/useful-unix

Primary LanguageShell

useful-unix

https://github.com/kklin/useful-unix/

For our workshop, we'll be building a simple script to convert YouTube videos to mp3 files. You'll learn about some basic command line skills in the process.

Try not to violate any copyright laws ;)

Your VM

  • Starting the VM:
    • Open VirtualBox
    • File -> Import Appliance
    • Select /tmp/workshop/useful-unix.ova
  • Enabling copy-paste:
    • Settings -> Advanced -> Shared Clipboard
      • Set to Bidrectional
  • User credentials
    • You shouldn't need it, but:
      • Username: useful-unix
      • Password: jo1nun1x

Unix Basics

Here are some commands and concepts that you'll find useful later:

  • variables:
    • To reference a variable, you need to precede it with a dollar sign
    • To set a variable, you just do variable="value". The lack of spaces is important!
    • e.g. name="Kevin" ; echo "Hello $name"
  • man $COMMAND: displays documentation about the command
    • e.g. man youtube-dl
  • cd: changes your current working directory. Basically, this changes where you are in your computer.
  • ls: list files in current working directory
    • You can also ls files that match a certain pattern. e.g. *ls .avi will list all files in the current directory that end in .avi.
  • mv $FILE $DEST: moves a file (or multiple files) to a different place
  • A for loop lets you do something for each item in an input. The general format is:
    • for item in $INPUT ; do command $item ; done
      • This takes each word in $INPUT, puts in the variable $item, and then executes the command command $item
    • An example is: for name in kklin nlsun atran victorchen shwang ianlee ; do echo $name lurvs unix ; done
    • If we want to loop over filenames in our current directory, we can replace $INPUT with a regex. For example, *for item in ** loops over all files, and *for item in .mp3 loops over all mp3 files.
  • sudo lets you run commands as root. Root can do anything, unlike normal users which are constrained by permissions. If you're interested in the details of permissions, you can ask the Unix team sometime :)
  • Quotes are important. If you don't quote multi-word arguments, commands will think that you're providing multiple arguments when you're really only providing one.
  • piping is a method of connecting multiple commands together. The output of one command becomes the input to another. | is the pipe character. For example:
    • fortune generates a random fortune (try it!)
    • cowsay $TEXT takes some text and makes it look like a cow.. is saying it
      • cowsay join unix
    • We could copy and paste the output of fortune to be the input to cowsay manually.. or we could pipe!
      • fortune | cowsay
    • Note that this isn't used in the ytmp3 script

Setting up ffmpeg

  • sudo apt-get install ffmpeg

Doing it by hand

Time for scripting!

You're going to be modifying the template in ytmp3

What if we want to fix the metadata for the mp3's?

  • loop through all the mp3 files
  • print out the filename
  • allow the user to set the song title and artist

Accessing Plex

  • Settings -> Network -> Adapter 1 -> Port Forwarding
  • Add a new rule where:
    • Host IP is 127.0.0.1
    • Host Port is 32400
    • Guest IP is 10.0.2.15
    • Guest Port is 32400
  • Now you can go to http://127.0.0.1:32400/web/index.html from outside the VM

Adding it to your PATH

  • Ask a sysadmin

Extra features (what would you like to add?)

  • Background processes
  • Only prompt for metadata if the appropriate option is set
  • Automatic metadata generation
  • Integrate it with automator on Mac