Category Archives: programming

Query recently installed rpm’s

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Last night I was fooling around with lwjgl (nice lib btw), when suddenly I started getting the following exception:

org.lwjgl.LWJGLException: Could not choose GLX13 config
	at org.lwjgl.opengl.LinuxDisplayPeerInfo.initDefaultPeerInfo(Native Method)
	at org.lwjgl.opengl.LinuxDisplayPeerInfo.(LinuxDisplayPeerInfo.java:61)
	at org.lwjgl.opengl.LinuxDisplay.createPeerInfo(LinuxDisplay.java:782)
	at org.lwjgl.opengl.DrawableGL.setPixelFormat(DrawableGL.java:61)
	at org.lwjgl.opengl.Display.create(Display.java:871)
	at org.lwjgl.opengl.Display.create(Display.java:782)
	at org.lwjgl.opengl.Display.create(Display.java:764)

I googled and some Minecraft stuff turned up (seems it uses lwjgl as well), but only with mysterious “solutions”. I thought it was because I tried to run it from console (it ran fine before in IntelliJ), but it stopped working there too. Then I suspected mixing openjdk compiled code run by sun jre was the problem (seems lwjgl requires sun jre). Than I fumbled around with the java.library.path variable because it looked like a 64bit vs 32bit issue. NONE OF THAT!
I screwed up and it was late, so I decided to admit my defeat and go to bed.

Today I started my suse box, suddenly I realized my KDE desktop effects were disabled. Nvidia driver borked? Reinstalled my nvidia, even rebooted, all in vein!
I checked hardware acceleration with Urban Terror, smooth gaming!

Then I started to retrace my steps of last night.. I tried to install glc which in the past had proven to be quite a decent opengl capture program for linux.

I checked my repos and noticed I accidentally installed the 12.1 version! Uninstalling that does not fix it of course, probably some dependency messed up things good (although still quite subtle to keep everything else working ;) ).

I finally come to the point of this post ;) I wanted to know what I installed last night in the late hours that seriously borked my system.

Turns out rpm has a neat option just for that: –last !
So it goes like this:

# rpm -qa --last | less

yields amongst others:

libcurl4-7.21.2-10.11.1                       Mon 30 Jan 2012 11:06:02 PM CET
libcurl4-32bit-7.21.2-10.11.1                 Mon 30 Jan 2012 11:06:02 PM CET
glibc-locale-2.14.1-14.18.1                   Mon 30 Jan 2012 01:46:16 AM CET
glibc-devel-2.14.1-14.18.1                    Mon 30 Jan 2012 01:46:11 AM CET
parallel-printer-support-1.00-5.1             Mon 30 Jan 2012 01:46:10 AM CET
glibc-2.14.1-14.18.1                          Mon 30 Jan 2012 01:46:08 AM CET
gpg-pubkey-b185393d-47965930                  Mon 30 Jan 2012 01:45:55 AM CET
phpMyAdmin-3.4.9-30.1                         Thu 19 Jan 2012 09:22:30 PM CET

I managed to fubar my glibc :) culprit found! Reverting this to the previous version fixed it!

Android USB debugging on openSUSE 11.4

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Debugging your android app using a hardware device has several advantages, ie faster and more testing possibilities. On windows you have to install a custom USB driver, on linux it’s a matter of configuring your udev rules:

  • add a rules files in /etc/udev/rules.d , ie 44-android.rules
  • enter a line like this: 
    SUBSYSTEM=="usb", ATTR{idVendor}=="0bb4", MODE="0666", GROUP="users"

    and adapt the vendor id using this table.

