blog/index.html

   1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
   2           "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
   3 <html xmlns="http://www.w3.org/1999/xhtml" dir="ltr">
   4   <head>
   5     <meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
   6     <title>Petter Reinholdtsen</title>
   7     <link rel="stylesheet" type="text/css" media="screen" href="https://people.skolelinux.org/pere/blog/style.css" />
   8     <link rel="stylesheet" type="text/css" media="screen" href="https://people.skolelinux.org/pere/blog/vim.css" />
   9     <link rel="alternate" title="RSS Feed" href="https://people.skolelinux.org/pere/blog/index.rss" type="application/rss+xml" />
  10   </head>
  11   <body>
  12     <div class="title">
  13  <h1>
  14      <a href="https://people.skolelinux.org/pere/blog/">Petter Reinholdtsen</a>
  15
  16  </h1>
  17
  18 </div>
  19
  20
  21
  22     <div class="entry">
  23       <div class="title"><a href="https://people.skolelinux.org/pere/blog/OpenSnitch_available_in_Debian_Sid_and_Bookworm.html">OpenSnitch available in Debian Sid and Bookworm</a></div>
  24       <div class="date">25th February 2023</div>
  25       <div class="body"><p>Thanks to the efforts of the OpenSnitch lead developer Gustavo
  26 Iñiguez Goya allowing me to sponsor the upload,
  27 <a href="https://tracker.debian.org/pkg/opensnitch">the interactive
  28 application firewall OpenSnitch</a> is now available in Debian
  29 Testing, soon to become the next stable release of Debian.</p>
  30
  31 <p>This is a package which set up a network firewall on one or more
  32 machines, which is controlled by a graphical user interface that will
  33 ask the user if a program should be allowed to connect to the local
  34 network or the Internet.  If some background daemon is trying to dial
  35 home, it can be blocked from doing so with a simple mouse click, or by
  36 default simply by not doing anything when the GUI question dialog pop
  37 up.  A list of all programs discovered using the network is provided
  38 in the GUI, giving the user an overview of how the machine(s) programs
  39 use the network.</p>
  40
  41 <p>OpenSnitch was uploaded for NEW processing about a month ago, and I
  42 had little hope of it getting accepted and shaping up in time for the
  43 package freeze, but the Debian ftpmasters proved to be amazingly quick
  44 at checking out the package and it was accepted into the archive about
  45 week after the first upload.  It is now team maintained under the Go
  46 language team umbrella.  A few fixes to the default setup is only in
  47 Sid, and should migrate to Testing/Bookworm in a week.</p>
  48
  49 <p>During testing I ran into an
  50 <a href="https://github.com/evilsocket/opensnitch/issues/813">issue
  51 with Minecraft server broadcasts disappearing</a>, which was quickly
  52 resolved by the developer with a patch and a proposed configuration
  53 change.  I've been told this was caused by the Debian packages default
  54 use if /proc/ information to track down kernel status, instead of the
  55 newer eBPF module that can be used.  The reason is simply that
  56 upstream and I have failed to find a way to build the eBPF modules for
  57 OpenSnitch without a complete configured Linux kernel source tree,
  58 which as far as we can tell is unavailable as a build dependency in
  59 Debian.  We tried unsuccessfully so far to use the kernel-headers
  60 package.  It would be great if someone could provide some clues how to
  61 build eBPF modules on build daemons in Debian, possibly without the full
  62 kernel source.</p>
  63
  64 <p>As usual, if you use Bitcoin and want to show your support of my
  65 activities, please send Bitcoin donations to my address
  66 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
  67 </div>
  68       <div class="tags">
  69
  70
  71         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>.
  72
  73
  74       </div>
  75     </div>
  76     <div class="padding"></div>
  77
  78     <div class="entry">
  79       <div class="title"><a href="https://people.skolelinux.org/pere/blog/Is_the_desktop_recommending_your_program_for_opening_its_files_.html">Is the desktop recommending your program for opening its files?</a></div>
  80       <div class="date">29th January 2023</div>
  81       <div class="body"><p>Linux desktop systems
  82 <a href="https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html">have
  83 standardized</a> how programs present themselves to the desktop
  84 system.  If a package include a .desktop file in
  85 /usr/share/applications/, Gnome, KDE, LXDE, Xfce and the other desktop
  86 environments will pick up the file and use its content to generate the
  87 menu of available programs in the system.  A lesser known fact is that
  88 a package can also explain to the desktop system how to recognize the
  89 files created by the program in question, and use it to open these
  90 files on request, for example via a GUI file browser.</p>
  91
  92 <p>A while back I ran into a package that did not tell the desktop
  93 system how to recognize its files and was not used to open its files
  94 in the file browser and fixed it.  In the process I wrote a simple
  95 debian/tests/ script to ensure the setup keep working.  It might be
  96 useful for other packages too, to ensure any future version of the
  97 package keep handling its own files.</p>
  98
  99 <p>For this to work the file format need a useful MIME type that can
 100 be used to identify the format.  If the file format do not yet have a
 101 MIME type, it should define one and preferably also
 102 <a href="https://www.iana.org/assignments/media-types/media-types.xhtml">register
 103 it with IANA</a> to ensure the MIME type string is reserved.</p>
 104
 105 <p>The script uses the <tt>xdg-mime</tt> program from xdg-utils to
 106 query the database of standardized package information and ensure it
 107 return sensible values.  It also need the location of an example file
 108 for xdg-mime to guess the format of.</p>
 109
 110 <pre>
 111 #!/bin/sh
 112 #
 113 # Author: Petter Reinholdtsen
 114 # License: GPL v2 or later at your choice.
 115 #
 116 # Validate the MIME setup, making sure motor types have
 117 # application/vnd.openmotor+yaml associated with them and is connected
 118 # to the openmotor desktop file.
 119
 120 retval=0
 121
 122 mimetype="application/vnd.openmotor+yaml"
 123 testfile="test/data/real/o3100/motor.ric"
 124 mydesktopfile="openmotor.desktop"
 125
 126 filemime="$(xdg-mime query filetype "$testfile")"
 127
 128 if [ "$mimetype" != "$filemime" ] ; then
 129     retval=1
 130     echo "error: xdg-mime claim motor file MIME type is $filemine, not $mimetype"
 131 else
 132     echo "success: xdg-mime report correct mime type $mimetype for motor file"
 133 fi
 134
 135 desktop=$(xdg-mime query default "$mimetype")
 136
 137 if [ "$mydesktopfile" != "$desktop" ]; then
 138     retval=1
 139     echo "error: xdg-mime claim motor file should be handled by $desktop, not $mydesktopfile"
 140 else
 141     echo "success: xdg-mime agree motor file should be handled by $mydesktopfile"
 142 fi
 143
 144 exit $retval
 145 </pre>
 146
 147 <p>It is a simple way to ensure your users are not very surprised when
 148 they try to open one of your file formats in their file browser.</p>
 149
 150 <p>As usual, if you use Bitcoin and want to show your support of my
 151 activities, please send Bitcoin donations to my address
 152 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 153 </div>
 154       <div class="tags">
 155
 156
 157         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>.
