I recommend GPick:

    sudo apt-get install gpick

Applications -&gt; Graphics -&gt; GPick

It has many more features than gcolor2 but is still extremely simple to use: click on one of the hex swatches, move your mouse around the screen over the colours you want to pick, then press the &lt;kbd&gt;Space bar&lt;/kbd&gt; to add to your swatch list.

If that doesn&#39;t work, another way is to click-and-drag from the centre of the hexagon and release your mouse over the pixel that you want to sample.  Then immediately hit &lt;kbd&gt;Space&lt;/kbd&gt; to copy that color into the next swatch in rotation.

It also has a traditional colour picker (like gcolor2) in the bottom right-hand corner of the window to allow you to pick individual colours with magnification.

You can install the package `gcolor2` for this:

    sudo apt-get install gcolor2

Then:

    Applications -&gt; Graphics -&gt; GColor2



I have been very excited about MongoDb and have been testing it lately. I had a table called posts in MySQL with about 20 million records indexed only on a field called &#39;id&#39;.

I wanted to compare speed with MongoDB and I ran a test which would get and print 15 records randomly from our huge databases. I ran the query about 1,000 times each for mysql and MongoDB and I am suprised that I do not notice a lot of difference in speed. Maybe MongoDB is 1.1 times faster. That&#39;s very disappointing. Is there something I am doing wrong? I know that my tests are not perfect but is MySQL on par with MongoDb when it comes to read intensive chores. 

&lt;br&gt;
Note:

 - I have dual core  + ( 2 threads ) i7 cpu and 4GB ram
 - I have 20  partitions on MySQL each of 1 million records

**Sample Code Used For Testing MongoDB**

&lt;!-- language-all: lang-php --&gt;

    &lt;?php
    function microtime_float()
    {
        list($usec, $sec) = explode(&quot; &quot;, microtime());
        return ((float)$usec + (float)$sec);
    }
    $time_taken = 0;
    $tries = 100;
    // connect
    $time_start = microtime_float();
    
    for($i=1;$i&lt;=$tries;$i++)
    {
        $m = new Mongo();
        $db = $m-&gt;swalif;
        $cursor = $db-&gt;posts-&gt;find(array(&#39;id&#39; =&gt; array(&#39;$in&#39; =&gt; get_15_random_numbers())));
        foreach ($cursor as $obj)
        {
            //echo $obj[&quot;thread_title&quot;] . &quot;&lt;br&gt;&lt;Br&gt;&quot;;
        }
    }
    
    $time_end = microtime_float();
    $time_taken = $time_taken + ($time_end - $time_start);
    echo $time_taken;
    
    function get_15_random_numbers()
    {
        $numbers = array();
        for($i=1;$i&lt;=15;$i++)
        {
            $numbers[] = mt_rand(1, 20000000) ;
    
        }
        return $numbers;
    }
    
    ?&gt;

&lt;br&gt;
**Sample Code For Testing MySQL**

    &lt;?php
    function microtime_float()
    {
        list($usec, $sec) = explode(&quot; &quot;, microtime());
        return ((float)$usec + (float)$sec);
    }
    $BASE_PATH = &quot;../src/&quot;;
    include_once($BASE_PATH  . &quot;classes/forumdb.php&quot;);
    
    $time_taken = 0;
    $tries = 100;
    $time_start = microtime_float();
    for($i=1;$i&lt;=$tries;$i++)
    {
        $db = new AQLDatabase();
        $sql = &quot;select * from posts_really_big where id in (&quot;.implode(&#39;,&#39;,get_15_random_numbers()).&quot;)&quot;;
        $result = $db-&gt;executeSQL($sql);
        while ($row = mysql_fetch_array($result) )
        {
            //echo $row[&quot;thread_title&quot;] . &quot;&lt;br&gt;&lt;Br&gt;&quot;;
        }
    }
    $time_end = microtime_float();
    $time_taken = $time_taken + ($time_end - $time_start);
    echo $time_taken;
    
    function get_15_random_numbers()
    {
        $numbers = array();
        for($i=1;$i&lt;=15;$i++)
        {
            $numbers[] = mt_rand(1, 20000000);
            
        }
        return $numbers;
    }
    ?&gt;

MySQL vs MongoDB 1000 reads

How to check if variable contains valid UUID/GUID identifier?

