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Hacker Public Radio

Your ideas, projects, opinions - podcasted.

New episodes Monday through Friday.

Welcome to HPR the Community Podcast Network

We started producing shows as Today with a Techie 9 years, 7 months, 0 days ago. Our shows are produced by listeners like you and can be on any topic that "are of interest to Hackers". If you listen to HPR then please consider contributing one show a year. If you record your show now it could be released in 7 days.

Call for shows

We are running very low on shows at the moment. Have a look at the hosts page and if you don't see "2015-??-??" next to your name, or if your name is not listed, you might consider sending us in something.

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Latest Shows

hpr1763 :: Intro to Homebrewing

Beer! and the joy of making it.

Hosted by Alpha32 on 2015-05-06 and released under a CC-BY-SA license.
Listen in ogg, spx, or mp3 format. Comments (0)

I talk a bit about homebrewing, how to do it, what it is, and how to get started. If there is interest, I will do more in-depth shows on the topic, otherwise I will let it stand alone.


I ramble on about brewing your own beer. Here are a few internet resources to help you along:

This is my first episode ever, so any advice is greatly appreciated. My email is

hpr1762 :: HPR Audio Book Club 10

In this episode, the HPR_AudioBookClub reviews Revolution Radio by Seth Kenlon

Hosted by HPR_AudioBookClub on 2015-05-05 and released under a CC-BY-SA license.
Listen in ogg, spx, or mp3 format. Series: HPR_AudioBookClub | Comments (0)


In this episode, the HPR_AudioBookClub reviews Revolution Radio by Seth Kenlon. You can download this AudioBook for free from


  • Thaj: I really loved this book. It hits me in a lot of the right spots as a person. I thought it had a very cinematic feel about it. I enjoyed the story, but in many ways I enjoyed the world it was set in even more.
  • x1101: Slow start, but finally builds to a very engaging story exploring many interesting social and political issues
  • Pokey: Slow start, really liked the story right from the start, but found the setting a little far fetched.

We all liked the pace of the story, as well as the reading and the audio quality. Overall this is a very polished work, even though there is some noise intentionally added at times.


As usual, the HPR_AudioBookClub took some time to review the beverages that each of us were drinking during the episode

  • Thaj: I am a sad panda because they grocery store had no lemons to make my AWESOME homemade lemonade. Unfortunately, I had to resort to pre-made lemonade that tastes like sugar water. Check this nutritional information
  • x1101 Dogfish head 120 minute IPAThis beer has a nice hoppy and citrus nose to it with a smooth, silky mouth feel. This beverage features subtle hoppy notes and a slightly smoky finish. Also, ~15% ABV, so I might have been a touch loopy the rest of the show
  • Pokey had a Sam Adams Summer Ale. Nice flavor, but not a lot of it. Refreshing with a hint of citrus. Very drinkable, but not mind blowing. I suspect this beer appeals to a wide audience. I've been on more of a "specialty" beer kick for a while, so this was almost disapointing.

Other Links

  • Catechism of a Revolutionary[Thaj]

    Street Candles by David Collins-Rivera

    We're still really excited about this AudioBook not only because the author is an HPR community member (lostinbronx), but also because the book is really good!

    David Collins-Rivera's personal blog:
    David Collins-Rivera's HPR correspondent page:


    Our next book club recording will be 2014/09/09T23:00:00+00:00. If you'd like a Google calendar invite, or if you'd like to be on the HPR_AudioBookClub mailing list, please get in contact with us on the HPR mailing list 'hpr at hackerpublicradio dot org'


    This episode was processed using Audacity We've been making small adjustments to our audio mix each month in order to get the best possible sound. It's been especially challenging getting all of our voices relatively level, because everyone has their own unique setup. Mumble is great for bringing us all together, and for recording, but it's not good at making everyone's voice the same volume. We're pretty happy with the way this month's show turned out, so we'd like to share our editing process and settings with you and our future selves (who, of course, will have forgotten all this by then).

    Mumble uses a sample rate of 48kHz, but HPR requires a sample rate of 44.1kHz so the first step in our audio process is to resample the file at 44.1kHz. Resampeling can take a long time if you don't have a powerful computer, and sometimes even if you do. If you record late at night, like we do, you may want to start the task before you go to bed, and save it first thing in the morning, so that the file is ready to go the next time you are.

