Akom's Tech Ruminations

After using only Linux for nearly 20 years, I'm being forced to use a Windows machine for work. To make matters worse, I'm really (really) used to Enlightenment shortcuts, yet I use XFCE (Xubuntu). So, I'd like to have a seamless experience if I can help it. This is a log of my experimentation.

Note that I am not talking about a skin - I don't care that much about the looks, and I don't need the Windows desktop to look like Mint or Unity. What I want is for Windows to respond with the same level of fluidity that I get from Linux

Continue reading "Customizing Windows 7 keyboard and mouse to act like Linux"

This turned out to be harder than I thought. I found a large (50MB) PDF with about 50 pages, and none of the tesseract GUI's seemed to be able to handle it without crashing. The solution is to convert the PDF to TIFF so that command-line tesseract could handle it directly, but now ImageMagick couldn't handle that conversion as it was running out of memory (even with the limit settings). So the only option was to reduce the load on all the moving parts by splitting the PDF into pages.

Even after splitting the PDF and running each page through the PDF->TIFF->Tesseract->PDF chain I was still having issues:

Error in pixReadFromTiffStream: spp not in set {1,3,4}

Huh? So it turns out that sometimes you may wind up with an alpha channel in your TIFF and tesseract can't handle this. There is a solution, fortunately. So finally, I put all of these steps together into a script:

Continue reading "OCR on a large PDF using tesseract and pdftk"

This turned out to be fairly simple, with only one gotcha: do not follow the how-to's out there that tell you to use expect fork. The process doesn't technically fork. When I had that setting enabled, upstart commands would hang under very specific but repeatable conditions (if the process was killed externally).

So, here is my upstart conf file:

Continue reading "Running Jenkins Swarm client as a service via Upstart"

Why Because my Jenkins setup sometimes starts containers and forgets about them. Either it thinks it failed to start one, or the container itself has trouble starting. Either way, I'm left with containers that are running, trying to connect to Jenkins in vain, forever. The proper way to fix this is probably to have the containers timeout at some point, but that mechanism is broken.

Anyway, the fix I have is a true hack: find containers that have been up more than 2 days and kill them. None of our jobs should run for more than about a day, so this is a safe limit. Here is a bash script to do this:

Continue reading "Docker: Automatically remove containers that have been running too long"

Disclaimer: It is perfectly legal to program an odometer to represent the correct mileage for the car.

Problem:

The car is a 2006 Nissan Sentra 1.8S. The instrument cluster is faulty and flips overdrive on and off at random. I ruled out the rest (switch, TCM). Thus, the cheapest option is to swap in another cluster, but that means that my mileage will be wrong. The replacement cluster I picked up on Ebay has 24K miles. Mine has 181K. Slight difference there.

Solution Summary:

Use an EZP2013 IC programmer to read the memory from your old cluster and write that to the new one. Clearly this assumes that you are still in possession of your old cluster and that its EEPROM is intact.

Solution Detail:

Continue reading "Odometer Reprogramming - Nissan Sentra"

After hours of "Why does it work locally but not in Jenkins", this error boils down to StrictHostKeyChecking... In other words, since the job runs as a user on a random slave, and this user most likely doesn't have a known hosts file with an entry for the target system, this fails rather cryptically. You think that the user's keys don't work, but that's not the problem.

The whole setup boils down to :

1. Install ssh-agent plugin
2. Configure credentials with a valid ssh key for your target
3. Enable ssh-agent with that credential entry in your job config
4. Add StrictHostKeyChecking=no to whatever ssh command you are using. Some examples:
   • GIT:

     export GIT_SSH_COMMAND="ssh -oStrictHostKeyChecking=no"

   • SSH:

     ssh -oStrictHostKeyChecking=no ....

I bought this trimmer in 2008 and the NiCd batteries finally died in 2016 - not bad. Still, no reason to trash a working trimmer and contribute to the landfill problem. As it turns out, it's fairly easy to disassemble, and even easier to reassemble. So here are the steps, which probably apply to many similar models.

Continue reading "Replacing batteries in a Philips Norelco T980 Turbo Vacuum Trimmer"

I've had this toothbrush for over a decade, and the batteries finally died. I suppose that's a long time for NiCd cells to last. For the last year or so the toothbrush would not complete the 2 minute cycle but would instead stop sometime earlier. The batteries are clearly still alive but simply don't have enough capacity.

