Shallow Thoughts : : Apr

Akkana's Musings on Open Source Computing and Technology, Science, and Nature.

Tue, 29 Apr 2008

How often does updatedb really need to run?

Since updating to Hardy, I've been getting mail from Anacron:
slocate: fatal error: load_file: Could not open file: /etc/updatedb.conf: No such file or directory

That's the script that updates the database for locate, Linux's fast find system. I figured I must have screwed something up when I moved that slocate cron script from cron.daily to cron.weekly (because I hate having my machine slow to a crawl as soon as I boot it in the morning, and it doesn't bother me if the database doesn't necessarily have files added in the last day or two).

But after talking to some other folks and googling for Ubuntu bugs, I discovered I wasn't the only one getting that mail, and there was already a bug covering it. Comparing my setup with another Hardy user's, I found that the file slocate was failing to find, /etc/updatedb.conf, belongs to a different package, mlocate. If mlocate is installed, then slocate's cron script works; otherwise, it doesn't. Sounds like slocate should have a dependency that pulls in mlocate, no?

But wait, what do these two packages do? Let's try a little aptitude search locate:

p   dlocate                         - fast alternative to dpkg -L and dpkg -S   
p   kio-locate                      - kio-slave for the locate command          
i   locate                          - maintain and query an index of a directory
p   mlocate                         - quickly find files on the filesystem based
i   slocate                         - Secure replacement of findutil's locate   
Okay, forget the first two, but we have locate, mlocate, and slocate. How do they relate?

Worse, if I install mlocate (so slocate will work) and then look in my cron directories, it turns out I now have, count 'em, five different cron scripts that run updatedb. They are:

In cron.daily:

locate: 72 lines! but a lot of that is comments and pruning, and a lot of fiddling to figure out what version of the kernel is running to see whether it can pass any advanced flags when it tries to renice the process. In the end it calls updatedb.findutils (note no full path, though it uses a full path when it checks for it earlier in the script).

slocate: A much simpler but unfortunately buggy 20 lines. It checks for /etc/updatedb.conf, runs it if it exists, fiddles with ionice, checks again for /etc/updatedb.conf, and based on whether it finds it, runs either /usr/bin/slocate -u or /usr/bin/slocate -u -f proc. The latter path is what was failing and sending root mail every time the script was run.

mlocate: an even slimmer 12 line script, which checks for /usr/bin/updatedb.mlocate and, if it exists, fiddles ionice then runs /usr/bin/updatedb.mlocate.

In cron.weekly:

Two virtually identical scripts called find.notslocate and find.notslocate.dpkg-new, which differ only in dpkg-new having more elaborate ionice options. They both run updatedb. And which updatedb would that be? Probably /usr/bin/updatedb, which links to /etc/alternatives/updatedb, which probably links to either updatedb.mlocate or updatedb.slocate, whichever you've installed most recently. But in either case, it's hard to see why you'd need this script running weekly if you're already running both flavors of updatedb from other scripts cron.daily. And having two copies of the script is just plain wrong (and there was already a bug filed on it). (As long as you're poking around in cron.daily and cron.weekly, check and see if you have any more of these extra dpkg-new or dpkg-old scripts -- they might be slowing down your machine for no reason.)

Further research reveals that mlocate is a new(ish) package intended to replace slocate. (There was a long discussion of that on ubuntu-devel, leading to the replacement of slocate with mlocate very late in the Hardy development cycle. There was also lots of discussion of "tracker", apparently a GUI fast find tool that can only search in the user's home directory.)

What is this mlocate? The m stands for "merge": the advantage of mlocate is that it can merge new results into its existing database instead of replacing the whole thing every time. Sounds good, right? However, the down side is that mlocate apparently can't to purge its database of old files that no longer exist, and these files will clutter up your locate results. Running locate -e will keep them from being printed -- but there seems to be no way to set this permanently, via an environment variable or .locaterc file, nor to tell updatedb.mlocate to clean up its database. So you'll need to alias locate to locate -e if you want sensible behavior. Or go back to slocate. Sigh.

Cleaning up

The important thing is to get rid of most of those spurious updatedb cron scripts. You might choose to run updatedb daily, weekly, or only when you choose to run it; but you probably don't want five different scripts running two different versions of updatedb at different times. The packages obviously aren't cleaning up after themselves, so let's do a little manual cleanup.