 158
 159
 160       </div>
 161     </div>
 162     <div class="padding"></div>
 163
 164     <div class="entry">
 165       <div class="title"><a href="https://people.skolelinux.org/pere/blog/Opensnitch__the_application_level_interactive_firewall__heading_into_the_Debian_archive.html">Opensnitch, the application level interactive firewall, heading into the Debian archive</a></div>
 166       <div class="date">22nd January 2023</div>
 167       <div class="body"><p>While reading a
 168 <a href="https://sneak.berlin/20230115/macos-scans-your-local-files-now/">blog
 169 post claiming MacOS X recently started scanning local files and
 170 reporting information about them to Apple</a>, even on a machine where
 171 all such callback features had been disabled, I came across a
 172 description of the Little Snitch application for MacOS X.  It seemed
 173 like a very nice tool to have in the tool box, and I decided to see if
 174 something similar was available for Linux.</p>
 175
 176 <p>It did not take long to find
 177 <a href="https://github.com/evilsocket/opensnitch">the OpenSnitch
 178 package</a>, which has been in development since 2017, and now is in
 179 version 1.5.0.  It has had a
 180 <a href="https://bugs.debian.org/909567">request for Debian
 181 packaging</a> since 2018, but no-one completed the job so far.  Just
 182 for fun, I decided to see if I could help, and I was very happy to
 183 discover that
 184 <a href="https://github.com/evilsocket/opensnitch/issues/304">upstream
 185 want a Debian package too</a>.</p>
 186
 187 <p>After struggling a bit with getting the program to run, figuring
 188 out building Go programs (and a little failed detour to look at eBPF
 189 builds too - help needed), I am very happy to report that I am
 190 sponsoring upstream to maintain the package in Debian, and it has
 191 since this morning been waiting in NEW for the ftpmasters to have a
 192 look.  Perhaps it can get into the archive in time for the Bookworm
 193 release?</p>
 194
 195 <p>As usual, if you use Bitcoin and want to show your support of my
 196 activities, please send Bitcoin donations to my address
 197 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 198 </div>
 199       <div class="tags">
 200
 201
 202         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>.
 203
 204
 205       </div>
 206     </div>
 207     <div class="padding"></div>
 208
 209     <div class="entry">
 210       <div class="title"><a href="https://people.skolelinux.org/pere/blog/LinuxCNC_MQTT_publisher_component.html">LinuxCNC MQTT publisher component</a></div>
 211       <div class="date"> 8th January 2023</div>
 212       <div class="body"><p>I watched <a href="https://yewtu.be/watch?v=jmKUV3aNLjk">a 2015
 213 video from Andreas Schiffler</a> the other day, where he set up
 214 <a href="https://linuxcnc.org/">LinuxCNC</a> to send status
 215 information to the MQTT broker IBM Bluemix.  As I also use MQTT for
 216 graphing, it occured to me that a generic MQTT LinuxCNC component
 217 would be useful and I set out to implement it.  Today I got the first
 218 draft limping along and submitted as
 219 <a href="https://github.com/LinuxCNC/linuxcnc/pull/2253">a patch to the
 220 LinuxCNC project</a>.</p>
 221
 222 <p>The simple part was setting up the MQTT publishing code in Python.
 223 I already have set up other parts submitting data to my Mosquito MQTT
 224 broker, so I could reuse that code.  Writing a LinuxCNC component in
 225 Python as new to me, but using existing examples in the code
 226 repository and the extensive documentation, this was fairly straight
 227 forward.  The hardest part was creating a automated test for the
 228 component to ensure it was working.  Testing it in a simulated
 229 LinuxCNC machine proved very useful, as I discovered features I needed
 230 that I had not thought of yet, and adjusted the code quite a bit to
 231 make it easier to test without a operational MQTT broker
 232 available.</p>
 233
 234 <p>The draft is ready and working, but I am unsure which LinuxCNC HAL
 235 pins I should collect and publish by default (in other words, the
 236 default set of information pieces published), and how to get the
 237 machine name from the LinuxCNC INI file.  The latter is a minor
 238 detail, but I expect it would be useful in a setup with several
 239 machines available.  I am hoping for feedback from the experienced
 240 LinuxCNC developers and users, to make the component even better
 241 before it can go into the mainland LinuxCNC code base.</p>
 242
 243 <p>Since I started on the MQTT component, I came across
 244 <a href="https://yewtu.be/watch?v=Bqa2grG0XtA">another video from Kent
 245 VanderVelden</a> where he combine LinuxCNC with a set of screen glasses
 246 controlled by a Raspberry Pi, and it occured to me that it would
 247 be useful for such use cases if LinuxCNC also provided a REST API for
 248 querying its status.  I hope to start on such component once the MQTT
 249 component is working well.</p>
 250
 251 <p>As usual, if you use Bitcoin and want to show your support of my
 252 activities, please send Bitcoin donations to my address
 253 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 254 </div>
 255       <div class="tags">
 256
 257
 258         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="https://people.skolelinux.org/pere/blog/tags/linuxcnc">linuxcnc</a>, <a href="https://people.skolelinux.org/pere/blog/tags/robot">robot</a>.
 259
 260
 261       </div>
 262     </div>
 263     <div class="padding"></div>
 264
 265     <div class="entry">
 266       <div class="title"><a href="https://people.skolelinux.org/pere/blog/ONVIF_IP_camera_management_tool_finally_in_Debian.html">ONVIF IP camera management tool finally in Debian</a></div>
 267       <div class="date">24th December 2022</div>
 268       <div class="body"><p>Merry Christmas to you all.  Here is a small gift to all those with
 269 IP cameras following the <a href="https://www.onvif.org/">ONVIF
 270 specification</a>.  There is finally a nice command line and GUI tool
 271 in Debian to manage ONVIF IP cameras.  After working with upstream for
 272 a few months and sponsoring the upload, I am very happy to report that
 273 the <a href="https://tracker.debian.org/libonvif">libonvif package</a>
 274 entered Debian Sid last night.</p>
 275
 276 <p>The package provide a C library to communicate with such cameras, a
 277 command line tool to locate and update settings of (like password) the
 278 cameras and a GUI tool to configure and control the units as well as
 279 preview the video from the camera.  Libonvif is available on Both
 280 Linux and Windows and the GUI tool uses the Qt library.  The main
 281 competitors are non-free software, while libonvif is GNU GPL licensed.
 282 I am very glad Debian users in the future can control their cameras
 283 using a free software system provided by Debian.  But the ONVIF world
 284 is full of slightly broken firmware, where the cameras pretend to
 285 follow the ONVIF specification but fail to set some configuration
 286 values or refuse to provide video to more than one recipient at the
 287 time, and the onvif project is quite young and might take a while
 288 before it completely work with your camera.  Upstream seem eager to
 289 improve the library, so handling any broken camera might be just <a
 290 href="https://github.com/sr99622/libonvif/">a bug report away</a>.</p>
 291
 292 <p>The package just cleared NEW, and need a new source only upload
 293 before it can enter testing.  This will happen in the next few
 294 days.</p>
 295
 296 <p>As usual, if you use Bitcoin and want to show your support of my
 297 activities, please send Bitcoin donations to my address
 298 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 299 </div>
 300       <div class="tags">
 301
 302
 303         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="https://people.skolelinux.org/pere/blog/tags/multimedia">multimedia</a>, <a href="https://people.skolelinux.org/pere/blog/tags/standard">standard</a>, <a href="https://people.skolelinux.org/pere/blog/tags/surveillance">surveillance</a>.