    Next we use the "Compressor" effect with the following settings:

    • Threshold: -30db
    • Noise Floor: -50db
    • Ratio: 3:1
    • Attack Time: 0.2sec
    • Decay Time: 1.0 sec
    • "Make-up Gain for 0db after compressing" and "compress based on peaks" were both left un-checked.

    After compressing the audio we cut any pre-show and post-show chatter from the file and save them in a separate file for possible use as outtakes after the closing music.

    At this point we listen back to the whole file and we work on the shownotes. This is when we can cut out anything that needs to be cut, and we can also make sure that we put any links in the shownotes that were talked about during the recording of the show. We finish the shownotes before exporting the .aup file to .FLAC so that we can paste a copy of the shownotes into the audio file's metadata. We use the "Truncate Silence" effect with it's default settings to minimize the silence between people speaking. When used with it's default (or at least reasonable) settings, Truncate Silence is extreemly effective and satisfying. It makes everyone sound smarter, it makes the file shorter without destroying actual content, and it makes a conversations sound as easy and fluid during playback as it was while it was recorded. It can be even more effective if you can train yourself to remain silent instead of saying "uuuuummmm." Just remember to ONLY pass the file through Truncate Silence ONCE. If you pass it through a second time, or if you set it too agressively your audio may sound sped up and choppy.

    At this point we add new, empty audio tracks into which we paste the intro, outro and possibly outtakes, and we rename each track accordingly.

    We adjust the Gain so that the VU meter in Audacity hovers around -12db while people are speaking, and we try to keep the peaks under -6db, and we adjust the Gain on each of the new tracks so that all volumes are similar, and more importantly comfortable. Once this is done we can "Mix and Render" all of our tracks into a single track for export to the .FLAC file which is uploaded to the HPR FTP server.

    Remember to save often when using Audacity. We like to save after each of these steps. Audacity has a reputation for being "crashy" but if you remember save after every major transform, you will wonder how it ever got that reputation.


    If you liked Pirate Radio, you may also like The movies THX-1137, Logan's Run or The Illustrated Man.


    Thank you very much for listening to this episode of the HPR_AudioBookClub. We had a great time recording this show, and we hope you enjoyed it as well. We also hope you'll consider joining us next time. Please leave a few words in the episode's comment section.
    As always; remember to visit the HPR contribution page HPR could really use your help right now.

    The HPR_AudioBookClub

    P.S. Some people really like finding mistakes. For their enjoyment, we always include a few.

    1: The HPR_AudioBookClub doesn't laugh at anyone for reviewing tea, nor any other drink. We intentionally call the segment a "beverage review," not a "beer review" so that no one should feel alienated. Also because some of us drink wine.

    2: The HPR_AudioBookClub does laugh when people try to spell flavor with a "u"

    hpr1761 :: HPR Community News for April 2015

    HPR Community News for April 2015

    Hosted by HPR Volunteers on 2015-05-04 and released under a CC-BY-SA license.
    Listen in ogg, spx, or mp3 format. Series: HPR Community News | Comments (0)

    New hosts

    Welcome to our new hosts:
    amp, Stilvoid.