I&#39;m currently interested only in validating types 1 and 4, but it should not be a limitation to your answers.

How to test valid UUID/GUID?

I&#39;am looking for a color picker utility on Ubuntu/Debian.
Anything simple and easy to use.

Color picker utility (color pipette) in Ubuntu

<p>I'am looking for a color picker utility on Ubuntu/Debian.
Anything simple and easy to use.</p>


Here&#39;s the console output:

    sergio@sergio-VirtualBox:~$ rvm list
    
    rvm rubies
    
       ruby-1.9.3 [ i386 ]
    
    sergio@sergio-VirtualBox:~$ rvm use 1.9.3
    Using /usr/share/ruby-rvm/gems/ruby-1.9.3

    sergio@sergio-VirtualBox:~$ ruby -v
    The program &#39;ruby&#39; can be found in the following packages:
     * ruby1.8
     * ruby1.9.1
    Try: sudo apt-get install &lt;selected package&gt;

So what&#39;s going on? Do I need to reboot my machine? Or should it work right off the bat? I&#39;m using Ubuntu 11.10, any help is appreciated.

Installed Ruby 1.9.3 with RVM but command line doesn&#39;t show ruby -v

I&#39;m trying to install trac and mod_wsgi over SSL. I tried to manually install it, but that didn&#39;t work out so well so I started to follow this: [trac-on-ubuntu](http://robertbasic.com/blog/trac-on-ubuntu/)

I skipped the svn part because I&#39;d like to use git instead. After the first edit of httpd.conf:

    WSGIScriptAlias /trac /var/trac/apache/trac.wsgi
    
    &lt;Directory /var/trac/apache&gt;
        WSGIApplicationGroup %{GLOBAL}
        Order deny,allow
        Allow from all
    &lt;/Directory&gt;

I restarted apache only to get this error:

    * Restarting web server apache2                                                    

    (98)Address already in use: make_sock: could not bind to address [::]:443

                                                                         [ OK ]

Doing these showed nothing.
   

     netstat -anp | grep 443 
     fuser 443/tcp

Doing this didn&#39;t yield anything except the grep command that I ran:

    ps -aux | grep httpd

Why is it saying that something else is using the port when there&#39;s nothing showing up?

**EDIT:** You guys are going to laugh at this. I had an extra Listen 443 in ports.conf that shouldn&#39;t have been there. Removing that solved this.

&quot;make_sock: could not bind to address [::]:443&quot; when restarting apache (installing trac and mod_wsgi)

I am using a Samsung galaxy nexus phone (**Android 4.0** platform) .

I am developing Android app on Ubuntu linux OS. I would like to run my application directly on the Samsung handset device, so I performed the following setup steps:

1. in my project `AndroidManifest.xml` file, added `android:debuggable=&quot;true&quot;` to the `&lt;application&gt;` element

2. On the device, in the **Settings &gt; Security** enabled **Unknown sources**

3. On the device, in the **Settings &gt; Developer options** enabled **USB debugging**

4. On my computer, created the `/etc/udev/rules.d/51-android.rules` file with the following content:

        SUBSYSTEM==&quot;usb&quot;, ATTR{idVendor}==&quot;04E8&quot;, MODE=&quot;0666&quot;, GROUP=&quot;plugdev&quot; 

5. On my computer, run the `chmod a+r /etc/udev/rules.d/51-android.rules` command

Then, on my computer I opened a terminal and executed the `adb devices` command, I got:

    List of devices attached 
    ????????????	no permissions

Since I did not see my device but only `???????????? no permissions`, I then run the following commands:

     adb kill-server
     adb start-server
     adb devices

But I still got:

    List of devices attached 
    ????????????	no permissions

Why? What am I missing?



set up device for development (???????????? no permissions)

I&#39;m running Ubuntu 11.10 and have run `sudo apt-get install jenkins` to install Jenkins on this system.

I&#39;ve seen some tutorials on how to setup a reverse proxy (Apache, Nginx, etc), however this is a VM dedicated for just jenkins and I&#39;d like keep it as lean as possible while having jenkins running on port 80.

I&#39;ve found the upstart config in `/etc/init/jenkins.conf` and modified the port to 80 `env HTTP_PORT=80`

When I start jenkins via `service jenkins start`, `ps` reveals that it runs for a few seconds then terminates.

