Installing VPython (Visual Python) on Linux

VPython on Linux is a pain to install because they recommend using WINE or compiling from source.  I was able to compile from source but it took over an hour to compile a special patched version of wxPython and then compile that into VPython.  It was a less than "fun" experience and requires knowledge of compiling.  I discovered this during Kirby Urner's Leveraging Python tutorial at DjangoCon US 2013. So I set out to find a better way with fellow attendee German Larrain.

We're waiting on a pull request to the main GitHub repo that fixes our problems however we figured out a way to install VPython using PIP.  Its as easy as using PIP ability to install from a GIT repo.  In the meantime, you can use German's fork of VPython at GitHub:

sudo pip install git+git://github.com/glarrain/vpython-wx.git

Edit (Nov. 2013):

The pull request mentioned above has been merged into the main VPython git repo.  However the installation instructions have changed due to the addition of the Numpy package and on my system I needed to install a newer WxPython (which much have been installed on my old system and why it wasn't on the original instructions).

Here's how I installed WxPython 2.9.4 on Ubuntu 13.10 (saucy -- no deb was available yet).  I couldn't get 2.9.5 to build on my system - it kept failing in the make process at random places. You do need GTK2 dev package (as indicated as the first command) if you do not have that installed yet and the gstreamer base dev package (second command).  If you get errors about missing .h files, then your system is missing a -dev version of some package that is indicated.

sudo apt-get install g++ libgtk2.0-dev freeglut3-dev libgstreamer0.10-dev libgstreamer-plugins-base0.10-dev python-dev libgtkglextmm-x11-1.2-dev libboost-python-dev libboost-signals-dev libboost-python-dev libboost-thread-dev tk
wget http://downloads.sourceforge.net/project/wxpython/wxPython/2.9.4.0/wxPython-src-2.9.4.0.tar.bz2
tar -xvf wxPython-src-2.9.4.0.tar.bz2
cd wxPython-src-2.9.4.0/wxPython
python build-wxpython.py --build_dir=../bld

Note the output that say something like -- we will need this later:

To run the wxPython demo you may need to:
 - set your PYTHONPATH variable to /home/peter/wxPython-src-2.9.4.0/wxPython
 - set your LD_LIBRARY_PATH to /home/peter/wxPython-src-2.9.4.0/bld/lib

Note that Numpy will take some time compiling all the C code on your system. I have an i7 with 8 cores it took a few minutes -- may look like it hangs, but be patient. Also, it may take some time for PIP to download the tarball depending on your internet connection speed -- it may look like it hangs downloading, but again be patient.

sudo pip install numpy
sudo pip install https://github.com/BruceSherwood/vpython-wx/archive/master.zip

At this point, we need to create .sh executable to run vidle.  Create a file named vidle.sh with the following text (replace paths with the stuff we noted above) and ensure this file is executable (chmod 777 vidle.sh).

export PYTHONPATH="/home/peter/wxPython-src-2.9.4.0/wxPython"
export LD_LIBRARY_PATH="/home/peter/wxPython-src-2.9.4.0/bld/lib"
python /usr/local/lib/python2.7/dist-packages/VPython-6.03-py2.7-linux-x86_64.egg/vidle/idle.py

Twitter Bootstrap JS: Using ButtonGroup (radio type) selected button in a form

This is the function that we use to watch which buttons have been activated in a Twitter Bootstrap `buttonGroup` of a radio type.  You need to have a hidden form field so the function can put the values from the selected buttons in there for your form post.

Using it is as simple as adding this to your document ready of your page.  The first argument of the function call is the id of the `buttonGroup` and the second argument is the id of the hidden input where the function will store the values of the activated buttons:

    $(document).ready(function() {
        watchButtonsRadio('#utilitiesLocatedBtnGroup', '#utilities_located');
    });

Add this function to the general or utility JS file that is loaded on every page:

function watchButtonsRadio(buttonGroup, hiddenInput) {
    $('button', $(buttonGroup)).each(function() {

        var originalValue = $(hiddenInput).val();

        //Convert booleans to numeric
        if (originalValue == 'true') {
            originalValue = 1;
        } else if (originalValue == 'false') {
            originalValue = 0;
        }

        if ($(this).val() == originalValue) {
            $(this).trigger('click');
        }

        $(this).live('click', function() {
            // Hidden by default doesn't trigger the change event so manually fire it
            $(hiddenInput).val($(this).val()).change();
            console.log(hiddenInput + ': ' + $(hiddenInput).val());
        });
    });
}

Judgemental Maps: Minneapolis

So true in many ways!