    Last Month's Shows

    Id Day Date Title Host
    1738 Wed 2015-04-01 Credit Card PIN breach Various Hosts
    1739 Thu 2015-04-02 Theater of the Imagination: Part 07 lostnbronx
    1740 Fri 2015-04-03 Mailing List Etiquette Dave Morriss
    1741 Mon 2015-04-06 HPR Community News for March 2015 HPR Volunteers
    1742 Tue 2015-04-07 How to Get Yourself On an Open Source Podcast - Presentation for Kansas Linux Fest, 22 March 2015 FiftyOneFifty
    1743 Wed 2015-04-08 Scale 13x Part 1 of 6 Lord Drachenblut
    1744 Thu 2015-04-09 Scale 13x Part 2 of 6 Lord Drachenblut
    1745 Fri 2015-04-10 51 - LibreOffice Impress - Overview and Guidance Ahuka
    1746 Mon 2015-04-13 Scale 13x Part 3 of 6 Lord Drachenblut
    1747 Tue 2015-04-14 Scale 13x Part 4 of 6 Lord Drachenblut
    1748 Wed 2015-04-15 Scale 13x Part 5 of 6 Lord Drachenblut
    1749 Thu 2015-04-16 Scale 13x Part 6 of 6 Lord Drachenblut
    1750 Fri 2015-04-17 xclip, xdotool, xvkbd: 3 CLI Linux tools for RSI sufferers Jon Kulp
    1751 Mon 2015-04-20 How I got into Linux Steve Bickle
    1752 Tue 2015-04-21 Penguicon 2015 Promo Ahuka
    1753 Wed 2015-04-22 Introducing a 5 year old to Sugar on Toast amp
    1754 Thu 2015-04-23 D7? Why Seven? Jon Kulp
    1755 Fri 2015-04-24 52 - LibreOffice Impress - Moving Around Ahuka
    1756 Mon 2015-04-27 Ranger File Manager b-yeezi
    1757 Tue 2015-04-28 Useful Bash functions Dave Morriss
    1758 Wed 2015-04-29 Cool Stuff part 3 Curtis Adkins (CPrompt^)
    1759 Thu 2015-04-30 A brief review of Firefox OS Stilvoid

    Mailing List discussions

    Policy decisions surrounding HPR are taken by the community as a whole. This discussion takes place on the Mail List which is open to all HPR listeners and contributors. The discussions are open and available on the Gmane archive.

    The main threads this month were:

    1. From: James Toebes <james@...>
      Date: 2015-04-01 09:58:54 -0400
      Subject: hpr1738 :: Credit Card PIN breach - THANK YOU HPR!
      Messages: 1

    2. From: Mike Ray <mike@...>
      Date: 2015-04-02 11:07:50 +0100
      Subject: Site links
      Messages: 4

    3. From: Mike Ray <mike@...>
      Date: 2015-04-02 23:16:34 +0100
      Subject: Off-topic: LibreOffice Calc questions
      Messages: 3

    4. From: Jon Kulp <jonlancekulp@...>
      Date: 2015-04-02 20:16:51 -0500
      Subject: HPR Email Bot malfunctioning?
      Messages: 3

    5. From: David Whitman <davidglennwhitman@...>
      Date: 2015-04-04 12:08:23 -0700
      Subject: Please reserve July 8 for davidWHITMAN
      Messages: 1

    6. From: Fifty OneFifty <fiftyonefifty@...>
      Date: 2015-04-04 14:56:04 -0500
      Subject: Who needs the Zoom H1 interview recorder next?
      Messages: 4

    7. From: Jon Kulp <jonlancekulp@...>
      Date: 2015-04-04 15:29:32 -0500
      Subject: Screencast: putting embedded audio into the ebooks
      Messages: 3

    8. From: Jonathan Kulp <jonlancekulp@...>
      Date: 2015-04-07 10:08:48 -0500
      Subject: Reserve May 11?
      Messages: 1

    9. From: Mike Ray <mike@...>
      Date: 2015-04-08 22:59:32 +0100
      Subject: LibreOffice Font Question
      Messages: 3

    10. From: Mike Ray <mike@...>
      Date: 2015-04-14 23:03:39 +0100
      Subject: API?
      Messages: 6

    11. From: Ken Fallon <ken@...>
      Date: 2015-04-16 20:04:21 +0200
      Subject: Disabling CSS on HPR for some tests
      Messages: 3

    12. From: Ken Fallon <ken@...>
      Date: 2015-04-24 13:31:56 +0200
      Subject: FTP Password has been Changed
      Messages: 1

    13. From: Dave Morriss <perloid@...>
      Date: 2015-04-28 21:52:55 +0100
      Subject: HPR Community News - next Saturday on 2015-05-02T18:00:00Z
      Messages: 1

    14. From: Ken Fallon <ken@...>
      Date: 2015-04-29 09:50:05 +0200
      Subject: Re: Hack in the Box Amsterdam security conference
      Messages: 1

    Total messages this month: 35

    Comments this month

    There are 24 comments:

    • hpr1726 (2015-03-16) "15 Excuses not to Record a show for HPR" by Knightwise.
      • Comment 3: Andres on 2015-04-06: "I uploaded one as a result of this"

    • hpr1732 (2015-03-24) "Renovating another Public-Domain Counterpoint Textbook" by Jon Kulp.
      • Comment 2: Robert Stackhouse on 2015-03-31: "Slashes"
      • Comment 3: Jonathan Kulp on 2015-04-05: "How do I do this? Watch this screen capture and see"

    • hpr1738 (2015-04-01) "Credit Card PIN breach" by Various Hosts.
      • Comment 1: JimZat on 2015-04-01: "Enlightening!"

