Topics Covered:

• Robbie Ferguson and Christa Wells present live from the Category5 studios in Barrie, Ontario.
• {play 4:05}Our new transcoders are averaging around 5 episodes per day. We expect this to increase over the next week.
• {play 6:45}Shout out to long-time and new viewers.
• {play 12:32}Robbie is developing his own Content Management System, and he's having a blast writing sophisticated jQuery code.
• {play 14:31}Feature: Introduction to scripting in the Linux terminal, with multitasking.
  • Creating a directory to work in.
  • Using nano to edit a new script in the Linux terminal.
  • Adding a shebang and specifying the interpreter of our script.
  • Making your script executable with chmod +x.
  • Grabbing some high-resolution images from demo.cat5.tv/016.
  • Writing a simple bash script which uses wget to download five images from a web server.
  • Hard-setting the download speed of wget—in our case, so we have an apples-to-apples scenario, but you might use this to prevent your script from maxing out your Internet bandwidth.
  • Specifying the output file for wget downloads.
  • Writing a very simple timer so we know how long our script takes to complete.

    start=`date '+%s'`
    # do all your stuff
    end=`date '+%s'`
    echo $(($end - $start))

  • Making our bash script asynchronous / mutlitasking, so our tasks can run simultaneously rather than having to wait for each download to complete before beginning the next.
  • Timing the results: our timer demonstrates that multitasking the same commands to download images completed in only 41% of the time—69% faster time to completion of the same task.
  • Final script from this example:

    #!/bin/bash
    start=`date '+%s'`
    wget --limit-rate=200k http://demo.cat5.tv/016/DSC_0273.JPG -O 1.jpg &
    wget --limit-rate=200k http://demo.cat5.tv/016/DSC_0343.JPG -O 2.jpg &
    wget --limit-rate=200k http://demo.cat5.tv/016/DSC_0477.JPG -O 3.jpg &
    wget --limit-rate=200k http://demo.cat5.tv/016/IMG_6290.JPG -O 4.jpg &
    
    wait
    
    mogrify -resize 640x360 *.jpg &
    
    wait
    
    end=`date '+%s'`
    
    echo $(($end - $start))
    
    echo done

  • What kind of downfalls are there to multitasking your script?
  • Adding mogrify to our script (as per Episode 310) but forcing it to wait for the downloads to complete before resizing the images.
  • Running PHP scripts on Linux from the command line.
  • Installing php5-cli, curl and php5-curl to build executable PHP code which utilizes the cURL library.
  • Break for the news
• {play 35:32}Top Stories from the Category5.TV Newsroom
  • The iPhone 5s TouchID was hacked within days of launch.
  • HP is stocking Ubuntu-powered laptops in 1,500 of its stores in China.
  • A new home theatre chair vibrates and pulses in time with your surround sound.
  • Valve has announced SteamOS – a Linux-based Steam operating system.
• {play 47:03}Feature (Resume): Continuing where we left off before the news.
  • Using cURL to load an external web site's HTML output into a PHP string.
  • Parsing an Apache file list into an array of filenames using PHP.
  • Looping through our array with foreach() to create a string containing a dynamically-generated bash script.
  • Using an incasesensitive search within a string in PHP.
  • Saving a string as a file in PHP with file_put_contents().
  • Final script from this example:

    #!/usr/bin/php
    ?php
      $ch = curl_init();
      curl_setopt($ch, CURLOPT_URL, 'http://demo.cat5.tv/016/');
      curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
      curl_setopt($ch, CURLOPT_HEADER, 0);
    
      $data = curl_exec($ch);
      curl_close($ch);
    
      $cleaned = strip_tags($data,'');
      preg_match_all("/]*)href=\"([^\"]*)\"(?:[^>]*)>(?:[^<]*)<\/a>/is",$cleaned,$matches);
    
      $output = '';
      foreach ($matches[1] as $filename) {
        if (stristr($filename,'.jpg')) $output .= 'wget --limit-rate=200k http://demo.cat5.tv/016/' . $filename . ' -O ' . $filename . ' &' . PHP_EOL;
      }
      file_put_contents('phpoutput.sh','#!/bin/bash' . PHP_EOL . $output . PHP_EOL . 'wait');
      exec('chmod +x phpoutput.sh');
    ?' ?>

  • Creating our final script to execute the PHP script and then the output bash script.
  • Running a bash command (in our example, chmod) within PHP using exec().
  • Final script from this example:

    #!/bin/bash
    ./test.php
    ./phpoutput.sh
    
    mogrify -resize 640x360 *.jpg
    
    echo "done."