 304
 305
 306       </div>
 307     </div>
 308     <div class="padding"></div>
 309
 310     <div class="entry">
 311       <div class="title"><a href="https://people.skolelinux.org/pere/blog/Managing_and_using_ONVIF_IP_cameras_with_Linux.html">Managing and using ONVIF IP cameras with Linux</a></div>
 312       <div class="date">19th October 2022</div>
 313       <div class="body"><p>Recently I have been looking at how to control and collect data
 314 from a handful IP cameras using Linux.  I both wanted to change their
 315 settings and to make their imagery available via a free software
 316 service under my control.  Here is a summary of the tools I found.</p>
 317
 318 <p>First I had to identify the cameras and their protocols.  As far as
 319 I could tell, they were using some SOAP looking protocol and their
 320 internal web server seem to only work with Microsoft Internet Explorer
 321 with some proprietary binary plugin, which in these days of course is
 322 a security disaster and also made it impossible for me to use the
 323 camera web interface.  Luckily I discovered that the SOAP looking
 324 protocol is actually following <a href="https://www.onvif.org/">the
 325 ONVIF specification</a>, which seem to be supported by a lot of IP
 326 cameras these days.</p>
 327
 328 <p>Once the protocol was identified, I was able to find what appear to
 329 be the most popular way to configure ONVIF cameras, the free software
 330 Windows tool named
 331 <a href="https://sourceforge.net/projects/onvifdm/">ONVIF Device
 332 Manager</a>.  Lacking any other options at the time, I tried
 333 unsuccessfully to get it running using Wine, but was missing a dotnet
 334 40 library and I found no way around it to run it on Linux.</p>
 335
 336 <p>The next tool I found to configure the cameras were a non-free Linux Qt
 337 client <a href="https://www.lingodigit.com/onvif_nvcdemo.html">ONVIF
 338 Device Tool</a>.  I did not like its terms of use, so did not spend
 339 much time on it.</p>
 340
 341 <p>To collect the video and make it available in a web interface, I
 342 found the Zoneminder tool in Debian.  A recent version was able to
 343 automatically detect and configure ONVIF devices, so I could use it to
 344 set up motion detection in and collection of the camera output.  I had
 345 initial problems getting the ONVIF autodetection to work, as both
 346 Firefox and Chromium <a href="https://bugs.debian.org/1001188">refused
 347 the inter-tab communication</a> being used by the Zoneminder web
 348 pages, but managed to get konqueror to work.  Apparently the "Enhanced
 349 Tracking Protection" in Firefox cause the problem.  I ended up
 350 upgrading to the Bookworm edition of Zoneminder in the process to try
 351 to fix the issue, and believe the problem might be solved now.</p>
 352
 353 <p>In the process I came across the nice Linux GUI tool
 354 <a href="https://gitlab.com/caspermeijn/onvifviewer/">ONVIF Viewer</a>
 355 allowing me to preview the camera output and validate the login
 356 passwords required.  Sadly its author has grown tired of maintaining
 357 the software, so it might not see any future updates.  Which is sad,
 358 as the viewer is sightly unstable and the picture tend to lock up.
 359 Note, this lockup might be due to limitations in the cameras and not
 360 the viewer implementation.  I suspect the camera is only able to
 361 provide pictures to one client at the time, and the Zoneminder feed
 362 might interfere with the GUI viewer.  I have
 363 <a href="https://bugs.debian.org/1000820">asked for the tool to be
 364 included in Debian</a>.</p>
 365
 366 <p>Finally, I found what appear to be very nice Linux free software
 367 replacement for the Windows tool, named
 368 <a href="https://github.com/sr99622/libonvif/">libonvif</a>.  It
 369 provide a C library to talk to ONVIF devices as well as a command line
 370 and GUI tool using the library.  Using the GUI tool I was able to change
 371 the admin passwords and update other settings of the cameras.  I have
 372 <a href="https://bugs.debian.org/1021980">asked for the package to be
 373 included in Debian</a>.</p>
 374
 375 <p>As usual, if you use Bitcoin and want to show your support of my
 376 activities, please send Bitcoin donations to my address
 377 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 378
 379 <p><strong>Update 2022-10-20</strong>: Since my initial publication of
 380 this text, I got several suggestions for more free software Linux
 381 tools.  There is <a href="https://github.com/quatanium/python-onvif">a
 382 ONVIF python library</a> (already
 383 <a href="https://bugs.debian.org/824240">requested into Debian</a>) and
 384 <a href="https://github.com/FalkTannhaeuser/python-onvif-zeep">a python 3
 385 fork</a> using a different SOAP dependency.  There is also
 386 <a href="https://www.home-assistant.io/integrations/onvif/">support for
 387 ONVIF in Home Assistant</a>, and there is an alternative to Zoneminder
 388 called <a href="https://www.shinobi.video/">Shinobi</a>.  The latter
 389 two are not included in Debian either.  I have not tested any of these
 390 so far.</p>
 391 </div>
 392       <div class="tags">
 393
 394
 395         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="https://people.skolelinux.org/pere/blog/tags/multimedia">multimedia</a>, <a href="https://people.skolelinux.org/pere/blog/tags/standard">standard</a>, <a href="https://people.skolelinux.org/pere/blog/tags/surveillance">surveillance</a>.
 396
 397
 398       </div>
 399     </div>
 400     <div class="padding"></div>
 401
 402     <div class="entry">
 403       <div class="title"><a href="https://people.skolelinux.org/pere/blog/Time_to_translate_the_Bullseye_edition_of_the_Debian_Administrator_s_Handbook.html">Time to translate the Bullseye edition of the Debian Administrator's Handbook</a></div>
 404       <div class="date">12th September 2022</div>
 405       <div class="body"><p align="center"><img align="center" src="http://people.skolelinux.org/pere/blog/images/2020-10-20-debian-handbook-nb-testprint.jpeg" width="60%"/></p>
 406
 407 <p>(The picture is of the previous edition.)</p>
 408
 409 <p>Almost two years after the previous Norwegian Bokmål translation of
 410 the "<a href="https://debian-handbook.info/">The Debian Administrator's
 411 Handbook</a>" was published, a new edition is finally being prepared.  The
 412 english text is updated, and it is time to start working on the
 413 translations.  Around 37 percent of the strings have been updated, one
 414 way or another, and the translations starting from a complete Debian Buster
 415 edition now need to bring their translation up from 63% to 100%.  The
 416 complete book is licensed using a Creative Commons license, and has
 417 been published in several languages over the years.  The translations
 418 are done by volunteers to bring Linux in their native tongue.  The
 419 last time I checked, it complete text was available in English,
 420 Norwegian Bokmål, German, Indonesian, Brazil Portuguese and Spanish.
 421 In addition, work has been started for Arabic (Morocco), Catalan,
 422 Chinese (Simplified), Chinese (Traditional), Croatian, Czech, Danish,
 423 Dutch, French, Greek, Italian, Japanese, Korean, Persian, Polish,
 424 Romanian, Russian, Swedish, Turkish and Vietnamese.</p>
 425
 426 <p>The translation is conducted on
 427 <a href="https://hosted.weblate.org/projects/debian-handbook/">the
 428 hosted weblate project page</a>.  Prospective translators are
 429 recommeded to subscribe to
 430 <a href="http://lists.alioth.debian.org/mailman/listinfo/debian-handbook-translators">the
 431 translators mailing list</a> and should also check out
 432 <a href="https://debian-handbook.info/contribute/">the instructions for
 433 contributors</a>.</p>
 434
 435 <p>I am one of the Norwegian Bokmål translators of this book, and we
 436 have just started.  Your contribution is most welcome.</p>
 437
 438 <p>As usual, if you use Bitcoin and want to show your support of my
 439 activities, please send Bitcoin donations to my address
 440 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 441 </div>
 442       <div class="tags">
 443
 444
 445         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/debian-handbook">debian-handbook</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>.
