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Revision as of 01:28, 14 October 2008

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Command Line Media

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, through the end of the year 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

Start with example of how to rip the above page with wget. & re-assemble with montage...

Using the date tool for automatically naming a file.

In general build up from really simple CL exercises of using imagemagick, file manipulations (moving, renaming, copying, deleting)... Introducing public_html...

Necessary Tools / Topics:

basics shell / file manipulation: cd, pwd, mv, cp
remote connections with ssh
wget
ImageMagick: convert, mogrify, montage
find
public_html
crontab
date

Concepts:

variable
backquoting
reading man pages
setting options

A sample:

wget -r -l1 --no-parent -A "*.jpg" "http://www.sarahcharlesworth.net/series-view.php?album_id=34&subalbum_id=53"
mkdir images
find www.sarahcharlesworth.net -iname "*.jpg" -exec mv {} images \;
montage images/* modern.png

Resources:

Turtle Graphics

Seymour Papert

@@ Line 19: / Line 19: @@
 === 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]].