Episode: 1247
Title: HPR1247: Recording Terrestrial Radio with bash scripts and cron jobs
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr1247/hpr1247.mp3
Transcribed: 2025-10-17 22:18:40

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Hi, this is John Culp in Lafayette, Louisiana, back with another episode of Hacker Public
Radio.
In this episode, I'm going to be talking about automated recording of terrestrial radio
using shell scripts and cron jobs.
First though, I want to go back and talk a little bit about episode 1197, which was the
last one that I did.
I just wanted to thank Ken Fallon for putting up the show so quickly.
It really only took him a day or two after the time that I put it on the server before
it was up and ready to go.
Also thanks to him for the tip on the SSH config file, which is in the home directory in
the .ssh directory, the config file where you can set up hostname aliases.
He suggested that I look into this because it essentially accomplished the same thing that
my script that I called it stick, where the script that I used to make it easier to secure
copy files to remote servers.
Incidentally, Tharo came up with the same tip for me on Identica.
And so thanks to both of them, that was an excellent tip.
But one thing that reminded me of was that on Linux, there's really more than one way
to do so many things.
And even though I didn't know about this config file where I could set up these hostname aliases
so easily, I was able to hack together a solution using the tools that I did know about.
And so for that, I'm grateful to Linux.
Let's see.
Also, thank you to Clotu and Frank for comments about the episode.
And I got an email from a guy named Dave in the UK somewhere.
He said that he looked at my markdown to LaTeX script and said that there's one part in
the script where I pipe the output through said maybe a dozen times.
And he said that that made him twitch.
And I thought that was really funny because that part of the script I've always thought
was a little bit hacky and was not very pleased with it.
He suggested that I store all of those said substitution commands in a said script and
then just call that script from inside the bash script.
And so I tried that out and it works great and probably speeds up the process.
So thank you very much Dave for that tip.
That was a really good idea.
Okay, so on today's episode, I wanted to talk about something I learned how to do over
the past weekend and that is to record terrestrial radio on the computer using the command line
and scripting it.
Now why would somebody want to do this?
Well, it's because there are still some shows that I like to listen to that are only
on terrestrial radio, but I'm so used to having podcasts which I can listen to anytime
I want that I find it extremely inconvenient to be tied down to a specific location or
a specific device at a specific time.
I'd like to be able to simply record it and then listen back when I want to kind of like
a personal video recorder except for radio, DVR except for radio.
Anyhow, the impetus for this came on Friday of last week when the theater department at
the university where I teach had coming up on the radio that evening, a production that
they had done for radio, like a radio theater kind of production, it was going to be on
at six o'clock and I just could not tune in at six o'clock, I've got family responsibilities
and so forth.
So that afternoon I started looking around for ways to record the radio.
I knew that I could stream the radio station on my computer because I had gone to the radio's
website and found a little listen here button.
It's our local national public radio affiliate, KRVS here in Lafayette, Louisiana and they've
got a very handy URL for streaming the radio content live.
So I got the URL and I tried streaming it in a couple of ways.
I used the excellent little command line audio player written by Jezra called SAP which
stands for simple audio player.
And I also used VLC, you can stream stuff using VLC and there might even be a command line
way to stream on VLC.
I've not ever tried the command line version of VLC but I have vaguely recall somebody telling
me about it.
I also was successful streaming the content using a package called MPG123.
So after I was able to stream the content, I needed a way to record it and I looked at
a couple of ways where you kind of route the sound from out of the output into the input
and record and it was a little bit ugly.
But then I found an excellent package called StreamRipper.
Now, StreamRipper allows you to specify a URL and it will just start recording that stream
to your hard drive as an MP3 file.
So this really seemed perfect.
It's available in the repositories for Arch and for Debian, both the systems that I
use and I imagine it's available in other distros repositories as well.
You can also go to sourceforge.net, let's see it's StreamRipper.sourceforge.net and you
can get various packages there and it's apparently available for Windows also.
I did not even know that and it has some graphical front ends that you can try out as well.
It hasn't been updated since 2009 but maybe it doesn't really need to be.
It seems to work just fine the way it is.
So I downloaded and installed the StreamRipper package and tried it out and found that it
worked okay.