 446
 447
 448       </div>
 449     </div>
 450     <div class="padding"></div>
 451
 452     <div class="entry">
 453       <div class="title"><a href="https://people.skolelinux.org/pere/blog/Automatic_LinuxCNC_servo_PID_tuning_.html">Automatic LinuxCNC servo PID tuning?</a></div>
 454       <div class="date">16th July 2022</div>
 455       <div class="body"><p>While working on a CNC with servo motors controlled by the
 456 <a href="https://en.wikipedia.org/wiki/LinuxCNC">LinuxCNC</a>
 457 <a href="https://en.wikipedia.org/wiki/PID_controller">PID
 458 controller</a>, I recently had to learn how to tune the collection of values
 459 that control such mathematical machinery that a PID controller is.  It
 460 proved to be a lot harder than I hoped, and I still have not succeeded
 461 in getting the Z PID controller to successfully defy gravity, nor X
 462 and Y to move accurately and reliably.  But while climbing up this
 463 rather steep learning curve, I discovered that some motor control
 464 systems are able to tune their PID controllers.  I got the impression
 465 from the documentation that LinuxCNC were not.  This proved to be not
 466 true.</p>
 467
 468 <p>The LinuxCNC
 469 <a href="http://linuxcnc.org/docs/html/man/man9/pid.9.html">pid
 470 component</a> is the recommended PID controller to use.  It uses eight
 471 constants <tt>Pgain</tt>, <tt>Igain</tt>, <tt>Dgain</tt>,
 472 <tt>bias</tt>, <tt>FF0</tt>, <tt>FF1</tt>, <tt>FF2</tt> and
 473 <tt>FF3</tt> to calculate the output value based on current and wanted
 474 state, and all of these need to have a sensible value for the
 475 controller to behave properly.  Note, there are even more values
 476 involved, theser are just the most important ones.  In my case I need
 477 the X, Y and Z axes to follow the requested path with little error.
 478 This has proved quite a challenge for someone who have never tuned a
 479 PID controller before, but there is at least some help to be found.
 480
 481 <p>I discovered that included in LinuxCNC was this old PID component
 482 at_pid claiming to have auto tuning capabilities.  Sadly it had been
 483 neglected since 2011, and could not be used as a plug in replacement
 484 for the default pid component.  One would have to rewriting the
 485 LinuxCNC HAL setup to test at_pid.  This was rather sad, when I wanted
 486 to quickly test auto tuning to see if it did a better job than me at
 487 figuring out good P, I and D values to use.</p>
 488
 489 <p>I decided to have a look if the situation could be improved.  This
 490 involved trying to understand the code and history of the pid and
 491 at_pid components.  Apparently they had a common ancestor, as code
 492 structure, comments and variable names were quite close to each other.
 493 Sadly this was not reflected in the git history, making it hard to
 494 figure out what really happened.  My guess is that the author of
 495 <a href="https://github.com/LinuxCNC/linuxcnc/blob/master/src/hal/components/at_pid.c">at_pid.c</a>
 496 took a version of
 497 <a href="https://github.com/LinuxCNC/linuxcnc/blob/master/src/hal/components/pid.c">pid.c</a>,
 498 rewrote it to follow the structure he wished pid.c to have, then added
 499 support for auto tuning and finally got it included into the LinuxCNC
 500 repository.  The restructuring and lack of early history made it
 501 harder to figure out which part of the code were relevant to the auto
 502 tuning, and which part of the code needed to be updated to work the
 503 same way as the current pid.c implementation.  I started by trying to
 504 isolate relevant changes in pid.c, and applying them to at_pid.c.  My
 505 aim was to make sure the at_pid component could replace the pid
 506 component with a simple change in the HAL setup loadrt line, without
 507 having to "rewire" the rest of the HAL configuration.  After a few
 508 hours following this approach, I had learned quite a lot about the
 509 code structure of both components, while concluding I was heading down
 510 the wrong rabbit hole, and should get back to the surface and find a
 511 different path.</p>
 512
 513 <p>For the second attempt, I decided to throw away all the PID control
 514 related part of the original at_pid.c, and instead isolate and lift
 515 the auto tuning part of the code and inject it into a copy of pid.c.
 516 This ensured compatibility with the current pid component, while
 517 adding auto tuning as a run time option.  To make it easier to identify
 518 the relevant parts in the future, I wrapped all the auto tuning code
 519 with '#ifdef AUTO_TUNER'.  The end result behave just like the current
 520 pid component by default, as that part of the code is identical.  The
 521 <a href="https://github.com/LinuxCNC/linuxcnc/pull/1820">end result
 522 entered the LinuxCNC master branch</a> a few days ago.</p>
 523
 524 <p>To enable auto tuning, one need to set a few HAL pins in the PID
 525 component.  The most important ones are <tt>tune-effort</tt>,
 526 <tt>tune-mode</tt> and <tt>tune-start</tt>.  But lets take a step
 527 back, and see what the auto tuning code will do.  I do not know the
 528 mathematical foundation of the at_pid algorithm, but from observation
 529 I can tell that the algorithm will, when enabled, produce a square
 530 wave pattern centered around the <tt>bias</tt> value on the output pin
 531 of the PID controller.  This can be seen using the HAL Scope provided
 532 by LinuxCNC.  In my case, this is translated into voltage (+-10V) sent
 533 to the motor controller, which in turn is translated into motor speed.
