2009 102: Difference between revisions

Latest revision as of 15:21, 3 December 2008

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.

Considering the difference between graphical / interactive software and textual / non-interactive, you could compare:

graphical / interactive	command-line / non-interactive
the GIMP or Photoshop	ImageMagick
FireFox	wget
Cinelerra or Final Cut	ffmpeg

So the difference is not simply whether a program uses graphics or not -- Command-line programs are designed to perform a very specific task, and typically are specified textually according to a strict syntax (command-line options, etc.) They are non-interactive in the sense that you start them up, they do their thing, and you get the result -- you don't typically influence them while they are running. However, you often can work interactively with these programs through cycles of making changes to a script, running it, observing the result and repeating.

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

Now you can print the postscript file, or view with a viewer like evince:

evince wget.ps

Necessary Tools / Topics

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

Concepts

man pages
command line options

Examples of wget

Start from these examples, culled from the web. Try the examples out, alter the options. Find the options used in the (printed) man page of wget. Collect working (or interesting non-working) commands in a text file, and add comments to remind yourself why they were noteworthy.

To download all the files in a "directory listing":

wget -r -np -nd http://example.com/packages/

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)

Assignment for next week

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

Chapter 4 introduces some Turtle Graphics!

@@ Line 1: / Line 1: @@
-[[Image:Construction.gif]]
+== Command Line Media / "Media Bashing" ==
-this page is under construction ;)
-== 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 [[pipeline | 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.
-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 [[pipeline | 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.
+Considering the difference between graphical / interactive software and textual / non-interactive, you could compare:
+{| class=border
+|graphical / interactive
+|command-line / non-interactive
+|-
+|the [[GIMP]] or Photoshop
+|[[ImageMagick]]
+|-
+|[[FireFox]]
+|[[wget]]
+|-
+|Cinelerra or Final Cut
+|[[ffmpeg]]
+|}
+So the difference is not simply whether a program uses graphics or not -- Command-line programs are designed to perform a very specific task, and typically are specified textually according to a strict syntax (command-line options, etc.) They are non-interactive in the sense that you start them up, they do their thing, and you get the result -- you don't typically influence them while they are running. However, you often can work interactively with these programs through cycles of making changes to a script, running it, observing the result and repeating.
 == 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 [http://www.sarahcharlesworth.net/series-view.php?album_id=34&subalbum_id=53 Modern History] (1978). The work, among many other works of interest, can be seen as part of the [http://www.muhka.be/toont_beeldende_kunst_detail.php?la=en&id=2590&subbase=actueel&jaartal= Order Of Things] exhibition, through the end of the year at the MuKHA, Antwerp.
+An exercise to build a simple tool to support visual comparison of front pages newssites a la Sarah Charlesworth's [http://www.sarahcharlesworth.net/series-view.php?album_id=34&subalbum_id=53 Modern History] (1978). The work, among many other works of interest, can be seen as part of the [http://www.muhka.be/toont_beeldende_kunst_detail.php?la=en&id=2590&subbase=actueel&jaartal= Order Of Things] exhibition until Jan 4, 2009 at the MuKHA, Antwerp.
 Exercise explores the principle of:
@@ Line 18: / Line 33: @@
 == Tutorial ==
-=== Getting acquainted with a tool ===
+=== 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]].
@@ Line 42: / Line 59: @@
 </source>
-Man has an option to output print-friendly postscript output. It's described on the "man" man page. (Now how would one look up the man page of the man command?).
+Man has an option to output print-friendly postscript output. It's described on the "man" man page. (That's right: "man man"!)
 <source lang="bash">
@@ Line 51: / Line 68: @@
 man -t wget > wget.ps
 </source>
+Now you can print the postscript file, or view with a viewer like evince:
 <source lang="bash">
@@ Line 56: / Line 75: @@
 </source>
-Start with example of how to rip the above page with wget.
+=== Necessary Tools / Topics ===
-& re-assemble with montage...
+* Shell basics: cd, pwd, mv, cp
+* Connecting to a "remote" server with ssh
+* public_html
+* scp
+* [[wget]]
+* [[ImageMagick]]: montage
-Using the date tool for automatically naming a file.
+=== Concepts ===
+* man pages
+* command line options
-In general build up from really simple CL exercises of using imagemagick, file manipulations (moving, renaming, copying, deleting)... Introducing public_html...
+=== Examples of wget ===
-Necessary Tools / Topics:
+Start from these examples, culled from the web. Try the examples out, alter the options. Find the options used in the (printed) man page of wget. Collect working (or interesting non-working) commands in a text file, and add comments to remind yourself why they were noteworthy.
-* basics shell / file manipulation: cd, pwd, mv, cp
-* remote connections with ssh
+* http://linuxgazette.net/issue70/chung.html
-* [[wget]]
+* http://tipotheday.com/2007/10/11/wget-some-quick-tips/
-* [[ImageMagick]]: convert, mogrify, montage
+* http://ubuntuforums.org/showthread.php?t=718549&page=2
-* [[find]]
-* public_html
+To download all the files in a "directory listing":
-* [[crontab]]
+<source lang="bash">
-* date
+wget -r -np -nd http://example.com/packages/
+</source>
-Concepts:
+=== Solutions ===
-* variable
-* backquoting
-* reading man pages
-* setting options
-A sample:
 <source lang="bash">
-wget -r -l1 --no-parent -A "*.jpg" "http://www.sarahcharlesworth.net/series-view.php?album_id=34&subalbum_id=53"
+wget -r -nd -np --follow-tags=img http://www.colourlovers.com -A.jpg,.jpeg
-mkdir images
+montage *.jpg ../public_html/montage.jpg
-find www.sarahcharlesworth.net -iname "*.jpg" -exec mv {} images \;
-montage images/* modern.png
 </source>
-== Turtle Graphics ==
+Blurps out this file: http://pzwart2.wdka.hro.nl/~tklok/montage.jpg
+(Notice the wget is run from a different directory the where the picture is placed)
+*http://pzwart2.wdka.hro.nl/~ebonetti/Emanuele/montage.png
+*http://pzwart2.wdka.hro.nl/~svilayphiou/techdaze/102/montage.jpg
+*http://pzwart2.wdka.hro.nl/~cbaronavski/static/hate.jpg
+== Assignment for next week ==
-[[Seymour Papert]]
+* Chapters 3 & 4 from [[Think Python]]
+* Exercises from the book plus the [[Think Python X3 | additional exercise]]
-* http://www.computerhistory.org/timeline/?year=1967
+Chapter 4 introduces some [[Turtle Graphics]]!
-* http://www.bfoit.org/itp/IntroCmds.html