Is this because jenkins is running as the `jenkins` user on a privileged port? If so, how do I fix this? Any other ideas a welcome.

Here is the upstart config:

    description &quot;jenkins: Jenkins Continuous Integration Server&quot;
    author &quot;James Page &lt;james.page@ubuntu.com&gt;&quot;
    
    start on (local-filesystems and net-device-up IFACE!=lo)
    stop on runlevel [!2345]
    
    env USER=&quot;jenkins&quot;
    env GROUP=&quot;jenkins&quot;
    env JENKINS_LOG=&quot;/var/log/jenkins&quot;
    env JENKINS_ROOT=&quot;/usr/share/jenkins&quot;
    env JENKINS_HOME=&quot;/var/lib/jenkins&quot;
    env JENKINS_RUN=&quot;/var/run/jenkins&quot;
    env HTTP_PORT=80
    env AJP_PORT=-1
    env JAVA_OPTS=&quot;&quot;
    env JAVA_HOME=&quot;/usr/lib/jvm/default-java&quot;
    
    limit nofile 8192 8192
    
    pre-start script
        test -f $JENKINS_ROOT/jenkins.war || { stop ; exit 0; }
        $JENKINS_ROOT/bin/maintain-plugins.sh 	
        mkdir $JENKINS_RUN &gt; /dev/null 2&gt;&amp;1  || true
        chown -R $USER:$GROUP $JENKINS_RUN || true
    end script
    
    script
        JENKINS_ARGS=&quot;--webroot=$JENKINS_RUN/war --httpPort=$HTTP_PORT --ajp13Port=$AJP_PORT&quot;
        exec daemon --name=jenkins --inherit --output=$JENKINS_LOG/jenkins.log --user=$USER \
            -- $JAVA_HOME/bin/java $JAVA_OPTS -jar $JENKINS_ROOT/jenkins.war $JENKINS_ARGS \
            --preferredClassLoader=java.net.URLClassLoader
    end script



How to configure Jenkins to run on port 80

I am trying to kill a process in the command line for a specific port in ubuntu.

If I run this command I get the port:

    sudo lsof -t -i:9001

so...now I want to run:

    sudo kill &#39;sudo lsof -t -i:9001&#39;

I get this error message:

    ERROR: garbage process ID &quot;lsof -t -i:9001&quot;.
    Usage:
      kill pid ...              Send SIGTERM to every process listed.
      kill signal pid ...       Send a signal to every process listed.
      kill -s signal pid ...    Send a signal to every process listed.
      kill -l                   List all signal names.
      kill -L                   List all signal names in a nice table.
      kill -l signal            Convert between signal numbers and names.

I tried `sudo kill &#39;lsof -t -i:9001&#39;` as well


How to kill a process on a port on ubuntu

Is there a Webkit-specific CSS style that will allow me to control the color/size/style of the box around the color in an `input[type=color]`?  

I&#39;m setting the color and background color of the input already so it looks good with a cross-compatibility polyfill I&#39;m using for older Chrome and Firefox.  

Now that Chrome actually has a *color picker*, there&#39;s a box around the color which leaves a `1px` grey box floating in the middle of the input when both color and background color of the input are set to the same color. 

Is there some CSS to get rid of it, either by setting that box&#39;s width to 0, changing the style to `none`, or, at worst, setting the color to the same as the color and background color?

---
In this image, I&#39;m talking about the grey box around the white area and outside the green:

![Screenshot of color picker](https://i.stack.imgur.com/shFk8.png)

I&#39;ve found one workaround, which is to set a high enough padding that the box (the grey border and green contents) is squished to size 0.  But that&#39;s really hacky, and doesn&#39;t look very good over in Firefox.

Content Type	Original Author	Original Content on Stackoverflow
Question	leninzprahy	View Question on Stackoverflow
Solution 1 - Ubuntu	Seb	View Answer on Stackoverflow
Solution 2 - Ubuntu	Marvin Pinto	View Answer on Stackoverflow

Color picker utility (color pipette) in Ubuntu

Ubuntu Problem Overview

Ubuntu Solutions

Solution 1 - Ubuntu

Solution 2 - Ubuntu

How to test valid UUID/GUID?

MySQL vs MongoDB 1000 reads

Attributions