 534 So at_pid will ask the motor to move the axis back and forth.  The
 535 number of cycles in the pattern is controlled by the
 536 <tt>tune-cycles</tt> pin, and the extremes of the wave pattern is
 537 controlled by the <tt>tune-effort</tt> pin.  Of course, trying to
 538 change the direction of a physical object instantly (as in going
 539 directly from a positive voltage to the equivalent negative voltage)
 540 do not change velocity instantly, and it take some time for the object
 541 to slow down and move in the opposite direction.  This result in a
 542 more smooth movement wave form, as the axis in question were vibrating
 543 back and forth.  When the axis reached the target speed in the
 544 opposing direction, the auto tuner change direction again.  After
 545 several of these changes, the average time delay between the 'peaks'
 546 and 'valleys' of this movement graph is then used to calculate
 547 proposed values for Pgain, Igain and Dgain, and insert them into the
 548 HAL model to use by the pid controller.  The auto tuned settings are
 549 not great, but htye work a lot better than the values I had been able
 550 to cook up on my own, at least for the horizontal X and Y axis.  But I
 551 had to use very small <tt>tune-effort<tt> values, as my motor
 552 controllers error out if the voltage change too quickly.  I've been
 553 less lucky with the Z axis, which is moving a heavy object up and
 554 down, and seem to confuse the algorithm.  The Z axis movement became a
 555 lot better when I introduced a <tt>bias</tt> value to counter the
 556 gravitational drag, but I will have to work a lot more on the Z axis
 557 PID values.</p>
 558
 559 <p>Armed with this knowledge, it is time to look at how to do the
 560 tuning.  Lets say the HAL configuration in question load the PID
 561 component for X, Y and Z like this:</p>
 562
 563 <blockquote><pre>
 564 loadrt pid names=pid.x,pid.y,pid.z
 565 </pre></blockquote>
 566
 567 <p>Armed with the new and improved at_pid component, the new line will
 568 look like this:</p>
 569
 570 <blockquote><pre>
 571 loadrt at_pid names=pid.x,pid.y,pid.z
 572 </pre></blockquote>
 573
 574 <p>The rest of the HAL setup can stay the same.  This work because the
 575 components are referenced by name.  If the component had used count=3
 576 instead, all use of pid.# had to be changed to at_pid.#.</p>
 577
 578 <p>To start tuning the X axis, move the axis to the middle of its
 579 range, to make sure it do not hit anything when it start moving back
 580 and forth.  Next, set the <tt>tune-effort</tt> to a low number in the
 581 output range.  I used 0.1 as my initial value.  Next, assign 1 to the
 582 <tt>tune-mode</tt> value. Note, this will disable the pid controlling
 583 part and feed 0 to the output pin, which in my case initially caused a
 584 lot of drift.  In my case it proved to be a good idea with X and Y to
 585 tune the motor driver to make sure 0 voltage stopped the motor
 586 rotation.  On the other hand, for the Z axis this proved to be a bad
 587 idea, so it will depend on your setup.  It might help to set the
 588 <tt>bias</tt> value to a output value that reduce or eliminate the
 589 axis drift.  Finally, after setting <tt>tune-mode</tt>, set
 590 <tt>tune-start</tt> to 1 to activate the auto tuning.  If all go well,
 591 your axis will vibrate for a few seconds and when it is done, new
 592 values for Pgain, Igain and Dgain will be active.  To test them,
 593 change <tt>tune-mode</tt> back to 0.  Note that this might cause the
 594 machine to suddenly jerk as it bring the axis back to its commanded
 595 position, which it might have drifted away from during tuning.  To
 596 summarize with some halcmd lines:</p>
 597
 598 <blockquote><pre>
 599 setp pid.x.tune-effort 0.1
 600 setp pid.x.tune-mode 1
 601 setp pid.x.tune-start 1
 602 # wait for the tuning to complete
 603 setp pid.x.tune-mode 0
 604 </pre></blockquote>
 605
 606 <p>After doing this task quite a few times while trying to figure out
 607 how to properly tune the PID controllers on the machine in, I decided
 608 to figure out if this process could be automated, and wrote a script
 609 to do the entire tuning process from power on.  The end result will
 610 ensure the machine is powered on and ready to run, home all axis if it
 611 is not already done, check that the extra tuning pins are available,
 612 move the axis to its mid point, run the auto tuning and re-enable the
 613 pid controller when it is done.  It can be run several times.  Check
 614 out the
 615 <a href="https://github.com/SebKuzminsky/MazakVQC1540/blob/bon-dev/scripts/run-auto-pid-tuner">run-auto-pid-tuner</a>
 616 script on github if you want to learn how it is done.</p>
 617
 618 <p>My hope is that this little adventure can inspire someone who know
 619 more about motor PID controller tuning can implement even better
 620 algorithms for automatic PID tuning in LinuxCNC, making life easier
 621 for both me and all the others that want to use LinuxCNC but lack the
 622 in depth knowledge needed to tune PID controllers well.</p>
 623
 624 <p>As usual, if you use Bitcoin and want to show your support of my
 625 activities, please send Bitcoin donations to my address
 626 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 627 </div>
 628       <div class="tags">
 629
 630
 631         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/3d-printer">3d-printer</a>, <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="https://people.skolelinux.org/pere/blog/tags/linuxcnc">linuxcnc</a>, <a href="https://people.skolelinux.org/pere/blog/tags/robot">robot</a>.
 632
 633
 634       </div>
 635     </div>
 636     <div class="padding"></div>
 637
 638     <div class="entry">
 639       <div class="title"><a href="https://people.skolelinux.org/pere/blog/My_free_software_activity_of_late__2022_.html">My free software activity of late (2022)</a></div>
 640       <div class="date">20th June 2022</div>
 641       <div class="body"><p>I guess it is time to bring some light on the various free software
 642 and open culture activities and projects I have worked on or been
 643 involved in the last year and a half.</p>
 644
 645 <p>First, lets mention the book
 646 <a href="http://www.hungry.com/~pere/publisher/">releases I managed to
 647 publish</a>.  The Cory Doctorow book "Hvordan knuse
 648 overvåkningskapitalismen" argue that it is not the magic machine
 649 learning of the big technology companies that causes the surveillance
 650 capitalism to thrive, it is the lack of trust busting to enforce
 651 existing anti-monopoly laws.  I also published a family of
 652 dictionaries for machinists, one sorted on the English words, one
 653 sorted on the Norwegian and the last sorted on the North Sámi words.
 654 A bit on the back burner but not forgotten is the Debian
 655 Administrators Handbook, where a new edition is being worked on.  I
 656 have not spent as much time as I want to help bring it to completion,
 657 but hope I will get more spare time to look at it before the end of
 658 the year.</p>
 659
 660 <p>With my Debian had I have spent time on several projects, both
 661 updating existing packages, helping to bring in new packages and
 662 working with upstream projects to try to get them ready to go into
 663 Debian.  The list is rather long, and I will only mention my own
 664 isenkram, openmotor, vlc bittorrent plugin, xprintidle, norwegian
 665 letter style for latex, bs1770gain, and recordmydesktop.  In addition
 666 to these I have sponsored several packages into Debian, like audmes.</p>
 667
 668 <p>The last year I have looked at several infrastructure projects for
 669 collecting meter data and video surveillance recordings.  This include
 670 several ONVIF related tools like onvifviewer and zoneminder as well as
 671 rtl-433, wmbusmeters and rtl-wmbus.</p>
 672
 673 <p>In parallel with this I have looked at fabrication related free
 674 software solutions like pycam and LinuxCNC.  The latter recently
 675 gained improved translation support using po4a and weblate, which was
 676 a harder nut to crack that I had anticipated when I started.</p>
 677
 678 <p>Several hours have been spent translating free software to
 679 Norwegian Bokmål on the Weblate hosted service.  Do not have a
 680 complete list, but you will find my contributions in at least gnucash,
 681 minetest and po4a.</p>
 682
 683 <p>I also spent quite some time on the Norwegian archiving specification
 684 Noark 5, and its companion project Nikita implementing the API
 685 specification for Noark 5.</p>
 686
 687 <p>Recently I have been looking into free software tools to do company
 688 accounting here in Norway., which present an interesting mix between
 689 law, rules, regulations, format specifications and API interfaces.</p>
 690
 691 <p>I guess I should also mention the Norwegian community driven
 692 government interfacing projects Mimes Brønn and Fiksgatami, which have
 693 ended up in a kind of limbo while the future of the projects is being
 694 worked out.</p>
 695
 696 <p>These are just a few of the projects I have been involved it, and
 697 would like to give more visibility.  I'll stop here to avoid delaying
 698 this post.</p>
 699
 700 <p>As usual, if you use Bitcoin and want to show your support of my
 701 activities, please send Bitcoin donations to my address
 702 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 703 </div>
 704       <div class="tags">
 705
 706
 707         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>.