    • hpr1741 (2015-04-06) "HPR Community News for March 2015" by HPR Volunteers.
      • Comment 1: Mike Ray on 2015-04-06: "Pearls before swine"

    • hpr1749 (2015-04-16) "Scale 13x Part 6 of 6" by Lord Drachenblut.
      • Comment 1: Jon Kulp on 2015-04-16: "inspirational!"

    • hpr1750 (2015-04-17) "xclip, xdotool, xvkbd: 3 CLI Linux tools for RSI sufferers" by Jon Kulp.
      • Comment 1: Jon Kulp on 2015-04-17: "Correction/Improvement"
      • Comment 2: Dave Morriss on 2015-04-21: "Fascinating stuff"
      • Comment 3: Mike Ray on 2015-04-21: "Terrific podcast"
      • Comment 4: Jon Kulp on 2015-04-21: "Thanks Mike; Response to Dave"
      • Comment 5: Jon Kulp on 2015-04-22: "Mike: ping me for help"
      • Comment 6: Mike Ray on 2015-04-23: "Blather and xvkbd as shortcuts in Debian"

    • hpr1754 (2015-04-23) "D7? Why Seven?" by Jon Kulp.
      • Comment 1: FiftyOneFifty on 2015-04-10: "Disapointed"
      • Comment 2: Jon Kulp on 2015-04-22: "confused"
      • Comment 3: thelovebug on 2015-04-28: "Dmaj7"

    • hpr1756 (2015-04-27) "Ranger File Manager" by b-yeezi.
      • Comment 1: Jon Kulp on 2015-04-28: "Ranger is phenomenal"

    • hpr1757 (2015-04-28) "Useful Bash functions" by Dave Morriss.
      • Comment 1: Bill Ricker on 2015-04-28: "epub"
      • Comment 2: Dave Morriss on 2015-04-28: "Re: epub"
      • Comment 3: 0xf10e on 2015-04-28: "exitcodes"
      • Comment 4: Dave Morriss on 2015-04-28: "Re: exitcodes"

    • hpr1758 (2015-04-29) "Cool Stuff part 3" by Curtis Adkins (CPrompt^).
    • hpr1759 (2015-04-30) "A brief review of Firefox OS" by Stilvoid.
      • Comment 1: Jon Kulp on 2015-04-30: "Welcome Aboard "

    hpr1760 :: pdftk: the PDF Toolkit

    Intro to the command-line pdf toolkit

    Hosted by Jon Kulp on 2015-05-01 and released under a CC-BY-SA license.
    Listen in ogg, spx, or mp3 format. Comments (1)

    Hacking Apart and Re-Assembling PDFs

    Extract pages 3–5 from file foobar.pdf:

    pdftk foobar.pdf cat 3-5 output excerpt.pdf

    Same thing but also grab the cover page:

    pdftk foobar.pdf cat 1 3-5 output excerpt.pdf

    Combine multiple PDFs:

    pdftk file1.pdf file2.pdf file3.pdf cat output combined.pdf

    Reassemble a 50-page document with all of the pages in reverse order (I once actually did this for my wife and she was very grateful—she had scanned an article at the library and it ended up with all of the pages in the wrong order from last to first. This command solved her problem in about one second.):

    pdftk wrongorder.pdf cat 50-1 output rightorder.pdf

    Check the pdftk man page for all kinds of other manipulations you can do, including "bursting" a PDF into its component pages, rotating pages in any direction, applying password protection, etc.