Tomcat7 Service Start/Stop Script

I'm posting this because I forget the script I used because I setup systems so infrequently.  Place this in a file called tomcat7 in /etc/init.d/ Be sure to sudo chmod 777 tomcat7 so it will run.

#!/bin/bash                                                                                                                                                                                                #                                                                                                                                                                                                          # tomcat7     This shell script takes care of starting and stopping Tomcat                                                                                                                                 
# Description: This shell script takes care of starting and stopping Tomcat
# chkconfig: - 80 20
#
## Source function library.
#. /etc/rc.d/init.d/functions
TOMCAT_HOME=/home/peter/tomcat
SHUTDOWN_WAIT=20

tomcat_pid() {
  echo `ps aux | grep org.apache.catalina.startup.Bootstrap | grep -v grep | awk '{ print $2 }'`
}

start() {
  pid=$(tomcat_pid)
  if [ -n "$pid" ] 
  then
    echo "Tomcat is already running (pid: $pid)"
  else
    # Start tomcat
    echo "Starting tomcat"
    ulimit -n 100000
    umask 007
    /bin/su -p -s /bin/sh root $TOMCAT_HOME/bin/startup.sh
  fi


  return 0
}

stop() {
  pid=$(tomcat_pid)
  if [ -n "$pid" ]
  then
    echo "Stoping Tomcat"
    /bin/su -p -s /bin/sh root $TOMCAT_HOME/bin/shutdown.sh

    let kwait=$SHUTDOWN_WAIT
    count=0;
    until [ `ps -p $pid | grep -c $pid` = '0' ] || [ $count -gt $kwait ]
    do
      echo -n -e "\nwaiting for processes to exit";
      sleep 1
      let count=$count+1;
    done

    if [ $count -gt $kwait ]; then
      echo -n -e "\nkilling processes which didn't stop after $SHUTDOWN_WAIT seconds"
      kill -9 $pid
    fi
  else
    echo "Tomcat is not running"
  fi
 
  return 0
}

case $1 in
start)
  start
;; 
stop)   
  stop
;; 
restart)
  stop
  start
;;
status)
  pid=$(tomcat_pid)
  if [ -n "$pid" ]
  then
    echo "Tomcat is running with pid: $pid"
  else
    echo "Tomcat is not running"
  fi
;; 
esac
exit 0

Yet another reason Twitter needs Two Factor Authentication

AP Hack Highlights Two Crucial Features Twitter Needs - Forbes

I swear they haven't added support for Google Authenticator or Yubikey because any publicity about Twitter is good publicity about Twitter, right?

Get with the program Twitter -- you need two factor authentication now more than ever.  It's not surprising I blogged about it just in February about the hacking of Burger King's Twitter account.

Code Python anywhere online via your browser - PythonAnywhere

Code Python anywhere online via your browser - PythonAnywhere

Totally awesome with Python, Bash, MySQL consoles... GitHub integration, etc.

SSH Tunnel to Remote MySQL (Port Forwarding)

ssh -f -L 13306:localhost:3306 root@example.com -p 10022 -N

We block access to production MySQL servers over port 3306 for security reasons.  Here is an example connection string that proxies localhost port 13306 to port 3306 on the target system.

We use a few switched to make this easier to use:

Use -f to force SSH to go into background just before the SSH session starts.  This way you can get still be prompted for passwords but then run this in background.  We like this because then we don't have to have an open terminal all the time.

The -L switch indicates port:host:remoteport format. In this case, listen to socket 13306 on localhost and proxy to remote host port 3306.

The -p switch is special.  You might have to connect to SSH on a remote host on a port other than the standard 22.  It is starting to become common practice to change the SSH port on remote hosts to something else for security reasons.  In this example, the remote host only responds to SSH on port 10022.

Using -N tells SSH to NOT execute remote commands.  Useful when all you want this SSH session to do is port forwarding.