 708
 709
 710       </div>
 711     </div>
 712     <div class="padding"></div>
 713
 714     <div class="entry">
 715       <div class="title"><a href="https://people.skolelinux.org/pere/blog/LinuxCNC_translators_life_just_got_a_bit_easier.html">LinuxCNC translators life just got a bit easier</a></div>
 716       <div class="date"> 3rd June 2022</div>
 717       <div class="body"><p>Back in oktober last year, when I started looking at the
 718 <a href="https://en.wikipedia.org/wiki/LinuxCNC">LinuxCNC</a> system, I
 719 proposed to change the documentation build system make life easier for
 720 translators.  The original system consisted of independently written
 721 documentation files for each language, with no automated way to track
 722 changes done in other translations and no help for the translators to
 723 know how much was left to translated.  By using
 724 <a href="https://po4a.org/">the po4a system</a> to generate POT and PO
 725 files from the English documentation, this can be improved.  A small
 726 team of LinuxCNC contributors got together and today our labour
 727 finally payed off.  Since a few hours ago, it is now possible to
 728 translate <a href="https://hosted.weblate.org/projects/linuxcnc/">the
 729 LinuxCNC documentation on Weblate</a>, alongside the program itself.</p>
 730
 731 <p>The effort to migrate the documentation to use po4a has been both
 732 slow and frustrating.  I am very happy we finally made it.</p>
 733
 734 <p>As usual, if you use Bitcoin and want to show your support of my
 735 activities, please send Bitcoin donations to my address
 736 <b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
 737 </div>
 738       <div class="tags">
 739
 740
 741         Tags: <a href="https://people.skolelinux.org/pere/blog/tags/3d-printer">3d-printer</a>, <a href="https://people.skolelinux.org/pere/blog/tags/debian">debian</a>, <a href="https://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="https://people.skolelinux.org/pere/blog/tags/linuxcnc">linuxcnc</a>, <a href="https://people.skolelinux.org/pere/blog/tags/robot">robot</a>.
 742
 743
 744       </div>
 745     </div>
 746     <div class="padding"></div>
 747
 748     <p style="text-align: right;"><a href="index.rss"><img src="https://people.skolelinux.org/pere/blog/xml.gif" alt="RSS feed" width="36" height="14" /></a></p>
 749     <div id="sidebar">
 750
 751
 752
 753 <h2>Archive</h2>
 754 <ul>
 755
 756 <li>2023
 757 <ul>
 758
 759 <li><a href="https://people.skolelinux.org/pere/blog/archive/2023/01/">January (3)</a></li>
 760
 761 <li><a href="https://people.skolelinux.org/pere/blog/archive/2023/02/">February (1)</a></li>
 762
 763 </ul></li>
 764
 765 <li>2022
 766 <ul>
 767
 768 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/02/">February (1)</a></li>
 769
 770 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/03/">March (3)</a></li>
 771
 772 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/04/">April (2)</a></li>
 773
 774 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/06/">June (2)</a></li>
 775
 776 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/07/">July (1)</a></li>
 777
 778 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/09/">September (1)</a></li>
 779
 780 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/10/">October (1)</a></li>
 781
 782 <li><a href="https://people.skolelinux.org/pere/blog/archive/2022/12/">December (1)</a></li>
 783
 784 </ul></li>
 785
 786 <li>2021
 787 <ul>
 788
 789 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/01/">January (2)</a></li>
 790
 791 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/02/">February (1)</a></li>
 792
 793 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/05/">May (1)</a></li>
 794
 795 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/06/">June (1)</a></li>
 796
 797 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/07/">July (3)</a></li>
 798
 799 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/08/">August (1)</a></li>
 800
 801 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/09/">September (1)</a></li>
 802
 803 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/10/">October (1)</a></li>
 804
 805 <li><a href="https://people.skolelinux.org/pere/blog/archive/2021/12/">December (1)</a></li>
 806
 807 </ul></li>
 808
 809 <li>2020
 810 <ul>
 811
 812 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/02/">February (2)</a></li>
 813
 814 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/03/">March (2)</a></li>
 815
 816 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/04/">April (2)</a></li>
 817
 818 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/05/">May (3)</a></li>
 819
 820 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/06/">June (2)</a></li>
 821
 822 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/07/">July (1)</a></li>
 823
 824 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/09/">September (1)</a></li>
 825
 826 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/10/">October (1)</a></li>
 827
 828 <li><a href="https://people.skolelinux.org/pere/blog/archive/2020/11/">November (1)</a></li>
 829
 830 </ul></li>
 831
 832 <li>2019
 833 <ul>
 834
 835 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/01/">January (4)</a></li>
 836
 837 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/02/">February (3)</a></li>
 838
 839 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/03/">March (3)</a></li>
 840
 841 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/05/">May (2)</a></li>
 842
 843 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/06/">June (5)</a></li>
 844
 845 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/07/">July (2)</a></li>
 846
 847 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/08/">August (1)</a></li>
 848
 849 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/09/">September (1)</a></li>
 850
 851 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/11/">November (1)</a></li>
 852
 853 <li><a href="https://people.skolelinux.org/pere/blog/archive/2019/12/">December (4)</a></li>
 854
 855 </ul></li>
 856
 857 <li>2018
 858 <ul>
 859
 860 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/01/">January (1)</a></li>
 861
 862 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/02/">February (5)</a></li>
 863
 864 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/03/">March (5)</a></li>
 865
 866 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/04/">April (3)</a></li>
 867
 868 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/06/">June (2)</a></li>
 869
 870 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/07/">July (5)</a></li>
 871
 872 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/08/">August (3)</a></li>
 873
 874 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/09/">September (3)</a></li>
 875
 876 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/10/">October (5)</a></li>
 877
 878 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/11/">November (2)</a></li>
 879
 880 <li><a href="https://people.skolelinux.org/pere/blog/archive/2018/12/">December (4)</a></li>
 881
 882 </ul></li>
 883
 884 <li>2017
 885 <ul>
 886
 887 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/01/">January (4)</a></li>
 888
 889 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/02/">February (3)</a></li>
 890
 891 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/03/">March (5)</a></li>
 892
 893 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/04/">April (2)</a></li>
 894
 895 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/06/">June (5)</a></li>
 896
 897 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/07/">July (1)</a></li>
 898
 899 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/08/">August (1)</a></li>
 900
 901 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/09/">September (3)</a></li>
 902
 903 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/10/">October (5)</a></li>
 904
 905 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/11/">November (3)</a></li>
 906
 907 <li><a href="https://people.skolelinux.org/pere/blog/archive/2017/12/">December (4)</a></li>