  • Reload udev rules: udevadm control --reload-rules

When you run adb devices, it should now list your device:

List of devices attached 
emulator-5554   device
SH14FPL06953    device

Before, you would rather have something like this:

List of devices attached 
emulator-5554   device
????????????    no permissions

On succesful connection, the system log shows something like: 

kernel: [11172.551464] usb 2-1: USB disconnect, address 4
kernel: [11178.813044] usb 2-1: new high speed USB device using ehci_hcd and address 5
kernel: [11178.942137] usb 2-1: New USB device found, idVendor=0bb4, idProduct=0c87
kernel: [11178.942150] usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
kernel: [11178.942157] usb 2-1: Product: Android Phone
kernel: [11178.942162] usb 2-1: Manufacturer: HTC
kernel: [11178.942166] usb 2-1: SerialNumber: SH14FPL06953
kernel: [11178.943867] scsi8 : usb-storage 2-1:1.0
mtp-probe: checking bus 2, device 5: "/sys/devices/pci0000:00/0000:00:04.1/usb2/2-1"
mtp-probe: bus: 2, device: 5 was not an MTP device
kernel: [11179.953172] scsi 8:0:0:0: Direct-Access     HTC      Android Phone    0100 PQ: 0 ANSI: 2
kernel: [11179.953375] sd 8:0:0:0: Attached scsi generic sg4 type 0
kernel: [11179.961631] sd 8:0:0:0: [sdd] Attached SCSI removable disk

Note that it seems normal that a usb storage device is detected, although I did not have it enabled on the phone.

Git: how to tag old commit

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Another noob git tip. Tagging with git is easy and I won’t duplicate another explanation here. But suppose you want to tag a commit which you already pushed to another repo. When you push, nothing happens. I had tagged before, so I thought the problem was that I wanted to tag a commit which I already pushed.

But the trick to know here is: push simply does not push tags by default. You have to specify an option. So any tag you would want to share, on your last commit or any other commit, you would have to push explicitly:

git push origin <mytag>

or if you’d want to sync all tags in one go:

git push --tags origin

So, the title of this blog post was actually a trick question ;)

Git: set up remote branch tracking post factum

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I often have the following scenario:
- create local repository/branch
- create gitorious project/repository
- push branch to gitorious

This way you end up with your local branch not tracking the remote one. You know you’re not tracking when you have to specify the branch every time you push/pull and when you don’t see how much commits you are ahead of the remote. It is a matter of setting up the correct tracking configuration, something like this for the master branch:

git config branch.master.remote origin
git config branch.master.merge refs/heads/master

However, I just discovered that since git 1.7 there is now a command for this:

git branch --set-upstream master origin/master

much easier to remember!

I <3 libpcap

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A few years ago, I wrote a small app showing the open network connections (announcement following shortly). I never figured out how to measure transfer rates over the connections since the kernel does not seem to provide this info through the /proc filesystem (only some data queue length which is related to kernel mem usage).

Today we all know and love iftop, but where does it get that info? Simple: pcap! Out of curiosity, I checked out the libpcap docs to see how hard it would be to get started. Turned out to be pretty simple! There are a few excellent tutorials which get you started real fast. In about half an hour I made this very simple sniffer which accumulates the received bytes and packets per second and prints it out when the second changes. Each line contains the timestamp (sec), KB/s and number of packets received in that second. Here you can see me watching a youtube vid :)

Opening device eth0
ts = 1285276934, load = 0.7 KB/s (4)
ts = 1285276935, load = 0.3 KB/s (1)
ts = 1285276939, load = 0.9 KB/s (4)
ts = 1285276940, load = 14.4 KB/s (44)
ts = 1285276941, load = 294.9 KB/s (764)
ts = 1285276942, load = 608.9 KB/s (1505)
ts = 1285276943, load = 1164.4 KB/s (2882)
ts = 1285276944, load = 1242.6 KB/s (3064)
ts = 1285276945, load = 1166.6 KB/s (2880)
ts = 1285276946, load = 69.9 KB/s (179)
ts = 1285276947, load = 140.1 KB/s (363)
ts = 1285276948, load = 139.9 KB/s (361)
ts = 1285276949, load = 139.7 KB/s (358)
ts = 1285276950, load = 139.7 KB/s (358)
ts = 1285276951, load = 139.3 KB/s (358)
....

It is a good test to see if the calculated payload is correct. The initial burst of ~1.2MB/s confirms that. :)

git through proxy

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You’re at work and want to access your git repo who’s residing in the free external world?

create the following config file in your .ssh folder:

Host
ProxyCommand connect -S <proxy host>:<proxy port> %h %p

replace the hosts and port as appropriate.

You can find the connect executable for windows here (contains a lot of other useful socks info as well).
Hat tip to pieter.