That find.slocate script looks suspicious. In fact, if you run dpkg -S find.notslocate, you find out that it doesn't belong to any package -- not only should the .dpkg-old version not be there, neither should the other one! So out they go.

As for slocate and mlocate, it's important to know that the two packages can coexist: installing mlocate doesn't remove slocate or vice versa. A clean Hardy install should have only mlocate; upgrades from Gutsy are more likely to have a broken slocate.

Having both packages probably isn't what you want. So pick one, and remove or disable the other. If mlocate is what you want, apt-get purge slocate and just make sure that /etc/cron.*/slocate disappears. If you decide you want slocate, it's a little trickier since the slocate package is broken; but you can fix it by creating an empty /etc/updatedb.conf so updatedb.slocate won't fail.

Tags: , , ,
[ 21:48 Apr 29, 2008    More linux/install | permalink to this entry | comments ]

Sat, 26 Apr 2008

Republicans fight to preserve gender pay gap

Dahlia Lithwick wrote a terrific article in yesterday's Slate about the shameful behavior of the Republicans in the Senate in blocking a bill that would have allowed women to sue for pay discrimination.

The Lilly Ledbetter Fair Pay Act was written in response to the case brought by Lilly Ledbetter against the Goodyear Tire and Rubber Company. Courts had found that she was definitely the subject of discrimination: her pay was as much as 40% less than men doing a similar job (despite her excellent reviews), one year she was actually paid below Goodyear's own minimum threshold for that position, she had been explicitly barred from discussing salary with her coworkers (this is apparently legal, at least in Alabama), and she had been told explicitly by a manager at Goodyear that that the "plant did not need women, that [women] didn't help it, [and] caused problems."

No one at any level has disputed that Ms. Ledbetter was discriminated against -- even the Supreme Court. However, the Supremes threw out her appeal last year on the basis that the statute of limitations had run out and she should have filed her case within 180 days of receiving her first paycheck. In other words, as long as you don't know when you're hired that your pay is discriminatory, it doesn't matter if you find out later; it'll be too late then, so forget it. Pay discrimination is fine, and not actionable, as long as you can delay the victim's finding out about it for a few months.

Senate Republicans believe so strongly in a company's right to discriminate that they not only argued against the bill, they actually filibustered against it!

For more gory details of the case, read Lithwick's excellent Slate article. But even if you don't, be aware if you're considering voting for John McCain in November that although he was campaigning instead of voting on this bill, he proclaimed agreement with the rest of his party in opposing the Fair Pay Act.

So if you're against pay discrimination ... or if you're a woman and might be the victim of such discrimination ... be aware that John McCain is not on your side.

Tags: , ,
[ 20:26 Apr 26, 2008    More politics | permalink to this entry | comments ]

Tue, 22 Apr 2008

Autologin changes again for Hardy's upstart

Seems like each new Ubuntu release makes a few gratuitous changes to the syntax of system files. Today's change involves autologin, controlled by the "upstart" system (here's what I wrote about the previous syntax for autologin under upstart).

The /usr/bin/loginscript still hasn't changed, and this still works:

#! /bin/sh
/bin/login -f yourusername

But the syntax has changed a little for the getty line in /etc/event.d/tty1: respawn is now on its own line (I don't know if that matters -- I still can't find any documentation on this file's syntax, though I found a new upstart page that links to some blog entries illustrating how upstart can be used to start system daemons like dbus). And the getty now needs an exec before it. Like this:

exec /sbin/getty -n -l /usr/bin/loginscript 38400 tty1

Update: this changed again in Karmic Koala: the file has moved from /etc/event.d/tty1 to /etc/init/tty1.conf.

Tags: , ,
[ 15:27 Apr 22, 2008    More linux | permalink to this entry | comments ]

Sun, 20 Apr 2008

Upgrading from Ubuntu Gutsy to Hardy

I finally had a moment to upgrade my desktop to Ubuntu's "Hardy Heron". I followed the same procedure as when I went from feisty to gutsy:
  1. cp -ax / /hardy
  2. cp -ax /dev/.static/dev/* /hardy/dev/
  3. Fix up files like /hardy/etc/fstab and /boot/grub/menu.lst
  4. Reboot into the newly copied gutsy
  5. do-release-upgrade -d

It took an hour or two to pull down all the files, followed by a long interval of occasionally typing Y or N, and then I was ready to start cleaning up some of the packages I'd noticed flying by that I didn't want. Oops! I couldn't remove or install anything with apt-get, because: dpkg --configure -a
But I couldn't dpkg --configure -a because several packages were broken.

