• [1] http://www.bbc.co.uk/programmes/b01gk4xc
• [2] http://www.mujc.org/site/default.aspx?PageID=1

1. Reduce the need for backtracking by finding semantically equivalent packages.
2. Avoid needing to set up a backtrack point in some cases.
   • This has the side-effect of eliminating some O(e^n) runtime cases.
3. Optimise installability testing of packages affected by a hinted migration.
   • This has the side-effect of avoiding some O(e^n) runtime cases when the post-hint state does not trigger said behaviour.
   • There is a follow-up patch for this one coming in the third series to fix a possible bug for a corner-case (causing a valid hint to be incorrectly rejected when it removed an uninstallable package).
4. Reduce the number of affected packages to test when migrating items by using knowledge about semantically equivalent packages.
   • In some cases, Britney can now do free migrations when all binaries being updated replace semantically equivalent packages.
5. (Merge pending) Avoid many redundant calls to sort_actions() , which exhibits at least O(n^2) runtime in some cases.
   • For the dataset Rapha l submitted, this patch shaves off over 30 minutes runtime. In the particular case, each call to sort_actions takes 3+ minutes and it was called at least 10 times, where it was not needed.
   • That said, sort_actions have a vastly lower runtime in the runs for Debian (and presumably also Ubuntu, since no one complained from their side so far).

• First series (already merged)
• Second series (pending, to be merged Monday, the 11th of August)
• Third series (under development. Warning: the branch will be rebased if/as needed)

Rcpp reached a nice round milestone yesterday: 250 packages on CRAN now depend on it (as measured by Depends, Imports and LinkingTo declarations). The graph is on the left depicts the growth of Rcpp over time. Or at least since I started to write down some usage numbers: first informally, then via a script. Also displayed is the relative proportion of CRAN packages using it. Rcpp cleared the four per-cent hurdle just before useR! 2014 where I showed a similar graph (as two distinct graphs) in my invited talk. 250 is a pretty impressive, and rather humbling, number. From everybody behind Rcpp, I would like to say a heartfelt Thank You! to all the users and of course contributors.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

function mark_completed()   
  var http = new XMLHttpRequest();
  http.open("POST", http_post_url, false);
  http.setRequestHeader("x-api-user", global('HabitrpgUserid'));
  http.setRequestHeader("x-api-key", global('HabitrpgApiToken'));
  http.send();
  return(http.responseText); 
 
try   
  var result = mark_completed(); 
  catch(e)   
  var error = e.message; 
 

function query_task()   
  var http = new XMLHttpRequest();
  http.open("GET",http_get_url,false);
  http.setRequestHeader("x-api-user", global('HabitrpgUserid'));
  http.setRequestHeader("x-api-key", global('HabitrpgApiToken'));
  http.send();
  var p = JSON.parse(http.responseText);
  return p['completed'];
 
try   
  var task_completed = query_task(); 
  catch(e)   
  var error = e.message; 
 

• Fedora
• Gentoo
• Arch Linux

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

• elektraPluginOpen() is designed to allow each plug-in to do initialization if necessary.
• elektraPluginGet() is designed to turn information from a configuration file into a usable KeySet, this is technically the only function that is REQUIRED in a plug-in.
• elektraPluginSet() is designed to store the information from the keyset back into a configuration file.
• elektraPluginError() is designed to allow proper rollback of operations if needed and is called if any plugin fails during the set operation. This allows exception-safety.
• elektraPluginClose() is used to free resources that might be required for the plug-in.
• ELEKTRA_PLUGIN_EXPORT(Plugin) simply lets Elektra know that the plug-in exists and what the name of the above functions are.

