class and function that I'm editing in the statusbar, even if the class/function definition is offscreen: pythonhelper.vim.
• See all pyflakes warnings and errors in a list as soon as I press F2 to save the file: python_check_syntax.vim.
• Add a "from foo.bar import Something" line at the top of the file if I press F5 when my cursor is on Something, looking up the package and module from ctags: python-imports.vim.
• Switch between production code and unit tests with a single key if the project uses one of several conventions for tests (e.g. ./foo.py <-> ./tests/test_foo.py): py-test-switcher.vim.
• Generate a command line for running one particular unit test (the one my cursor is inside) and copy it into the system clipboard, so I can run that test by Alt-Tabbing into my terminal window and pasting. py-test-runner.vim.
• Open the right file and move the cursor to the right line if I triple-click a line of traceback in a shell (or an email) then press F7 in my gvim window: py-test-locator.vim.
• Compare my version of the code with the pristine version in source control in an interactive side-by-side diff that lets me revert bits I no longer want: vcscommand.vim.
• Highlight which lines of the source are covered by my tests, if I have coverage information in trace.py format: py-coverage-highlight.vim.
• Show the signature of a function/class's __init__ when I type the name of that class/function and an open parenthesis (looked up from tags): py-function-signature.vim.
• Fold code into an outline so I only see names of methods or classes instead of their full bodies: vimrc, function PythonFoldLevel.
• Fold diff files so I can see whole hunks/files and can delete those with a single key (well, two keys -- dd). Useful for reviewing large diffs (tens of thousands of lines): vimrc, function DiffFoldLevel.

Some of these come from www.vim.org, some I've written myself, some I've taken and modified a little bit to avoid an irritating quirk or add a missing feature. Some things I don't have (and envy Emacs or IDE users for having -- like an integrated debugger for Python apps, and, generally, integration with other tools, running in the background).

It's been my plan for a long time to polish my plugins, release them somewhere (github? bitbucket? launchpad?) and upload to vim.org, but as it doesn't seem to be happening, I thought I'd at least put an svn export of my ~/.vim on the web.

I booked a stay at a particular hotel because the web page said "Free WiFi". It didn't say "all outgoing ports firewalled except for port 80 and a few other (useless) ones". Not having SSH access is most painful. Luckily, there's a solution.

You need a web server running Apache and SSH. Enable mod_proxy and mod_proxy_connect and add this to the first (i.e. default) virtual host configuration:

<VirtualHost whatever:80>
...

  # allow ssh to localhost over http proxy
  ProxyRequests on
  AllowCONNECT 22
  <Proxy localhost>
    Order allow,deny
    Allow from all
  </Proxy>

</VirtualHost>

On the client side you need proxytunnel. Sadly, it's not packaged for Ubuntu yet, but compiling from sources is trivial. Edit ~/.ssh/config and add an entry for your proxied ssh connection:

Host pmyservername
ProxyCommand proxytunnel -q -p myserver.mydomain.com:80 -d localhost:22

That's it. Now you can ssh pmyservername. (The p prefix is a reminder that I'm using a proxied connection: ssh fridge versus ssh pfridge. Also it reminds me of Terry Pratchett's Pyramids.).

For extra fun (e.g. IRC) use ssh's built-in SOCKS5 proxy: ssh -D 1080 pmyservername. Then tell the apps to use a SOCKS5 proxy on localhost. Since telling each app to use a proxy (and then, later, telling it to stop using it) is a big *pain*, and some apps (e.g. ssh) don't support proxies directly, a wrapper like tsocks is handy. Edit /etc/tsocks.conf and set the default socks server to 127.0.0.1, then use it to run apps:

$ tsocks xchat-gnome
$ tsocks bzr push lp:myprojectname

tsocks is packaged for Ubuntu.

If your hotel doesn't have free WiFi, a prepaid SIM card with 3G access could be cheaper than roaming charges. Apparently you can get one with a virtually unlimited (for a short stay, anyway) data plan for 27 EUR in Amsterdam.