It has quite a few command line options and so I fiddled around until I found out all
of the options that I wanted to use.
And the options that I decided to use are several.
Let's see the command I use has 1, 2, 3, 4, 5, 6 command line options to it.
The lowercase a option tells it to rip everything to a single file.
I believe by default it rips to multiple files.
Like if you were listening to some kind of internet music radio program that has separate
songs it would put each one of those songs in a separate file.
I assume my goal only was to rip everything to a big long file.
And maybe that is also where it seems like the other switch the capital A is a little bit
redundant to me but I use both of them anyway.
The capital A switch says don't create individual tracks.
Then there is an L switch which stands for length and that one takes an argument.
So you do hyphen L and then a length in seconds.
So to record a one hour show you would put 3,600 because it would be 3,600 seconds.
Then there is the S switch that says don't create a directory for each stream.
Then hyphen, hyphen, quiet, double dash, quiet will do the program without any console output
unless there is some kind of error.
And I decided to use this because I knew eventually I would be scripting it and I didn't want
to be getting a system email with the output from this script.
Then finally the D switch tells gives you an option to tell a specific directory to put
the recording in.
So the entire command then would be streamripper followed by the URL followed by the series
of command line switches that you want to use.
And in my case it is hyphen A, space hyphen capital A, space hyphen L, space 3600, space hyphen
S, space double dash, quiet, space dash D, space directory.
And all of that will take the stream that I want and record it in one great big file
for one hour without putting any output to the console and stick it in the directory that
I specify.
You can also do it without any option for length and that will just start recording indefinitely.
And once I confirmed that this worked and that it was recording where I wanted it to and
with all of the options working properly, it was time to make a cron job so that it would
record at the right time and just have it waiting for me when I want it.
Now the show that I like to listen to every day or that I would have like to listen to
every day is the news on our MPR affiliate which runs sadly from 4am to 5am every day.
Now that's not a time where I want to get up and listen to it.
At 5am they start playing cage and music and while I don't really have any big problem
with cage and music, I don't really want to hear it at 5 o'clock in the morning either.
That's when I would like to be able to hear the news.
So I want to be able to automate the recording of the news from 4 to 5am every day and then
just have it waiting for me when I got up and then I could listen.
So I stored all of my options in a script where if I ran it at the right time, it would
record it for the right duration and stick it where I wanted to.
Then what was left to do was to add a line to my Cron tab that would tell it when to
start and on what days.
I don't have to tell it how long, well I don't think you can really tell it how long in
a Cron job, the length of the recording is handled in the script itself.
So the Cron tab line to record Monday through Friday at 4am reads 0 tab 4 tab asterisk
tab 1 through 5 in other words, number 1 hyphen 5 tab and then you put the path to the
script.
Now I had never really done a Cron job before where I had to specify the days of the week.
So I was glad to see that there was a way to tell it every day except Saturday and Sunday.
For one of the other shows that I decided to start recording weekly, instead of 1 through
5 I just put SAT for Saturday that would make it record every Saturday at a certain
time.
I'm happy to report that for the last three days the script has worked just fine and
every morning I've gotten up to find my news program waiting for me and what I do to
get it to my laptop.
I have the script running on a server because my server is on all the time while my laptop
goes to sleep every night.
So in the morning when I want to get the news program I have another script that just
has the secure copy or actually the R sync command that will go and find the MP3 file of the
news program and then bring it over to my laptop and then I can sync it up with my iPod
and listen to it from there.
I wrote one other kind of script to use with this recording of terrestrial radio and this
one is one that I want to use if for example I just know I'm hearing something on the radio
right now that I'd like to record on this station all I have to do is type the name of
the script and it will immediately start recording the stream of that station.
And without any command line argument it will just start recording and then keep going
until I tell it to stop or I can ultimately supply a numerical value of minutes and that
will be the duration.
So I would say script name space I don't know 15 and that would tell it to record for
15 minutes.
Inside the script I have a definition of the length that says if you find a command line
argument that's a number then take that and multiply it by 60 to get the number of
seconds and then use that as the length for the recording.
And that works great I haven't had to use it that much it was just kind of fun to figure
out how to do it.
Well I guess that's about it really thanks a lot for listening.
I will see you next time on hacker public radio.
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