    Embedding “Bookmarks” as a Table of Contents

    You can also use pdftk to embed a table of contents in a flat PDF file. This is incredibly useful, as it can make large, unwieldy files very easy to navigate. All you have to do is add some bookmark data in a fairly straightforward format as shown below. As a starting point you should that dump the current metadata content of the file with this command:

    pdftk foobar.pdf dump_data_utf8

    Save the contents of this data dump in a text file and then add bookmark information just below the NumberOfPages value. Here is an excerpt from the huge anthology of public-domain scores I assembled for my music history class:

    InfoKey: ModDate
    InfoValue: D:20150106100000-06'00'
    InfoKey: CreationDate
    InfoValue: D:20150106100000-06'00'
    InfoKey: Creator
    InfoValue: pdftk 2.02 -
    InfoKey: Producer
    InfoValue: itext-paulo-155 (
    PdfID0: ece858bf9affbcad3b575cf3891a187f
    PdfID1: 23f89459e103dd43c6e7bc92028245c0
    NumberOfPages: 765
    BookmarkTitle: Beethoven: Symphony no. 5 in C minor Op. 67
    BookmarkLevel: 1
    BookmarkPageNumber: 205
    BookmarkTitle: Beethoven 5: I. Allegro con brio
    BookmarkLevel: 2
    BookmarkPageNumber: 205
    BookmarkTitle: Beethoven 5: II. Andante con moto
    BookmarkLevel: 2
    BookmarkPageNumber: 235
    BookmarkTitle: Beethoven 5: III. Allegro
    BookmarkLevel: 2
    BookmarkPageNumber: 256
    BookmarkTitle: Beethoven 5: IV. Allegro
    BookmarkLevel: 2
    BookmarkPageNumber: 275

    And here is the command to update the PDF with the table of contents embedded. This tells it to take the input file foobar.pdf and update its metadata using the file (with utf8 encoding) and output the results as foobar_with_toc.pdf.

    pdftk foobar.pdf update_info_utf8 output foobar_with_toc.pdf



    I made a screencast as a follow-up, showing the process of embedding bookmarks to make a table of contents:

    hpr1759 :: A brief review of Firefox OS

    I recently bought a Geeksphone Revolution and this is my review of running Firefox OS on it.

    Hosted by Stilvoid on 2015-04-30 and released under a CC-BY-SA license.
    Listen in ogg, spx, or mp3 format. Comments (2)

    This is phone I'm using:

    And here are some useful links about Firefox OS:

    The marketplace (app store):

    The marketing site:

    Developer documentation:

    hpr1758 :: Cool Stuff part 3

    CPrompt talks about some more cool stuff for you to check out!

    Hosted by Curtis Adkins (CPrompt^) on 2015-04-29 and released under a CC-BY-SA license.
    Listen in ogg, spx, or mp3 format. Comments (3)


    A part of PRX (Public Radio Exchange), they are a collection of story-driven podcasts sponsored in part by the Knight Foundation.

    PRX :

    Knight Foundation :

    Headed up by their flagship podcast 99% Invisible which is based on architecture and design and hosted by Roman Mars


    rxvt = Roberts XVT. X = X Window System, VT = VT102 terminal

    VT Terminal :

    rxvt started as a replacement for xterm. Written by Rob Nation

    Forked by Marc Lehmann and called rxvt-unicode or urxvt. Gave features such as transparency, Perl extensions and better font support

    Uses the .xdefaults configuration file in your home directory for customizations.

    Phil Plait's Crash Course Astronomy

    Also known as The Bad Astronomer

    Wikipedia :

    Blogs at Slate :

    Ted Talks :

    Crash Course on YouTube:

    hpr1757 :: Useful Bash functions

    Some Bash functions that may be of use in your scripts

    Hosted by Dave Morriss on 2015-04-28 and released under a CC-BY-SA license.
    Listen in ogg, spx, or mp3 format. Series: Bash Scripting | Comments (4)


    I enjoy writing Bash scripts to solve various problems. In particular I have a number of scripts I use to manage the process of preparing a show for HPR, which I am developing at the moment.

    My more complex Bash scripts use a lot of functions to perform the various tasks, and, in the nature of things, some of these functions can be of use in other scripts and are shared between them.

    I thought I would share some of these functions with HPR listeners in the hopes that they might be useful. It would also be interesting to receive feedback on these functions and would be great if other Bash users contributed ideas of their own.