The first broken package was plucker, which apparently had failed to install any files. Its postinstall script was failing because it had no files to operate on; and then I couldn't do anything further with it because apt-get wouldn't do anything until I did a dpkg --reconfigure -a

I finally got out of that by dpkg -P plucker; then after several more dpkg --reconfigure -a rounds I was eventually able to apt-get install plucker (which installed just fine the second time).

But apt still wasn't happy, because it wanted to run the trigger for initramfs-tools, which wouldn't run because it wanted kernel modules for some specific kernel version in /lib/modules. I didn't have any kernel modules because I'm not running Ubuntu's kernel (I'm stuck on 2.6.23 because bug 10118 makes all 2.6.24 variants unable to sync with USB Palm devices). But I couldn't remove initramfs-tools because udev (along with a bunch of other less important packages) depends on it. I finally found my way out of that by removing /var/lib/dpkg/triggers/initramfs-tools. I reported it as bug 220094.

Update: I forgot to mention one important thing I hit both on this machine and earlier, on the laptop: /usr/bin/play (provided by the "sox" package) no longer works because it now depends on a zillion separate libraries. apt-get install libsox-fmt-all to get all of them.

Tags: , , ,
[ 21:02 Apr 20, 2008    More linux/install | permalink to this entry | comments ]

Sat, 12 Apr 2008

GIMP for middle school kids

I've been helping out with an extracurricular GIMP class that a local Linux and free software advocate, Christian Einfeldt, has organized at a middle school in San Francisco.

The class meets on a Saturday once or twice a month, so there's plenty of time to forget things between sessions, and most of the kids don't have a lot of prior computer experience (I'm told many of them are behavior problems or otherwise "at risk", but I sure wouldn't have guessed that from their exemplary behavior in class.) Despite the obstacles, the kids have learned some impressive image editing skills in a very short time! Lots of them have figured out how to set their Edubuntu desktop background; I've seen abstract patterns, photographs decorated in various ways (today one girl was painting a mouth, hair and jewelry on a photograph of a chimpanzee's face, and it came out looking very funny), photos of the students themselves pasted into exotic locales, and so on.

It's also an interesting exercise for me in seeing what beginning users find difficult to understand and what aspects of GIMP's user interface are difficult to explain. An additional challenge is that this classroom has no projector or centrally visible screen. So you can't just demonstrate how something works; everything must be explained slowly in words while the students follow along with each step, and then we have to go through the room helping students as they try to remember the steps.

One of the first tasks they take on is combining images: start with a photo of themselves, or of an animal or car, select it and paste it into another image. What's the easiest way of explaining selection of arbitrary shapes? Which method can be explained in less than a minute, and yet they'll remember how to do it after you leave and move on to the next student?

There are three obvious candidates for a general-purpose selection tool: the intelligent scissors, the paths tool, and the quickmask. We had a miscommunication in one of the early classes and didn't discuss which technique to teach, so I taught some students the paths tool while Christian was teaching others the iscissors. I found that both methods had some serious problems.

With Bezier paths, it's easy to click points around your object. Students get a little flustered the first few times they accidentally drag rather than click and drag handles appear, but they can get over that. The part that's difficult comes at the end, where they have to click Path to Selection, then Feather as a separate step (they don't need to feather the first time, but eventually they'll need it). And then there's the problem that the path as well as the selection remains visible, a distraction that they don't understand.

When I saw that Christian had been teaching some students the iscissors while I was teaching others paths, I thought, gee, good idea. Iscissors should be more straightforward, no? Well, no, as it turns out. New students have great difficulty making an iscissors selection. They're fine as long as they're clicking their points; the problem comes when they get to the last point, when in order to make a selection you must click carefully on your first point, then click again inside the figure. A lot of students don't understand this no matter how many times you explain: they don't remember which was their first point (it doesn't look any different from the others), they can't see it anyway (it usually doesn't contrast much with the image), and they can't tell whether they clicked it successfully.