 908
 909 </ul></li>
 910
 911 <li>2016
 912 <ul>
 913
 914 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/01/">January (3)</a></li>
 915
 916 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/02/">February (2)</a></li>
 917
 918 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/03/">March (3)</a></li>
 919
 920 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/04/">April (8)</a></li>
 921
 922 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/05/">May (8)</a></li>
 923
 924 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/06/">June (2)</a></li>
 925
 926 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/07/">July (2)</a></li>
 927
 928 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/08/">August (5)</a></li>
 929
 930 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/09/">September (2)</a></li>
 931
 932 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/10/">October (3)</a></li>
 933
 934 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/11/">November (8)</a></li>
 935
 936 <li><a href="https://people.skolelinux.org/pere/blog/archive/2016/12/">December (5)</a></li>
 937
 938 </ul></li>
 939
 940 <li>2015
 941 <ul>
 942
 943 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/01/">January (7)</a></li>
 944
 945 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/02/">February (6)</a></li>
 946
 947 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/03/">March (1)</a></li>
 948
 949 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/04/">April (4)</a></li>
 950
 951 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/05/">May (3)</a></li>
 952
 953 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/06/">June (4)</a></li>
 954
 955 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/07/">July (6)</a></li>
 956
 957 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/08/">August (2)</a></li>
 958
 959 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/09/">September (2)</a></li>
 960
 961 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/10/">October (9)</a></li>
 962
 963 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/11/">November (6)</a></li>
 964
 965 <li><a href="https://people.skolelinux.org/pere/blog/archive/2015/12/">December (3)</a></li>
 966
 967 </ul></li>
 968
 969 <li>2014
 970 <ul>
 971
 972 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/01/">January (2)</a></li>
 973
 974 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/02/">February (3)</a></li>
 975
 976 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/03/">March (8)</a></li>
 977
 978 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/04/">April (7)</a></li>
 979
 980 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/05/">May (1)</a></li>
 981
 982 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/06/">June (2)</a></li>
 983
 984 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/07/">July (2)</a></li>
 985
 986 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/08/">August (2)</a></li>
 987
 988 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/09/">September (5)</a></li>
 989
 990 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/10/">October (6)</a></li>
 991
 992 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/11/">November (3)</a></li>
 993
 994 <li><a href="https://people.skolelinux.org/pere/blog/archive/2014/12/">December (5)</a></li>
 995
 996 </ul></li>
 997
 998 <li>2013
 999 <ul>
1000
1001 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/01/">January (11)</a></li>
1002
1003 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/02/">February (9)</a></li>
1004
1005 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/03/">March (9)</a></li>
1006
1007 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/04/">April (6)</a></li>
1008
1009 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/05/">May (9)</a></li>
1010
1011 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/06/">June (10)</a></li>
1012
1013 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/07/">July (7)</a></li>
1014
1015 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/08/">August (3)</a></li>
1016
1017 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/09/">September (5)</a></li>
1018
1019 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/10/">October (7)</a></li>
1020
1021 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/11/">November (9)</a></li>
1022
1023 <li><a href="https://people.skolelinux.org/pere/blog/archive/2013/12/">December (3)</a></li>
1024
1025 </ul></li>
1026
1027 <li>2012
1028 <ul>
1029
1030 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/01/">January (7)</a></li>
1031
1032 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/02/">February (10)</a></li>
1033
1034 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/03/">March (17)</a></li>
1035
1036 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/04/">April (12)</a></li>
1037
1038 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/05/">May (12)</a></li>
1039
1040 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/06/">June (20)</a></li>
1041
1042 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/07/">July (17)</a></li>
1043
1044 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/08/">August (6)</a></li>
1045
1046 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/09/">September (9)</a></li>
1047
1048 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/10/">October (17)</a></li>
1049
1050 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/11/">November (10)</a></li>
1051
1052 <li><a href="https://people.skolelinux.org/pere/blog/archive/2012/12/">December (7)</a></li>
1053
1054 </ul></li>
1055
1056 <li>2011
1057 <ul>
1058
1059 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/01/">January (16)</a></li>
1060
1061 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/02/">February (6)</a></li>
1062
1063 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/03/">March (6)</a></li>
1064
1065 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/04/">April (7)</a></li>
1066
1067 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/05/">May (3)</a></li>
1068
1069 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/06/">June (2)</a></li>
1070
1071 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/07/">July (7)</a></li>
1072
1073 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/08/">August (6)</a></li>
1074
1075 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/09/">September (4)</a></li>
1076
1077 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/10/">October (2)</a></li>
1078
1079 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/11/">November (3)</a></li>
1080
1081 <li><a href="https://people.skolelinux.org/pere/blog/archive/2011/12/">December (1)</a></li>
1082
1083 </ul></li>
1084
1085 <li>2010
1086 <ul>
1087
1088 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/01/">January (2)</a></li>
1089
1090 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/02/">February (1)</a></li>
1091
1092 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/03/">March (3)</a></li>
1093
1094 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/04/">April (3)</a></li>
1095
1096 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/05/">May (9)</a></li>
1097
1098 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/06/">June (14)</a></li>
1099
1100 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/07/">July (12)</a></li>
1101
1102 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/08/">August (13)</a></li>
1103
1104 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/09/">September (7)</a></li>
1105
1106 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/10/">October (9)</a></li>
1107
1108 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/11/">November (13)</a></li>
1109
1110 <li><a href="https://people.skolelinux.org/pere/blog/archive/2010/12/">December (12)</a></li>
1111
1112 </ul></li>
1113
1114 <li>2009
1115 <ul>
1116
1117 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/01/">January (8)</a></li>
1118
