2009 102

this page is under construction ;)

Command Line Media / "Media Bashing"

While the command line, or shell, is a text-based interface, this does not mean that manipulating other kinds of media, image, sound, video, is excluded. Far from it, many command line tools offer extremely useful and uniquely powerful functionality difficult to achieve with GUI programs. In addition, by applying the basics of pipelining and abstraction (through creating your own scripts with parameters), the command line enables highly particular and personal media tools to be created by pulling existing tools together in novel ways.

Making a "frontpage" snapshot tool

An exercise to build a simple tool to support visual comparison of front pages newssites a la Sarah Charlesworth's Modern History (1978). The work, among many other works of interest, can be seen as part of the Order Of Things exhibition until Jan 4, 2009 at the MuKHA, Antwerp.

Exercise explores the principle of:

• simple command line tools focused on doing a simple task
• the idea of a pipeline to join various commands together
• introducing the concept of a variable to make a personal "tool"
• cron jobs to automate a process over a long time period

Tutorial

Getting a grip on a tool

Command line programs, as focused and "simple" as they may be, often take some time to get used to. The initial man-page dump of possible options may seem overwhelming at first, but if you simply have a little discipline to try some variations, and above all to record your successes (in a text file and/or by taking notes on a printed copy of a man page), you can soon feel comfortable to use the new program.

We start with the tool wget.

First, simply try to run it:

wget

wget --help

Too much information! A pipeline to the rescue!

wget --help | less

man wget

Man has an option to output print-friendly postscript output. It's described on the "man" man page. (That's right: "man man"!)

man -t wget

man -t wget > wget.ps

evince wget.ps

Necessary Tools / Topics

• Shell basics: cd, pwd, mv, cp
• Connecting to a "remote" server with ssh
• public_html
• scp
• wget
• ImageMagick: convert, mogrify, montage

Concepts

• man pages
• command line options

Examples of wget

• http://linuxgazette.net/issue70/chung.html
• http://tipotheday.com/2007/10/11/wget-some-quick-tips/
• http://ubuntuforums.org/showthread.php?t=718549&page=2

Solutions

wget -r -nd -np --follow-tags=img http://www.colourlovers.com -A.jpg,.jpeg 
montage *.jpg ../public_html/montage.jpg

Blurps out this file:

(Notice the wget is run from a different directory the where the picture is placed)

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Assignment for next week

• Chapters 3 & 4 from Think Python
• Exercises from the book plus the additional exercise

Chapter 4 introduces some Turtle Graphics!