At that point they try to click inside the image and get a spurious extra point -- and then they panic and start clicking all over the place, ending up with a mess that is (as far as I've been able to tell) unrecoverable. The only fix is to toss out that figure and start over, but even that isn't easy to do (click on another tool then back on the iscissors tool button). Basically, the iscissors tool is far too confusing and most students need to be personally walked through it at least three times (some of them a lot more than that) before they get it.

Anyone who's read my writing on GIMP probably knows that I'm a quickmask zealot. I'm a born again quickmask prophet: I used GIMP for years without really understanding the quickmask, and when I finally grokked it, it made a huge difference in ease of selection. I sometimes joke that "the quickmask changed my life", and that's hyperbole, or course; but it sure did change my GIMP editing. People seem to fear the quickmask so I usually don't present it first, but maybe I should. These students are very eager and competent at painting, and I think they'd take to the quickmask very easily with far fewer stumbles than the other two methods have given them.

There's one other variant of shaped selection that I didn't list: the lasso tool in add and subtract mode. The lasso tool is terrifically hard to use to try to select a whole figure from an image. You'd have to have a preternaturally steady hand, plus you can't zoom in and scroll around since the whole figure has to be completed in one movement. But what you can do is make a rough selection with the lasso, understanding that you'll have some errors; then alternate between Add mode and Subtract mode as you use the lasso on smaller areas to get the selection just right. It's nearly as easy as the quickmask, and doesn't require a big conceptual shift. The only reason I'm leery is that I suspect the three modes would confuse a lot of students -- especially since the mode buttons have no labels, merely tooltips.

While I'm on the topic, there's another issue that gives the students trouble besides selection: the floating selection that results from a paste. There's really no way to explain to a schoolkid why it's there (heck, maybe some day someone will explain that to me). And it's useless to try to get them to keep their Layers dialogs visible. (They don't even keep the toolbox visible most of the time; it's always covered by image windows. Most of these Edubuntu machines are working at 800x600 resolution, and there just isn't room on the screen for the normal GIMP window collection.)

So I try to drill them that "Every time you paste, you have to find the Layers window and click that button on the bottom left." Understandably, they often forget that step, then get into trouble because they can't see all their pasted layer, or some functions are greyed out.

Aside from selection and paste, the students seem to cope with GIMP remarkably well. Some of them have been exploring the menus for fun plug-ins, others are trying different patterns to make interesting backgrounds, and one even discovered how to make interesting effects with some of the specialized gradients. At the beginning I wondered if teaching GIMP might not be too ambitious, and maybe something simple like Tux Paint might be better. But GIMP is working out just fine except for those few stumbling blocks. The kids have a refreshing willingness to explore and try things, and the result is a whole lot of really fun images.

Tags: , ,
[ 23:44 Apr 12, 2008    More gimp | permalink to this entry | comments ]

Fri, 11 Apr 2008

A booth with a view

A local chain Mexican restaurant, Acapulco, has window booths that overlook a tiny fake pond belonging to an apartment complex. The pond is popular with mallards and Canada geese, birds that don't mind making their home in the back yard of an apartment complex. If you get there early enough to get a window booth, you can get a nice view of the birds over your meal.

I love watching the mallards splash down. Ducks are heavy birds, with fairly small wings. They have one flying speed: fast. So landing can be a bit tricky. Generally they come in with a long, shallow glide, big webbed feet outstretched. The goal is to get the feet down smoothly and use them as waterskis until you've bled off enough speed to drop down into a nice, sedate swimming position.

This is just as hard as it sounds, and the young ducks aren't too good at it, so over the course of a meal you get to watch lots of crash-landings where the waterski technique doesn't quite work and the duck goes splashing face-first into the water.

A couple of weeks ago, I got an interesting view of another aspect of duck life: sleeping. A mallard pair floated together, side by side. The female had her nead neatly tucked backward into the top of one of her wings, but the male had his head in almost a normal swimming position. The clue that he, too, was asleep was that the head never moved. But as he drifted closer, I could see something else interesting. His eye (the one on our side -- I couldn't see the other eye) alternated every two seconds between fully open, and closed with a nictitating membrate. So the eye would be open and dark for two seconds, then cloudy blue for two seconds, then open for two seconds ... quite odd!

