A Couple Of Things…

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The BrainwreckedTech’s Wiki has guides for setting up a desktop with Arch, Ubuntu, or Windows; setting up a server; and advanced tweaks and scripts. Not much there now, but you can contribute there, too!

Problems With Arch Package Signing

Arch Linux finally has package signing. However, if you follow the directions blindly, you may miss important details. This will usually lead to error messages about keys being of marginal trust or no trust at all.

The code posted on Arch’s wiki page for pacman-key gives you the code you need to use the five main keys used to sign everything else.

for key in FFF979E7 CDFD6BB0 4C7EA887 6AC6A4C2 824B18E8; do
     pacman-key --recv-keys $key
     pacman-key --lsign-key $key
     printf 'trust\n3\nquit\n' | gpg --homedir /etc/pacman.d/gnupg/ \
         --no-permission-warning --command-fd 0 --edit-key $key
done

But if you’re not paying attention, you’ll miss the fact that some keys failed to import due to server issues.

Using Rsync With Your Web Host

This was one of those “Holy crap this is so frickin’ awesome who needs Viagra this here makes my…” moments for me. If this seems pedestrian to you, keep in mind I haven’t used third-party hosting since around the Y2K debacle, when FTP was the gold standard. Nowadays a lot of web hosts provide SSH access.

FTP is still nice, but rsync presents a much more elegant solution. Unfortunately, rsync is something most Windows users don’t know about. Microsoft includes no equivalent, so you can either attempt to get rsync and cygwin working on your system, or grab a copy of DeltaCopy…which is made by a company that makes a competing product.

But if you’re running Linux you can forget all that nonsense and get to the good stuff.

Copying from the host to your local computer:

rsync -avz -e “ssh -p nnnn” [user]@[domain]:[remote dir] [local dir]

You can then edit files locally using your editor(s) of choice. Heck, you can even run your own web server to test changes if you want. You can even run that web server in a VM if you don’t want the potential pitfalls of having a web server running on you computer.

Copying from your computer to the host:

rsync -avz -e “ssh -p nnnn” [local dir] [user]@[domain]:[remote dir]

The only thing to watch out for is that this is so easy that you become lazy. Syncing an entire directory for changes to just one file will consume way more bandwidth than just specifying that one file. For exampe: after making some small tweaks to a test HTML file I noted I was transferring 89K of data for the sake of updating a 2K file.

HOWTO: Convert VDIs Between Fixed-Sized and Dynamic In VirtualBox

While there is no way to actually switch a VDI between fixed-size and dynamic, you can clone the existing VDI into a new one with different settings with VBoxManage.

VBoxManage clonehd [ old-fixed-VDI ] [ new-dynamic-VDI ] --variant Standard
VBoxManage clonehd [ old-dynamic-VDI ] [ new-fixed-VDI ] --variant Fixed

If you want to expand the capacity of a VDI, you can do so with

VBoxManage modifyhd [ VDI-image ] --resize [ megabytes ]

Resizing only works for dynamic VDI images. However, you can combine the resize information with the conversion information to expand fixed-size VDIs. (E.g., convert a fixed-size image to dynamic, expand it, and then convert the dynamic image back to a fixed-size image.)

If you want to compact the image as much a possibly, be sure to zero out the free space. This can be done in Linux by using the dd command to write endless zeros to a file and then deleting that file. (With the caveat of the reserved space of EXT and other file systems.)

Easily Switch Aspect Ratios in MPlayer

Wouldn’t you like to switch aspect ratios in MPlayer? Sure, a lot of front-ends do it, but sometimes you want to run MPlayer directly. For myself, it’s all about getting proper crop settings for DVD rips. But I’ve also had a few video files with incorrect or missing aspect ratio info.

Just put this into ~/.mplayer/input.conf:

F1 switch_ratio 0
F2 switch_ratio 1.3333
F3 switch_ratio 1.7778
F4 switch_ratio 1.85
F5 switch_ratio 2.3

Source/Credit: http://lists.mplayerhq.hu/pipermail/mplayer-users/2005-November/056709.html

Arch Update Notifications Using Cron

One of the great things about Arch is its hands-off approach and KISS approach. Unfortunately, that can also be one of its greatest killjoys.

Update notifications fall victim to this approach. If you’re left to build an Arch system to your own accord, how can the Arch devs know what will work on your system and what won’t? Therefore, instead of worrying about GNOME vs KDE vs Any Other Desktop Environment (that is, if you’re running a GUI at all) and possibly forcing dependencies you don’t want, no package management system will ever be officially supported by Arch outside of pacman.

WARNING: Your NIC (or Driver) Might Lie About MTU

This is one for the ages. I had two problems creep in at once. The first was shoddy NFS performance. I Googled my way across the internet for troubleshooting and performance tips. However, nothing seemed to improve the situation. While that was going on, I noticed the second problem — one of the hard drives was failing its own SMART test.

I was already up late, and the last thing I wanted to be bothered with was finding out which drive it was, going the manufacturer’s site to download their drive diagnostic boot CD, getting the warranty return code, and starting the RMA process. But I hung in there and pulled through.

After some sleep, I tried tinkering with a few more networking settings. I was still coming up with nothing, so I ordered a Cat6 cross-over cable so I could at least rule either way on the cabling and network switch.

BUG: libdvdread Can’t Seek To Block On Second Layer

PROBLEM: When accessing the drive directly, libdvdread cannot seek to blocks that are on the second layer of a DVD.

EXPECTATION: It shouldn’t matter if the device is mounted or not.

RESULT: It does matter, for reasons I haven’t found out yet.

SOLUTION: Mount the device somewhere on the file system. Everything should now work properly, wether you use the block device directly or the mount point.

TO REPRODUCE: Use any application that uses libdvdread. (In this example I’ll use MPlayer.) DO NOT MOUNT THE DEVICE or UNMOUNT THE DEVICE if using some form of automatic mounting for optical discs. Seek to a specific chapter until libdvdread fails.

mplayer -dvd-device /dev/sr0 dvd://[n] -chapter [x]
mplayer -dvd-device /dev/sr0 dvd://[n] -chapter [x+1]
mplayer -dvd-device /dev/sr0 dvd://[n] -chapter [x+2]
etc.

Eventually you’ll get to a point where playback does not start, and libdvdread will give the following error:

libdvdread: Can't seek to block xxxxxxxx

Note that the following will play to the end until a seek attempt is made that attemtps to seek to a block on the second layer:

mplayer -dvd-device /dev/sr0 dvd://[n] -chapter [last-working-chapter]

Mount the device somewhere:

mount -rt udf /dev/sr0 /media/dvd

Now use MPlayer to start play from the first non-working chapter.

mplayer -dvd-device [ /dev/sr0 | /media/dvd ] dvd://[n] \
-chapter [previously-nonworking-chapter]

Playback should be fine.

NVIDIA, HDTV, and Overscanning

First off, an apology for not writing in a long time, but since I’ve switched to Arch Linux I really haven’t had any brain-wrecking problems to write about. But you know, that just means the next problem I run across is going to be just that much bigger, right?

I had a couple of issues with my HDTV.

Switching To Arch Linux — Part 2

So I was ready to give Arch another shot. I had in mind exactly what I wanted for my desktop — mostly lightweight application save for some heavy hitters. LXDE provides a lot of lightweight applications, I was sure I could find some replacement apps for whatever LXDE was missing, and the the heavy hitters could be bolted on with ease.

Of course, almost nothing went according to plan.

Switching To Arch Linux – Part 1

It’s been a long time, but I finally have an adventure in Linux to report on.