The toothbrush is not designed to be opened (it is waterproof after all). That should not stop us. The safest way of opening the casing that I could think of was cutting it with a PVC rope saw. This makes a relatively quick cut and mostly does not affect anything besides soft plastic. The circuit board was spared. The location of the cuts is important. I had no idea where the batteries would be so I took a guess and cut it in half. Pulling the two parts apart caused fine wires to get ripped out of the charge coil, something that I could have avoided had I just cut around the batteries. The ideal cut would be just tracing around the batteries on the back side, creating a "battery door" shape. The batteries are soldered directly to the circuit board, so they need to be carefully cut away so that extension wires can be soldered on to allow for some wiggle room.

Opening the casing the wrong way

Continue reading "Replacing batteries in a Sonicare Elite toothbrush"

Couldn't find any good solutions out there. I have a Dell Latitutde E6410 running Ubuntu 15.10 (Update: these instructions worked fine on a Precision 7510 running Ubuntu 18.04) with XFCE (no Gnome or KDE). I use a physical docking station that allows me to use two external monitors. Ubuntu doesn't seem to understand that if these external monitors vanish, it should switch to the monitor that remains (built-in LCD), and vice versa, so I have to automate it myself. (Ubuntu 18.04 does in fact notice monitor changes, but insists on arranging the monitors in the wrong order, so this solution is still necessary)

The trick to doing this reliably is finding a udev device you can monitor using udev rules and perform actions when it appears or disappears. This would be a device that is 100% absent when undocked and is 100% present when docked. There is no kernel built-in dock device on these laptops. In order to watch what devices are coming and going, I used the following command (as root):

udevadm -p -u
udevadm monitor # in Ubuntu 18.x

Run that in a terminal, undock/dock and see what it says. You may want to save the output to a file, it's a lot. In my case, there was nothing definitive. There is "drm" device which sounds promising, but there is no good way to tell a "remove" apart from an "add" event. Ultimately, I settled on the numlock event. Why? Because it is specific to my external USB keyboard (Microsoft 4000) that is always plugged into the docking station. The internal laptop keyboard is unlikely to generate that event, and the full-size keyboard always produces one. Here is the relevant remove event:

Continue reading "Ubuntu 18.04: Handling Dell Latitude laptop dock events to reconfigure displays"

currentBuild.@result = hudson.model.Result.UNSTABLE

Alternatively, to mark the build aborted and terminate immediately instead:

throw new InterruptedException()

Continue reading "Marking Jenkins build UNSTABLE from environment inject groovy script"

1. Convert hundreds (in our case) of Maven jobs to regular (freestyle) jobs. There appears to be no simple script to do this, so I wrote one here
2. Use maven toolchains to compile and test with a different JDK. Although converting jobs is a viable option that requires no additional setup, using toolchains may be preferred in some cases. For one thing, Jenkins offers the "Perform Release" button on maven jobs, something that is difficult to emulate in freestyle jobs.

mount -v /mountpoint                                                                                                               
mount.nfs: timeout set for Wed Dec  9 11:09:27 2015
mount.nfs: trying text-based options 'rsize=8192,wsize=8192,intr,hard,addr=X.X.X.X'
mount.nfs: prog 100003, trying vers=3, prot=6
mount.nfs: portmap query retrying: RPC: Program not registered
mount.nfs: prog 100003, trying vers=3, prot=17
mount.nfs: portmap query failed: RPC: Program not registered
mount.nfs: prog 100003, trying vers=2, prot=6
mount.nfs: portmap query retrying: RPC: Program not registered
mount.nfs: prog 100003, trying vers=2, prot=17
mount.nfs: portmap query failed: RPC: Program not registered
mount.nfs: prog 100003, trying vers=2, prot=6
mount.nfs: portmap query retrying: RPC: Program not registered
mount.nfs: prog 100003, trying vers=2, prot=17
mount.nfs: portmap query failed: RPC: Program not registered
mount.nfs: requested NFS version or transport protocol is not supported

  # deletes the whole tree if it exists
  define registry_wipe_tree($key = $title) {
    exec {"Purge registry $key":
      path => ['c:/windows/system32'],
      command => "reg DELETE \"${key}\" /f",
      onlyif => "reg QUERY \"${key}\"",
    }
  }
 

registry_wipe_tree{'HKLM\SOFTWARE\JavaSoft\Java Update':}
registry_wipe_tree{'HKLM\SOFTWARE\Wow6432Node\JavaSoft\Java Update': }