Shallow Thoughts : : Feb

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

Sun, 05 Feb 2006

Auto-Login, and X Without gdm

I've been unable to persuade Ubuntu's "Dapper Drake" to log me in automatically via gdm. My desktop background flashes briefly during the login process, then vanishes; it appears that it actually is logging me in briefly, then immediately logging me out and presenting me with the normal gdm login screen.

I never liked gdm much anyway. It's heavyweight and it interferes with seeing shutdown messages. The only reason I was using it on Hoary was for autologin, and with that reason gone, I uninstalled it.

But that presented an interesting problem: it turns out that Dapper doesn't actually allow users to run X. The error message is:

Unable to open wrapper config file /etc/X11/Xwrapper.config
X: user not authorized to run the X server, aborting.
The fix turned out to be trivial: make the X server setuid and setgid (chmod 6755 /usr/bin/X). Mode 4755 (setuid only, no setgid) also works, but other Debian systems seem to set both bits.

The next question was how to implement auto-login without gdm or kdm. I had already found a useful Linux Gazette article on the subject. The gist is that you compile a short C program that calls login with your username, then you call getty with your new program as the "alternate login program". Now, I have nothing against C, but wouldn't a script be easier?

It turns out a script works too. Replace the tty1 line in /etc/inittab with a line like:

1:2345:respawn:/sbin/getty -n -l /usr/bin/myloginscript 38400 tty1
where the script in question looks like:
#! /bin/sh
/bin/login -f username

At first, I tried an even simpler approach:

1:2345:respawn:/bin/login -f username

That logged me in, but I ended up on /dev/console instead of /dev/tty1, with a message that I had no access to the tty and therefore wouldn't be able to use job control. X didn't work either. The getty is needed in order to switch control from /dev/console to a real virtual terminal like /dev/tty1.

Of course, running X automatically once you're logged in is trivial, just a line or three added to .login or .profile (see the Linux Gazette article referenced above for an example).

It works great, it's very fast, plus I can watch shutdown messages again. Nice!

Update 9/9/2006: the Linux Gazette article isn't accessible any more (apparently Linux Journal bought them and made the old articles inaccessible). But here's an example of what I do in my .login on Dapper -- this is for tcsh, so bash users subtitute "fi" for "endif":

    if ($tty == tty1) then
        startx
    endif

Tags: , ,
[ 10:53 Feb 05, 2006    More linux | permalink to this entry | comments ]

Sat, 04 Feb 2006

Ubuntu "Dapper Drake"

I've been meaning to upgrade my desktop machine from Ubuntu's "Hoary Hedgehog" release for some time -- most notably so that I can get the various packages needed to run GTK 2.8, which is now required to build the most current GIMP.

Although I'm having good success with "Breezy Badger", the stable Ubuntu successor to "Hoary", on my laptop, Breezy is already borderline as far as GIMP requirements, and that can only get worse. Since I do more development on the desktop, I figured it was worth trying one of the pre-released versions of Ubuntu's next release, "Dapper Drake".

Wins over hoary and breezy: it handles my multiple flash card reader automatically (on hoary and breezy I had to hack the udev configuration file to make it work).

I've had a few glitches, starting with the first auto-update wanting to install a bunch of packages that didn't actually exist on the server. This persisted for about a week, during which I got a list of 404s and "packages held back" warnings every time I updated or installed anything. It didn't seem to hurt anything -- just a minor irritant -- and it did eventually get fixed. That's life with an unstable distribution.

Dapper has the same problem that hoary and breezy have with hald polling the hard disk every few seconds (bug 27323). In addition, hald seems to spawn a rather large number of hald-addon-storage processes (probably to handle the built-in multi flash card reader). (Uncommenting the storage.automount_enabled_hint in /etc/hal/fdi/policy/preferences.fdi didn't help.) Killing hald (and nuking /usr/sbin/hald so it won't restart) solves both these problems, but it also stops hotplugged USB devices from working: apparently Dapper has switched to using hal instead of hotplug for USB. Ouch! In any case, hald came back on a dist-upgrade so it looks like I'll have to find a more creative solution.

The printing packages have problems. I tried to add my printer via the CUPS web interface, but apparently it didn't install any printer drivers by default, and it's not at all obvious where to get them. The drivers are there, in /usr/share/cups/model/gutenprint/5.0/en, but dapper's cups apparently isn't looking there. I eventually got around the problem by uncompressing the ppd file and pointing CUPS directly at /usr/share/cups/model/gutenprint/5.0/en/stp-escp2-c86.5.0.ppd. (Filed bug 30178.)

Dapper's ImageMagick has a bug in the composite command: basically, you can't combine two images at all. So I have to generate web page thumbnails on another machine until that's fixed.

gdm refuses to set up my user for auto-login, and I hit an interesting localization issue involving GIMP (I'll report on those issues separately).

Most other things work pretty well. Dapper has a decent set of multimedia apps and codecs, and its kernel and udev setup seem to work fine (it can't suspend my desktop machine, but neither can any other distro, and I don't really need that anyway). Except for the hald problem, Dapper looks like a very usable system.

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[ 18:27 Feb 04, 2006    More linux | permalink to this entry | comments ]

Thu, 02 Feb 2006

Suburban Squirrels

In early December, a squirrel staked out our yard as part of his territory. We encouraged him with nuts. He has a notch in one ear, so I called him "Notch".

Later that month, another squirrel showed up. Sometimes Notch chased the new squirrel (especially when food was involved), but at other times they seemed to be playing in a friendly way. Apparently December is breeding time for squirrels.

There's no easy way to identify the gender of grey squirrels (at least from a distance), so we arbitrarily decided that the larger, tougher and more territorial Notch was a male, and the newcomer must be female. Dave dubbed her "Nonotchka".

(Of course we're hoping that in a few months it will become obvious which one is actually the female, and soon afterward we will have little squirrels to watch.)

Both Notch and Nonotchka have become rather tame (though not quite to the point of taking food from our hands), and we've been able to get some decent (though not spectacular) photos while feeding them. Unfortunately, the final review process for the GIMP book got in the way of organizing the photos or writing squirrel essays, and I'm only now starting to catch up.

So here they are: our Suburban Squirrels.

Tags: , ,
[ 14:57 Feb 02, 2006    More nature/squirrels | permalink to this entry | comments ]

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