Last night, we had an even better view than that. On the tiny rock in the middle of the pond sat a Canada goose, and next to her (I say "her" as if I could tell the difference) were goslings! Tiny, yellow, fluffy ones, lots of them, too many to count. And they must have been just hatched, because there was at least one egg still visible in the nest. The goslings were active, swarming around the mother and climbing around the rock.

But one of them was bolder than the others -- it wasn't on the rock, but in the water next to (I can only presume) the other parent. The adult goose glided sedately across the pond, the tiny gosling keeping up without seeming to try very hard.

Eventually they got to the edge of the lake, where the parent got out of the water and walked up the rocky beach to the manicured grass, where he sat down to rest. The gosling followed, clambering energetically up the rocks of the beach. But when the older goose settled down in the grass, the gosling wasn't content. It climbed up and down, from the water's edge to the grass and back to the water's edge, for the next fifteen minutes while the parent rested. Finally the adult got up and went back to the water, closely followed by the chick, and they went back to tandem swimming.

Meanwhile, the goose on the rock had settled back down on the remaining egg, and the rest of the goslings quieted down and cuddled up next to her. A lovely and tranquil scene.

South bay bird fans, check out Acapulco. Maybe the last egg has hatched by now! I never expected to wish I'd brought binoculars to a Mexican restaurant ...

Tags: , ,
[ 10:46 Apr 11, 2008    More nature/birds | permalink to this entry | comments ]

Thu, 10 Apr 2008

A minimal xorg.conf

Dave has been experimenting with xorg configuration lately -- trying to figure out why the latest Xorg no longer supports 1600x1200 on his monitor. (I've looked for bug reports and found gazillions of them, all blaming it on the video card but involving three different makes of video card, so color me skeptical.)

Anyway, part of this has involved taking out parts of his /etc/X11/xorg.conf file to see which parts might be causing the problem, and he's found something interesting.

What do you suppose is the minimal useful xorg.conf file? You might suppose, oh, screen and monitor sections, an input section for the keyboard and another one for a generic mouse, and that might be all you need ... right?

Okay, try it. Let's start with a really minimal file -- nothing -- and gradually add sections. To try it, make a backup of your current xorg.conf, then zero out the file:

cd /etc/X11
mv xorg.conf xorg.conf.sav
cp /dev/null xorg.conf

Now exit X if you hadn't already, and start it up again (or let gdm do it for you). Be prepared to do repairs from the console in case X doesn't start up: e.g. sudo cp /etc/X11/xorg.conf.bak /etc/X11/xorg.conf

What happened?

In my case, on the laptop running Hardy beta, X starts right up and looks just the same as it did before.

xorg.conf -- who needs it?

A specious question, of course, which has a perfectly good answer: anyone who needs a resolution other than whatever xorg picks as the default; anyone with additional hardware, like a wacom tablet; anyone who wants customizations like XkbOptions = ctrl:nocaps. There are lots of reasons to have an xorg.conf. But it's fun to know that at least on some machines, it's possible to run without one.

Update: turns out this is part of Ubuntu's new BulletProof X feature. It doesn't work on other distros or older versions. Thanks to James D for the tip.

Tags: ,
[ 11:25 Apr 10, 2008    More linux | permalink to this entry | comments ]

k3b breaks without hal

I burned a CD for the Ubuntu hardy beta alternate installer. I used k3b since that's been a good, fairly reliable burning app with a well designed UI -- I've been using it for years despite not running a KDE desktop. I selected "Burn CD Image", reduced the speed (burning apps are always wildly optimistic about speed, with the result that they create a lot of coasters) and checked the box for "verify contents after burning".

The burn went fine, and k3b ejected the CD, then sucked it back in again for the verification stage. At that point k3b started spewing lots of errors to the terminal, things like "/dev/hdd: READ 10 failed!" and "Failed to init HAL context!" repeated many times.

How annoying! k3b has added a new dependency on hal, and although it can burn a CD just fine, without hal it then forgets where the CD drive was so it can read the CD back in to verify it.

Fortunately dd /dev/cdrw | md5sum worked fine to verify that the burn was correct. I guess it's time to investigate other CD burning programs.