    Full Notes

    Since the notes explaining this subject are long, they have been placed here:, and an experimental ePub version is available here:

    1. Bash Support Vim plugin:
    2. HPR episode Bash parameter manipulation:
    3. How to write functions (from The Linux Documentation Project):
    4. Download the pad and yes_no functions:

    hpr1756 :: Ranger File Manager

    Introduction to the ranger command line file manager

    Hosted by b-yeezi on 2015-04-27 and released under a CC-BY-SA license.
    Listen in ogg, spx, or mp3 format. Comments (1)

    From Man Page:

    ranger is a console file manager with VI key bindings. It provides a minimalistic and nice curses interface with a view on the directory hierarchy. The secondary task of ranger is to figure out which program you want to use to open your files with.

    This manual mainly contains information on the usage of ranger. Refer to the README for install instructions and to doc/HACKING for development specific information. For configuration, see the files in ranger/config. They are usually installed to /etc/ranger/config and can be obtained with ranger's --copy-config option.

    Inside ranger, you can press 1? for a list of key bindings, 2? for a list of commands and 3? for a list of settings.

    • Project page: Has pretty good documentation
    • Available on Debian, Arch, Probably others, git and mailing list available as well.



    • 3-pane view:
      • Previous -> current -> next
      • When current is a file, uses file magic and other programs to preview the file
      • optional dependencies for previews:
        • img2txt from caca-utils for ASCII-art
        • highlight for syntax highlights
        • atool for archives
        • lynx/w3m/elinks for html
        • pdftotext for pdfs
        • transmission-show for bittorrent information
        • mediainfo or exiftool for mediafile info
      • Color coded, with three themes to choose from
      • One more over to the right opens the file from other programs


    • located in ~/.config/ranger directory
    • rc.conf = keybindings and settings
    • = command-mode items
    • rifle.conf = file launcher options, which let you make custom file opener commands
    • = custom file preview scripts, like mdview
    • up, down, left, right, or h,j,k,l
    • gg top G Bottom
    • E edit
    • pageup/down

    Command commands

    • spacebar to mark or :mark for pattern
    • dd, yy, pp
    • :touch, :mkdir, :grep
    • del
    • rename and bulkrename (change from ranger.container.file import File to .fsobject.)
    • zh - toggle hidden
    • gn - new tab, gt or gT to navigate tabs
    • / search vile
    • V visual mode
    • :open_with
    • 1? = list key bindings
    • 2? list commands
    • 3? list settings
    • ? main help

    hpr1755 :: 52 - LibreOffice Impress - Moving Around

    Introduction to the Impress application screen layout.

    Hosted by Ahuka on 2015-04-24 and released under a CC-BY-SA license.
    Listen in ogg, spx, or mp3 format. Series: LibreOffice | Comments (0)

    Now we can start to take a look at the actual Impress application, and we begin by looking a how the program is laid out on the screen. Knowing where to find key features is important in using the program efficiently. For more go to

    hpr1754 :: D7? Why Seven?

    I explain what 7th chords are and when to use them.

    Hosted by Jon Kulp on 2015-04-23 and released under a CC-BY-SA license.
    Listen in ogg, spx, or mp3 format. Comments (3)

    In this episode I respond to one of the community-requested topics ("Music Theory") and try to explain what seventh chords are and why they are used. Below are some of the terms that I use in the course of the discussion.

    • Interval: The distance between two pitches (sounded either consecutively or simultaneously)
    • Consonance: Relatively stable sound between two or more pitches
    • Dissonance: Relatively unstable sound between two or more pitches. Dissonance often needs a "resolution" to consonance
    • Chord: three or more notes sounded together
    • Chord progression: a succession of chords
    • Triad: a chord with 3 pitches, the adjacent pitches separated by the interval of the 3rd.
    • Seventh chord: a chord with 4 pitches, the adjacent pitches separated by the interval of the 3rd.
    • Tonality: harmonic system that governs the use of major and minor keys
    • Tonic: the central tone of a piece of music
    • Mode: major or minor [e.g. Symphony no. 5 in C minor]
    • Modulation: the process of changing keys within a piece of music
    • Scale: Ascending or descending series of notes that define a key or tonality, with a specific arrangements of half-steps and whole-steps. Major and Minor scales are most common in Western music

    Free public-domain music reference book: Music Notation and Terminology by Karl Wilson Gehrkens: (see ch. 18)

    Free Online Music Dictionary: