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Privacy Is Personal

LinuxJournal - Thu, 2015, Jul02 - 07:00

Try to nail two boards together with your bare hands.

Can't be done. You need a hammer. But the power is not the hammer's. It's yours, because the hammer is your tool. As a tool, it becomes part of you. That's what tools do: they enlarge your capacity for action and effect.

That capacity is called agency. To have agency is to operate with effect in the world. more>>

July 2015 Issue of Linux Journal: Mobile

LinuxJournal - Wed, 2015, Jul01 - 08:30
Infinite Portal to the Universe, 12-Hour Battery Life

A few months back, I accidentally left my phone on the nightstand, and spent an entire day without my cell phone. more>>

PHP for Non-Developers

LinuxJournal - Tue, 2015, Jun30 - 07:00

After years of making it clear that I'm not a developer in just about every article I've written here at Linux Journal, I do have a confession to make. I can write the "Hello World" equivalent in almost every programming language out there. In assembly, it might have been "1+1", but my lack of advanced skills should be evident. more>>

A Code Boot Camp for Underprivileged Kids

LinuxJournal - Tue, 2015, Jun30 - 04:42

A science center in Johannesburg, South Africa, has opened the doors to a five-month course in Linux-based Web apps and entrepreneurial skills. The training is available free of charge to underprivileged students from nearby townships; if it's successful, it will be rolled out nationwide.

more>>

Comprehensive Identity Management and Audit for Red Hat Enterprise Linux

LinuxJournal - Mon, 2015, Jun29 - 08:07
Centrally managing Windows users, group policy and entitlements through Active Directory is a blessing for Windows IT, but leaves RHEL IT out in the cold. Native tools only go so far. more>>

Linux Kernel 4.1 Released

LinuxJournal - Fri, 2015, Jun26 - 09:16

Version 4.1 of the Linux kernel was released this week, and it includes a number of new features in the following areas. more>>

Secure Server Deployments in Hostile Territory

LinuxJournal - Thu, 2015, Jun25 - 11:25

Would you change what you said on the phone, if you knew someone malicious was listening? Whether or not you view the NSA as malicious, I imagine that after reading the NSA coverage on Linux Journal, some of you found yourselves modifying your behavior. The same thing happened to me when I started deploying servers into a public cloud (EC2 in my case). more>>

Take Control of Growing Redis NoSQL Server Clusters

LinuxJournal - Wed, 2015, Jun24 - 08:09

"When I started to develop Web applications in the mid- 1990s, I naïvely thought that more>>

Django Templates

LinuxJournal - Wed, 2015, Jun24 - 07:00

In my last article (February 2015), I explained how to create a simple Django project ("atfproject") and inside that, create a simple application (atfapp). The application worked in that if you went to the URL http://localhost:8000/hello/Reuven, you got the text "hello, Reuven". more>>

Attack of the Drones

LinuxJournal - Tue, 2015, Jun23 - 08:24

With the price and size of computer hardware steadily decreasing, it's becoming more viable to use embedded Linux systems to control small robots and drones. There are plenty of projects for Raspberry Pi, but not everyone wants to build a drone from scratch. That's why enthusiasts will be pleased to hear about the new drones from Parrot.

more>>

Physics Analysis Workstation

LinuxJournal - Tue, 2015, Jun23 - 07:00

CERN is the European Laboratory for Particle Physics. It has been in the news quite a bit lately with the discovery of the Higgs Boson at the Large Hadron Collider. Something that many people may not know is that it also has a long tradition of developing software for scientific use. more>>

The AtoMiC Toolkit!

LinuxJournal - Fri, 2015, Jun19 - 09:57

If you're a cord cutter (and a nerd), you most likely have a server or two dedicated to serving and possibly retrieving videos from the Internet. Programs like Kodi and Plex are awesome for media delivery; however, there's more to a complete system than just playing the videos. more>>

Plotting the temperature of your PI

AZ Loco - Thu, 2015, Jun18 - 22:40

If you are living in Arizona and you have a PI outside, you might want to keep an eye on its temperature. It might get a bit hot, and you might need to know how far you can push the PI before it starts acting funny...
So here is a recipe for doing this.

Assumptions:

I'm assuming that

  • you will use two systems: The PI, and a regular system, which I will refer to as the "PC."
  • Both are on the same network, and you can ssh into the pi, and you know the IP address of the PI, or it has a name you can somehow resolve into an IP address.
  • you use the account "pi" on the pi.
  • you have the plot utilities package installed
Shell script on the pi:
  • copy the text below into a file "thermal_recording.sh"

    --------------------------------------- #!/bin/bash while [ 0 ] ; do (echo -n $(date +"%s ") " " ;cat /sys/class/thermal/thermal_zone0/temp) >> temp_recordings ; sleep 60 ; done ----------------------------------------
  • run command

    chmod 755 thermal_recording.sh
  • To have script start on power-up run command

    crontab -e

    and add this line:

    @reboot /home/pi/thermal_recording.sh

Set up ssh login without password
  • on the PC, if you do not already have a file ~/.ssh/id_rsa.pub, run the command
    ssh-keygen
    You can give empty responses to all prompts.
  • scp the file ~/.ssh/id_rsa.pub to the pi
  • on the pi, append the content of the transferred file to file .ssh/authorized_keys
    cat ~/id_rsa.pub >> .ssh/authorized_keys
  • verify that you can ssh into the pi without the need of a password
If you want to publish your work to a web site, set up an appropriate folder there. Set up the PC side of things
  • create a folder ~/bin
  • create the file ~/bin/temp_plot.sh with the content below. Adjust the variables DIR, PI_IP, and (if you desire so) PUBLISH_URL

    --------------------------------------------------- #!/bin/bash set -x #local variables: #folder in which the work happens and the url to which to publish DIR=temp_plot_files PI_IP=xxx.xxx.xxx.xxx #leave this blank if you don't want to publish PUBLISH_URL="user@hostname:html_folder" #prep function. creates folder where the processing happens and #puts in the html template function prep { cd mkdir -p ${DIR} cd ${DIR} cat>abc.template<<EOF <html> <head> <script type="text/JavaScript"> <!-- function AutoRefresh( t ) { setTimeout("location.reload(true);", t); } // --> </script> </head> <body onload="AutoRefresh(100000)"> <b>replacing</b><hr> <img src=temp.png></img> </body> </html> EOF } #iter function. Does the work periodically function iter { rm -f `find . -type f | grep -v html | grep -v png|grep -v template` scp "pi@${PI_IP}:temp_recordings" . if [ $? -ne 0 ] ; then exit fi gnuplot <<EOF set terminal png set output 'temp.png' set grid back show grid set xtic 3600*24 set xdata time set timefmt "%s" set key outside bottom set format x "%m/%d" plot "temp_recordings" using (\$1-7*3600):(\$2/1000) smooth cspline with lines lw 4 title 'temp_centigrade' EOF cat abc.template | sed -e "s/replacing/$(date)/" > temp.html #publish if a url has been defined if [ "x${PUBLISH_URL}" != "x" ] ; then scp *.html *.png ${PUBLISH_URL}/. fi } prep while [ 0 ] ; do iter ; sleep 600 ; done ---------------------------------------------------------
  • run
    chmod 755 ~/bin/temp_plot.sh
  • on the PC, run the command
    crontab -e
    and add the following line

    @reboot ~/bin/temp_plot.sh
At this point you can reboot the PI and the PC, and the scripts should start running if you are lucky, you should see a working example here. Tags: Arizona Team Projects
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Practical Books for the Most Technical People on the Planet

LinuxJournal - Thu, 2015, Jun18 - 09:25
Linux Journal editors are proud to introduce GeekGuides-- practical ebooks for the most technical people on the planet. more>>

diff -u: What's New in Kernel Development

LinuxJournal - Wed, 2015, Jun17 - 13:15

When you run a program as setuid, it runs with all the permissions of that user. And if the program spawns new processes, they inherit the same permissions. Not so with filesystem capabilities. When you run a program with a set of capabilities, the processes it spawns do not have those capabilities by default; they must be given explicitly. more>>

LUCI4HPC

LinuxJournal - Tue, 2015, Jun16 - 12:07

Today's computational needs in diverse fields cannot be met by a single computer. Such areas include weather forecasting, astronomy, aerodynamics simulations for cars, material sciences and computational drug design. This makes it necessary to combine multiple computers into one system, a so-called computer cluster, to obtain the required computational power. more>>

Cinnamon 2.6 Released

LinuxJournal - Mon, 2015, Jun15 - 11:45

Cinnamon, one the default desktops of Linux Mint (alongside Mate) has recently been updated. Version 2.6 has a boatload of fixes, tweaks and improvements. Here are some of them: more>>

Gettin' Sticky with It

LinuxJournal - Thu, 2015, Jun11 - 14:12

In last month's issue, I talked about Linux permissions (see "It's Better to Ask Forgiveness..." in the May 2015 UpFront section). I could have covered SUID, GUID and sticky bit in the same article, but it seemed like a lot to cover in one sitting. more>>

Android Candy: Cloud Bonding

LinuxJournal - Tue, 2015, Jun09 - 13:48

Although the title might sound like some new-fangled tech jargon, I'm actually referring to a fairly simple Android app called "Unclouded." If you're a Dropbox user who also has things stored in Google Drive, Unclouded is a single interface to multiple file syncing backends. more>>

Jailhouse

LinuxJournal - Mon, 2015, Jun08 - 10:58

Because you're a reader of Linux Journal, you probably already know that Linux has a rich virtualization ecosystem. KVM is the de facto standard, and VirtualBox is widely used for desktop virtualization. Veterans should remember Xen (it's still in a good shape, by the way), and there is also VMware (which isn't free but runs on Linux as well). more>>

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