Tags: ,
[ 11:04 Apr 10, 2008    More linux | permalink to this entry | comments ]

Tue, 08 Apr 2008

Wrapping plaintext files in Firefox

A friend pointed me to a story she'd written. It was online as a .txt file. Unfortunately, it had no line breaks, and Firefox presented it with a horizontal scrollbar and no option to wrap the text to fit in the browser window.

But I was sure that was a long-solved problem -- surely there must be a userContent.css rule or a bookmarklet to handle text with long lines. The trick was to come up with the right Google query. Like this one: firefox OR mozilla wrap text userContent OR bookmarklet

I settled on the simple CSS rule from Tero Karvinen's page on Making preformated <pre> text wrap in CSS3, Mozilla, Opera and IE:

pre {
 white-space: -moz-pre-wrap !important;
Add it to chrome/userContent.css and you're done.

But some people might prefer not to apply the rule to all text. If you'd prefer a rule that can be applied at will, a bookmarklet would be better. Like the word wrap bookmarklet from Return of the Sasquatch or the one from Jesse Ruderman's Bookmarklets for Zapping Annoyances collection.

Tags: , , , , ,
[ 11:47 Apr 08, 2008    More tech/web | permalink to this entry | comments ]

Mon, 07 Apr 2008

Ubuntu "Hardy Heron"

On a lunchtime bird walk on Monday I saw one blue heron and at least five green herons (very unusuual to see so many of those). Maybe that helped prepare me for installing the latest Ubuntu beta, "Hardy Heron", Monday afternoon.

I was trying the beta primarily in the hope that it would fix a serious video out regression that appeared in Gutsy (the current Ubuntu) in January. My beloved old Vaio SR17 laptop can't switch video signals on the fly like some laptops can; I've always needed to boot it with an external monitor or projector connected. But as long as it saw a monitor at boot time, it would remember that state through many suspend cycles, so I could come out of suspend, plug in to a projector and be ready to go. But beginning some time in late January, somehow Gutsy started doing something that turned off the video signal when suspending. To talk to a projector, I could reboot with the projector connected (I hate making an audience watch that! and besides, it takes away the magic). I also discovered that switching to one of the alternate consoles, then back (ctl-alt-F2 ctl-alt-F7) got a signal going out on the video port -- but I found out the hard way, in front of an audience, that it was only a 640x480 signal, not the 1024x768 signal I expected. Not pretty! I could either go back to Feisty ... or try upgrading to Hardy.

I've already written about the handy debootstrap lightweight install process I used. (I did try the official Hardy "alternate installer" disk first, but after finishing package installation it got into a spin lock trying to configure kernel modules, so I had to pull the plug and try another approach.)

This left me with a system that was very minimal indeed, so I spent the next few hours installing packages, starting with tcsh, vim (Ubuntu's minimal install has something called vim, but it's not actually vim so you tend to get lots of errors about parsing your .vimrc until you install the real vim), acpi and acpi-support (for suspending), and the window system: xorg and friends. To get xorg, I started with:

apt-get install xserver-xorg-video-savage xbase-clients openbox xloadimage xterm

Then there was the usual exercise of aptitude search font and installing everything on that list that seemed relevant to European languages (I don't really need to scroll through dozens of Tamil, Thai, Devanagari and Bangla fonts every time I'm looking for a fancy cursive in GIMP).

But I hit a problem with that pretty early on: turns out most of the fonts I installed weren't actually showing up in xlsfonts, xfontsel, gtkfontsel, or, most important, the little xlib program I'm using for a talk I need to give in a couple weeks. I filed it as bug 212669, but kept working on it, and when a clever person on #ubuntu+1 ("redwhitewaldo") suggested I take a look at the x-ttcidfont-conf README, that gave me enough clue to get me the rest of the way. Turns out there's a Debian bug with the solution, and the workaround is easy until the Ubuntu folks pick up the update.

I hit a few other problems, like the PCMCIA/udev problem I've described elsewhere ... but mostly, my debootstrapped Hardy Heron is working quite well.

And in case you're wondering whether Hardy fixed the video signal problem, I'm happy to say it does. Video out is working just fine.