1. remove all functions (and their exports) from the plugin that are not needed. For example not every plugin actually makes use of the elektraPluginOpen() function.
2. provide a basic contract as described above

$ ls -l /usr/bin/fping
-rwxr-xr-x 1 root root 31464 May  6 21:42 /usr/bin/fping

Related articles

• Lesser-known tool of the day: getcap, setcap and file capabilities (insecure.ws)
• Using File Capabilities Instead Of Setuid (wiki.archlinux.org)
• Safer suexec: from setuid to Linux capabilities (welldefinedbehaviour.wordpress.com)
• Kees Cook: easy example of filesystem capabilities (outflux.net)

$ sudo apt-get install -y leiningen
[...]
$ lein new scratch
[...]
$ cd scratch
$ lein repl
Downloading: org/clojure/clojure/1.3.0/clojure-1.3.0.pom from repository central at http://repo1.maven.org/maven2
Transferring 5K from central
Downloading: org/sonatype/oss/oss-parent/5/oss-parent-5.pom from repository central at http://repo1.maven.org/maven2
Transferring 4K from central
Downloading: org/clojure/clojure/1.3.0/clojure-1.3.0.jar from repository central at http://repo1.maven.org/maven2
Transferring 3311K from central
[...]

Startup script As soon as I log into my desktop, my startup script starts a few programs, including:

• gnome-settings-daemon: makes GTK applications look nice by applying my preferred theme amongst other things
• gnome-keyring-daemon: remembers ssh public keys for the duration of my session
• gnome-screensaver: locks the screen when I'm not around
• nm-applet: handles wifi and VPN connections
• git-annex: keeps my folders synchronized between machines

Because of a bug in gnome-settings-daemon which makes the mouse cursor disappear as soon as gnome-settings-daemon is started, I had to run the following to disable the offending gnome-settings-daemon plugin:

dconf write /org/gnome/settings-daemon/plugins/cursor/active false

Screensaver In addition, gnome-screensaver didn't automatically lock my screen, so I installed xautolock and added it to my startup script:

xautolock -time 30 -locker "gnome-screensaver-command --lock" &

to lock the screen using gnome-screensaver after 30 minutes of inactivity. I can also trigger it manually using the following shortcut defined in my ~/.i3/config:

bindsym Ctrl+Mod1+l exec xautolock -locknow

Keyboard shortcuts While keyboard shortcuts can be configured in GNOME, they don't work within i3, so I added a few more bindings to my ~/.i3/config:

# volume control
bindsym XF86AudioLowerVolume exec /usr/bin/pactl set-sink-volume @DEFAULT_SINK@ -- '-5%'
bindsym XF86AudioRaiseVolume exec /usr/bin/pactl set-sink-volume @DEFAULT_SINK@ -- '+5%'
# brightness control
bindsym XF86MonBrightnessDown exec xbacklight -steps 1 -time 0 -dec 5
bindsym XF86MonBrightnessUp exec xbacklight -steps 1 -time 0 -inc 5
bindsym XF86AudioMute exec /usr/bin/pactl set-sink-mute @DEFAULT_SINK@ toggle
# show battery stats
bindsym XF86Battery exec gnome-power-statistics

to make volume control, screen brightness and battery status buttons work as expected on my laptop. These bindings require the following packages:

• pulseaudio-utils
• xbacklight
• gnome-power-manager

Keyboard layout switcher Another thing that used to work with GNOME and had to re-create in i3 is the ability to quickly toggle between two keyboard layouts using the keyboard. To make it work, I wrote a simple shell script and assigned a keyboard shortcut to it in ~/.i3/config:

bindsym $mod+u exec /home/francois/bin/toggle-xkbmap

Suspend script Since I run lots of things in the background, I have set my laptop to avoid suspending when the lid is closed by putting the following in /etc/systemd/login.conf:

HandleLidSwitch=lock

Instead, when I want to suspend to ram, I use the following keyboard shortcut:

bindsym Ctrl+Mod1+s exec /home/francois/bin/s2ram

which executes a custom suspend script to clear the clipboards (using xsel), flush writes to disk and lock the screen before going to sleep. To avoid having to type my sudo password every time pm-suspend is invoked, I added the following line to /etc/sudoers:

francois  ALL=(ALL)  NOPASSWD:  /usr/sbin/pm-suspend

Window and workspace placement hacks While tiling window managers promise to manage windows for you so that you can focus on more important things, you will most likely want to customize window placement to fit your needs better.

Working around misbehaving applications A few applications make too many assumptions about window placement and are just plain broken in tiling mode. Here's how to automatically switch them to floating mode:

for_window [class="VidyoDesktop"] floating enable

You can get the Xorg class of the offending application by running this command:

xprop   grep WM_CLASS

before clicking on the window.

Keeping IM windows on the first workspace I run Pidgin on my first workspace and I have the following rule to keep any new window that pops up (e.g. in response to a new incoming message) on the same workspace:

assign [class="Pidgin"] 1

Automatically moving workspaces when docking Here's a neat configuration blurb which automatically moves my workspaces (and their contents) from the laptop screen (eDP1) to the external monitor (DP2) when I dock my laptop:

# bind workspaces to the right monitors
workspace 1 output DP2
workspace 2 output DP2
workspace 3 output DP2
workspace 4 output DP2
workspace 5 output DP2
workspace 6 output eDP1

You can get these output names by running:

xrandr --display :0   grep " connected"

Finally, because X sometimes fail to detect my external monitor when docking/undocking, I also wrote a script to set the displays properly and bound it to the appropriate key on my laptop:

bindsym XF86Display exec /home/francois/bin/external-monitor

• jitsi - Registers fine, seems to lack any sort of TURN/STUN support.
• ekiga - No sign of TLS registration support.
• twinkle - Not in testing. A recompile leads to no sign of an actual client starting up when executed.
• sflphone - Fails to start (Debian bug #745695).
• Empathy - Fails to connect. Doesn't show any useful debug.
• linphone - No TLS connect (Debian bug #743494).

• What is open source [software]? Software that allows free access to its source code (ergo open ), permitting analysis and any modifications to the original code. All these permissions are contained in a license included in the software. Note that the term open source is now applied to a lot of things other than software, and I assume there s a different definition for those cases.
• Who is the community behind open source software? Shauna pointed out that there are many kinds of projects and many kinds of communities backing them. As an example of a for-profit model, Shauna cited RedHat that offers Linux (an open source OS) for free and profits from support services. Some projects are supported by NGO s (example: Center for Open Science) with a specific objective, a series of other projects are volunteer-based or are the result of a hobby project. The contributors vary accordingly, they are not only programmers but also people with a non-technical background. In sum, there s a lot of variety in the open source community as a whole, details of sturcture vary case to case.
• Why is it important that women get involved in technology? Men and women are different because of a series of reasons, among them our biological composition, influences of society and life experiences. Technology is for everyone, male or female and we need to be able to design products that will suit everyone well. If the development team is comprised of only one sex or another, it s likely that factors will be overlooked or ignored and as a result not a democratic experience. Shauna gave some examples of this, such as a voice-powered location search software that could easily identify stereotypically male keywords but not many of interest to females. In addition to this, it s known that there is a severe workforce deficiency in the tech industry. One proposed solution is to encourage more women to follow a career in tech. The argument is based on the assumption that any boy who is remotely interested in tech has a high likelihood of studying tech, but not every girl. Often girls are not encouraged to stuy STEM-related topics and in many places tech is considered inappropriate for women. I ve read that tech companies engineering team is 12% female and 88% male. That number is consistent with the stats of female college grads for STEM majors. I think boys who love tech will keep getting into tech, but there are a lot of girls who could be great engineers if they only gave it a shot. Women should be encouraged to pursue a tech career not only so they ll get to work in such an incredible field but also so they can help assuage the gap in supply and demand present in the tech workforce today.
• Why is open source important? We don t always get everything we want/need from off-the-shelf software. The great thing about open source is that you are free to tweak the at will and add whatever features you d like. Sometimes there are even more important necessities, such as security requirements. With open source you don t need to just take the manufacturers word that the code is bullet proof; open it and check it out yourself. Another factor that increases the value of open source is its stability. As Linus Torvalds said, given enough eyeballs, all bugs are shallow . With so many developers opening, studying and testing the code, bugs are quickly identified and removed. The fact that open source software is free doesn t reflect negatively on the quality; to the contrary, plenty of open source software is the best that s out there.
• Why its important contribute to open source? To start, it s not written anywhere that you have to contribute. That said, it sure is nice if you do. I think there are two main reasons why people contribute. One is they want to give back to the open source community. The other is they want to add some missing detail, feature or entire product. Of course, usually if you need something, someone else does as well, then by supplying your own need you end up helping many people out on the way. But one thing that I think applies especially to students is it s a great way to gain experience. You have to fit in some practical learning along with all that theory and one can only be so enthusiastic about the CS projects done in school that are usually discarded at the end of the semester. By contributing to an open source project, you are doing something that s real and that people will actually use. You also have access to an incredible network of mentors who are real pros and more than willing to help you out. Maybe I ve just been lucky, but they are really nice people who won t snicker if you ask a stupid question. Well, maybe they do. But I haven t seen it happen and I m the queen of stupid questions. Many times this is their pet project, so they re thrilled to have your contribution. Another great thing is that you can choose what you want to work with. It s easy to find a tech internship out there, what s not easy is finding an interesting internship. You might work with something you dislike or (gasp) end up just bringing people coffee. But we do that stuff cause we need the work experience. With open source you have a huge array of projects you can work on, one of them is certain to suit your interests.
• How to become a contributor? When using an open source software, you might notice things you d like to change, or actual bugs. Let the development team know about it and be sure to also let them know if you think you can figure out the fix. And if that hasn t happened yet, try exploring Github s open source repositories and check out the Issues option (upper right corner). There s usually a list of bugs or wishlist features that you just might be the man/woman for.