1119 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/02/">February (8)</a></li>
1120
1121 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/03/">March (12)</a></li>
1122
1123 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/04/">April (10)</a></li>
1124
1125 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/05/">May (9)</a></li>
1126
1127 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/06/">June (3)</a></li>
1128
1129 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/07/">July (4)</a></li>
1130
1131 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/08/">August (3)</a></li>
1132
1133 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/09/">September (1)</a></li>
1134
1135 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/10/">October (2)</a></li>
1136
1137 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/11/">November (3)</a></li>
1138
1139 <li><a href="https://people.skolelinux.org/pere/blog/archive/2009/12/">December (3)</a></li>
1140
1141 </ul></li>
1142
1143 <li>2008
1144 <ul>
1145
1146 <li><a href="https://people.skolelinux.org/pere/blog/archive/2008/11/">November (5)</a></li>
1147
1148 <li><a href="https://people.skolelinux.org/pere/blog/archive/2008/12/">December (7)</a></li>
1149
1150 </ul></li>
1151
1152 </ul>
1153
1154
1155
1156 <h2>Tags</h2>
1157 <ul>
1158
1159  <li><a href="https://people.skolelinux.org/pere/blog/tags/3d-printer">3d-printer (19)</a></li>
1160
1161  <li><a href="https://people.skolelinux.org/pere/blog/tags/amiga">amiga (1)</a></li>
1162
1163  <li><a href="https://people.skolelinux.org/pere/blog/tags/aros">aros (1)</a></li>
1164
1165  <li><a href="https://people.skolelinux.org/pere/blog/tags/bankid">bankid (4)</a></li>
1166
1167  <li><a href="https://people.skolelinux.org/pere/blog/tags/betalkontant">betalkontant (9)</a></li>
1168
1169  <li><a href="https://people.skolelinux.org/pere/blog/tags/bitcoin">bitcoin (12)</a></li>
1170
1171  <li><a href="https://people.skolelinux.org/pere/blog/tags/bootsystem">bootsystem (17)</a></li>
1172
1173  <li><a href="https://people.skolelinux.org/pere/blog/tags/bsa">bsa (2)</a></li>
1174
1175  <li><a href="https://people.skolelinux.org/pere/blog/tags/chrpath">chrpath (2)</a></li>
1176
1177  <li><a href="https://people.skolelinux.org/pere/blog/tags/debian">debian (188)</a></li>
1178
1179  <li><a href="https://people.skolelinux.org/pere/blog/tags/debian edu">debian edu (159)</a></li>
1180
1181  <li><a href="https://people.skolelinux.org/pere/blog/tags/debian-handbook">debian-handbook (9)</a></li>
1182
1183  <li><a href="https://people.skolelinux.org/pere/blog/tags/digistan">digistan (11)</a></li>
1184
1185  <li><a href="https://people.skolelinux.org/pere/blog/tags/dld">dld (18)</a></li>
1186
1187  <li><a href="https://people.skolelinux.org/pere/blog/tags/docbook">docbook (30)</a></li>
1188
1189  <li><a href="https://people.skolelinux.org/pere/blog/tags/drivstoffpriser">drivstoffpriser (4)</a></li>
1190
1191  <li><a href="https://people.skolelinux.org/pere/blog/tags/english">english (444)</a></li>
1192
1193  <li><a href="https://people.skolelinux.org/pere/blog/tags/fiksgatami">fiksgatami (23)</a></li>
1194
1195  <li><a href="https://people.skolelinux.org/pere/blog/tags/fildeling">fildeling (14)</a></li>
1196
1197  <li><a href="https://people.skolelinux.org/pere/blog/tags/freeculture">freeculture (34)</a></li>
1198
1199  <li><a href="https://people.skolelinux.org/pere/blog/tags/freedombox">freedombox (9)</a></li>
1200
1201  <li><a href="https://people.skolelinux.org/pere/blog/tags/frikanalen">frikanalen (20)</a></li>
1202
1203  <li><a href="https://people.skolelinux.org/pere/blog/tags/h264">h264 (20)</a></li>
1204
1205  <li><a href="https://people.skolelinux.org/pere/blog/tags/intervju">intervju (43)</a></li>
1206
1207  <li><a href="https://people.skolelinux.org/pere/blog/tags/isenkram">isenkram (16)</a></li>
1208
1209  <li><a href="https://people.skolelinux.org/pere/blog/tags/kart">kart (23)</a></li>
1210
1211  <li><a href="https://people.skolelinux.org/pere/blog/tags/kodi">kodi (4)</a></li>
1212
1213  <li><a href="https://people.skolelinux.org/pere/blog/tags/ldap">ldap (9)</a></li>
1214
1215  <li><a href="https://people.skolelinux.org/pere/blog/tags/lego">lego (5)</a></li>
1216
1217  <li><a href="https://people.skolelinux.org/pere/blog/tags/lenker">lenker (8)</a></li>
1218
1219  <li><a href="https://people.skolelinux.org/pere/blog/tags/linuxcnc">linuxcnc (4)</a></li>
1220
1221  <li><a href="https://people.skolelinux.org/pere/blog/tags/lsdvd">lsdvd (2)</a></li>
1222
1223  <li><a href="https://people.skolelinux.org/pere/blog/tags/ltsp">ltsp (1)</a></li>
1224
1225  <li><a href="https://people.skolelinux.org/pere/blog/tags/madewithcc">madewithcc (3)</a></li>
1226
1227  <li><a href="https://people.skolelinux.org/pere/blog/tags/mesh network">mesh network (8)</a></li>
1228
1229  <li><a href="https://people.skolelinux.org/pere/blog/tags/multimedia">multimedia (44)</a></li>
1230
1231  <li><a href="https://people.skolelinux.org/pere/blog/tags/nice free software">nice free software (13)</a></li>
1232
1233  <li><a href="https://people.skolelinux.org/pere/blog/tags/noark5">noark5 (23)</a></li>
1234
1235  <li><a href="https://people.skolelinux.org/pere/blog/tags/norsk">norsk (320)</a></li>
1236
1237  <li><a href="https://people.skolelinux.org/pere/blog/tags/nuug">nuug (198)</a></li>
1238
1239  <li><a href="https://people.skolelinux.org/pere/blog/tags/offentlig innsyn">offentlig innsyn (40)</a></li>
1240
1241  <li><a href="https://people.skolelinux.org/pere/blog/tags/open311">open311 (2)</a></li>
1242
1243  <li><a href="https://people.skolelinux.org/pere/blog/tags/opphavsrett">opphavsrett (75)</a></li>
1244
1245  <li><a href="https://people.skolelinux.org/pere/blog/tags/personvern">personvern (114)</a></li>
1246
1247  <li><a href="https://people.skolelinux.org/pere/blog/tags/raid">raid (2)</a></li>
1248
1249  <li><a href="https://people.skolelinux.org/pere/blog/tags/reactos">reactos (1)</a></li>
1250
1251  <li><a href="https://people.skolelinux.org/pere/blog/tags/reprap">reprap (11)</a></li>
1252
1253  <li><a href="https://people.skolelinux.org/pere/blog/tags/rfid">rfid (3)</a></li>
1254
1255  <li><a href="https://people.skolelinux.org/pere/blog/tags/robot">robot (17)</a></li>
1256
1257  <li><a href="https://people.skolelinux.org/pere/blog/tags/rss">rss (1)</a></li>
1258
1259  <li><a href="https://people.skolelinux.org/pere/blog/tags/ruter">ruter (7)</a></li>
1260
1261  <li><a href="https://people.skolelinux.org/pere/blog/tags/scraperwiki">scraperwiki (2)</a></li>
1262
1263  <li><a href="https://people.skolelinux.org/pere/blog/tags/sikkerhet">sikkerhet (59)</a></li>
1264
1265  <li><a href="https://people.skolelinux.org/pere/blog/tags/sitesummary">sitesummary (4)</a></li>
1266
1267  <li><a href="https://people.skolelinux.org/pere/blog/tags/skepsis">skepsis (5)</a></li>
1268
1269  <li><a href="https://people.skolelinux.org/pere/blog/tags/standard">standard (74)</a></li>
1270
1271  <li><a href="https://people.skolelinux.org/pere/blog/tags/stavekontroll">stavekontroll (7)</a></li>
1272
1273  <li><a href="https://people.skolelinux.org/pere/blog/tags/stortinget">stortinget (14)</a></li>
1274
1275  <li><a href="https://people.skolelinux.org/pere/blog/tags/surveillance">surveillance (64)</a></li>
1276
1277  <li><a href="https://people.skolelinux.org/pere/blog/tags/sysadmin">sysadmin (5)</a></li>
1278
1279  <li><a href="https://people.skolelinux.org/pere/blog/tags/usenix">usenix (2)</a></li>
1280
1281  <li><a href="https://people.skolelinux.org/pere/blog/tags/valg">valg (9)</a></li>
1282
1283  <li><a href="https://people.skolelinux.org/pere/blog/tags/verkidetfri">verkidetfri (20)</a></li>
1284
1285  <li><a href="https://people.skolelinux.org/pere/blog/tags/video">video (77)</a></li>
1286
1287  <li><a href="https://people.skolelinux.org/pere/blog/tags/vitenskap">vitenskap (4)</a></li>
1288
1289  <li><a href="https://people.skolelinux.org/pere/blog/tags/web">web (42)</a></li>
1290
1291 </ul>
1292
1293
1294     </div>
1295     <p style="text-align: right">
1296  Created by <a href="http://steve.org.uk/Software/chronicle">Chronicle v4.6</a>
1297 </p>
1298
1299   </body>
1300 </html>