Tags: , , , ,
[ 19:31 Apr 07, 2008    More linux/install | permalink to this entry | comments ]

Sun, 06 Apr 2008


Some time ago, I wished for a simple Linux "Tarball installer", something that could install a minimal install of a Linux distribution onto an existing partition or directory, skipping all the flaky and error-prone hardware-guessing that installers do.

It turns out Debian (and therefore also Ubuntu) has had this for years, and it's totally cool. It's called debootstrap.

Some folks on the #ubuntu+1 channel told me about it, and I found a nice clear howto article on how to use it for Debian. It works just the same for Ubuntu.

First, get the .deb package for the debootstrap you want to use. Here's debootstrap for Ubuntu Hardy Heron. Install it with dpkg -i. Then run it, giving it the name of the system you want to install and the directory (or mounted partition) where you want to install it. Like this: debootstrap hardy /mnt/hda3

That's all! It fetches the files it needs from the online repositories. It takes no time at all -- this really is a minimal system.

Then you need to do some fiddling to turn it into a bootable system. That includes (all paths relative to the newly installed filesystem unless otherwise stated):

Now you're read to reboot into the new system. Of course, since this is a very minimal system, you have a lot more work to do. Hardly anything is installed, and nothing has been configured for you. Some things may be challenging (for example, as I write this, X is installed but most of the fonts aren't showing up properly, which may be a bug in Hardy).

Anyway, you can get a good start by mounting your old system's root directory and copying some starter files from there, starting with these:

Tags: , ,
[ 13:54 Apr 06, 2008    More linux/install | permalink to this entry | comments ]

Fri, 04 Apr 2008

Handling a network card automatically: Calling ifup from udev

I'm experimenting with Ubuntu's "Hardy Heron" beta on the laptop, and one problem I've hit is that it never configures my network card properly.

The card is a cardbus 3Com card that uses the 3c59x driver. When I plug it in, or when I boot or resume after a suspend, the card ends up in a state where it shows up in ifconfig eth0, but it isn't marked UP. ifup eth0 says it's already up; ifdown eth0 complains error: SIOCDELRT: No such process but afterward, I can run ifup eth0 and this time it works. I've made an alias, net, that does sudo ifdown eth0; sudo ifup eth0. That's silly -- I wanted to fix it so it happened automatically.

Unfortunately, there's nothing written anywhere on debugging udev. I fiddled a little with udevmonitor and udevtest /class/net/eth0 and it looked like udev was in fact running the ifup rule in /etc/udev/rules.d/85-ifupdown.rules, which calls: /sbin/start-stop-daemon --start --background --pid file /var/run/network/bogus --startas /sbin/ifup -- --allow auto $env{INTERFACE} So I tried running that by hand (with $env{INTERFACE} being eth0) and, indeed, it didn't bring the interface up.

But that suggested a fix: how about adding --force to that ifup line? I don't know why the card is already in a state where ifup doesn't want to handle it, but it is, and maybe --force would fix it. Sure enough: that worked fine, and it even works when resuming after a suspend.

I filed bug 211955 including a description of the fix. Maybe there's some reason for not wanting to use --force in 85-ifupdown (why wouldn't you always want to configure a network card when it's added and is specified as auto and allow-hotplug in /etc/network/interfaces?) but if so, maybe someone will suggest a better fix.

Tags: , , ,
[ 14:41 Apr 04, 2008    More linux | permalink to this entry | comments ]

Thu, 03 Apr 2008


We had some new visitors to our office door this evening: a pair of raccoons! We've had opossums here a few times, but this is the first time we've seen raccoons here.

They're curious and smart: the less fearful one stands up on hind legs and takes long looks at each of us, then decides we don't seem too threatening. Then it uses one "hand" to scoop food from the shelf into the other hand, and retreats back to where the water dish is.

Its companion is a little more nervous: it comes to the door and looks in, then backs off to where it's just at the edge of the door peeking in.

They've already figured out that when the door opens, that's when more food appears, so don't retreat too far. It takes squirrels ages to get over running away when we open the door to add more food. (It may be an ominous sign that we also saw the bolder raccoon stand up tall on its hind legs and reach toward the door latch.)

They've also figured out something else: they like chocolate chip cookies a lot more than nuts.

Tags: , ,
[ 23:55 Apr 03, 2008    More nature | permalink to this entry | comments ]