1. Generate a key for each zone. This will produce a private key (which, as the name suggests, you should keep to yourself), a public key in a DNSKEY DNS record, and a DS DNS record. More on those in a minute. One thing to be wary of, if you re like me and don t want or need separate Key Signing and Zone Signing keys. You must generate a Key Signing key this is a key with a flags value of 257. Doing this wrong will result in all sorts of odd-ball problems. I wanted to just sign zones, so I generated a Zone Signing key, which has a flags value of 256. Big mistake. Also, the DS record is a hash of everything in the DNSKEY record, so don t just think you can change the 256 to a 257 and everything will still work. It won t.
2. Add the key records to the zone data. For tinydns, this is just a matter of copying the zone records from the generated key into the zone file itself, and adding an extra pseudo record (it s all covered in the tinydnssec howto).
3. Publish the zone data. Reload your BIND config, run tinydns-sign and tinydns-data then rsync, or do whatever it is PowerDNS people do (kick the database until replication starts working again?).
4. Test everything. I found the Verisign Labs DNSSEC Debugger to be very helpful. You want ticks everywhere except for where it s looking for DS records for your zone in the higher-level zone. If there are any other freak-outs, you ll want to fix those because broken DNSSEC will take your domain off the Internet in no time.
5. Tell the world about your DNSSEC keys. This is simply a matter of giving your DS record to your domain registrar, for them to add it to the zone data for your domain s parent. Wherever you d normally go to edit the nameservers or contact details for your domain, you probably want to do to the same place and look for something about DS or Domain Signer records. Copy and paste the details from the DS record in your zone into there, submit, and wait a minute or two for the records to get published.
6. Test again. Before you pat yourself on the back, make sure you ve got a full board of green ticks in the DNSSEC Debugger. if anything s wrong, you want to rollback immediately, because broken DNSSEC means that anyone using a DNSSEC-enabled resolver just lost the ability to see your domain.