Linux

Today I faced an interesting Linux problem that made me learn a couple of things I'd like to share. At first, we found an issue on a Thinkpad X301 notebook that was fixed in a newer BIOS version. So we wanted to do a BIOS update. Lenovo provides BIOS updates either for Windows or as bootable ISO CD-images. But the device had no CD-drive and only Linux installed. First we tried unetbootin, a tool to create bootable USB sticks out of ISO-Images. That didn't work.
So I had a deeper look at the ISO. What puzzled me was that when mounting it as a loopback device, there were no files on it. After some research I learned that there are different ways to create bootable CDs and one of them is the El Torito extension. It places an image of a harddisk on the CD, when booting, the image is loaded into memory and an OS can be executed (this probably only works for quite simple OSes like DOS, the Lenovo BIOS Upgrade disk is based on PC-DOS). There's a small PERL-script called geteltorito that is able to extract such images from ISO files.
It's possible to boot such harddisk images with grub and memdisk (part of syslinux). Install syslinux, place the file memdisk into /boot (found in /usr/lib/syslinux/ or /usr/share/syslinux/) and add something like this to your grub config:

Or for grub2:

Now you can select bios update in your boot menu and it should boot the BIOS upgrade utility.

(Note that this does not work for all Lenovo BIOS updates, only for those using an El Torito harddisk image - you can mount your iso with mount -o loop [path_to_iso] [mount_path] to check, if there are any files, this method is not for you)

Ich stand heute vor dem Problem, ein Video aus der ARD-Mediathek herunterladen zu wollen. Die gibt es meistens nur noch als Flash und ohne Download-Link.

Die Videos werden über RTMP übertragen, was ein Flash-eigenes Videostreaming-Protokoll ist. Im gulli-Forum fand ich eine Anleitung. Ich habe darauf basierend ein kleines Skript ardget geschrieben, mit dem man das bequem erledigen kann. Aufzurufen einfach über
ardget "[URL der Mediathek]"

Die Anführungszeichen sind notwendig, weil die URLs &-Zeichen enthalten, die sonst von der Shell fehlinterpretiert werden. Da die Videos teilweise mit Javascript-URLs verlinkt sind, filtere ich das auch entsprechend, man kann also den kompletten javascript: beginnenden Link übergeben. Benötigt wird entweder flvstreamer oder rtmpdump, sollte ansonsten in jeder gängigen Unix-Shell funktionieren.