Archive for February, 2010

Using Linux at Work

02.24.10

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Use Linux at work—even if your PC runs Windows.

When I started using Linux, I wondered when I would get to actually use it “on the job”.  It wasn’t easy sometimes to work with a Windows-based computer—when there’s a skill set available that can help you do things faster on the computer.  This skill set is the Linux command shell, but as mentioned your computer runs Microsoft Windows.  What can you do??

At one job, I was able to install Perl.  At another job one had to submit a request (with business justification) to add software to a workstation.  Instead of Perl I thought “why not Python?”  Since both times it was a Windows XP Environment, I used the DOS command line (or “CMD” app) to execute the Perl or Python programs.

I used the DOS CMD because (at that time) I did not know about Cygwin.  Using the DOS CMD to execute programs is easy.  The difficult part is dealing with case-insensitivity (which hurts portability) and using a shell to navigate folders with spaces in the names is a real pain.

Using the DOS shell to execute programs is not the same as using Cygwin.  Cygwin is command shell that emulates a working Linux environment.  Installing Cygwin with the base packages is simple and will provide a good “starting point” for learning some shell commands.

Want to use Linux but your work computer is Mac OS-X?

OS-X (like Linux) is Unix-based.  It has a shell that’s known as “Terminal” and it is in the Applications/Utilities folder.  You can also (if the OS is 10.5 or later) use keystrokes (apple + Space bar) to show the “spotlight search” box at the top right and start typing Terminal.  When search finds “Terminal” then press ENTER and voila!  Say hello to the Darwin Terminal.

Darwin handles the basic stuff really well.  It’s capable of helping you learn Shell commands.  But it doesn’t do everything that a regular Linux distro does.  Darwin’s limits can be overcome by installing apps and libraries.  Most likely you will need your System Administrator’s help to get and install X11, MacPorts, or Fink to augment the BSD-derived Darwin environment.

Favorite CLI Linux Apps: Intro

02.19.10

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We’re talking about the Linux command line…again.  Don’t worry, I won’t bore you (hopefully). If you’re still on this page, I commend you.

Remember, a Linux user should never feel forced to use the terminal or “console”, but knowing how to use it will help you get the most out of Linux.  The speed, simplicity, and the consistency are what drive me to use it nearly every time I’m at a Linux Desktop.

Ok, here’s a list of programs that are typically not in a distro by default.  These programs are intentionally run from a terminal prompt.

Favorite Linux CLI Apps: Emacs

02.19.10

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Emacs text editor (also known as emacs21-nox*)

[*The GNU Emacs editor without X support] is not usually part of a distro install—but it should be.  When you need to quickly edit a text or config file, a shell command can open the file, let you save changes, and then return you to the shell prompt.  Default console-based text editors (pre installed) are vi or nano.  I’ve tried them both.  I like emacs better.  At the time of writing, Synaptic in Crunchbang Linux 9.04 shows the console emacs as “emacs21-nox”

There are split camps and heavy debates as to which is better.  Just google  “vi vs emacs”.  It is useless for me to jump on the debate bandwagon.  Just know that they are similar, but operate differently.  Both edit and save text in a console/terminal.  Both offer no formatting or styling like a GUI word processor.  However, vi is a “modal editor” meaning that you switch back and forth between “insert mode” (for typing) and “command mode” (to issue file, search, or text-related commands.  Emacs is all one mode, where keystroke combos invoke commands.

Forget the evangelism or the “he said/she said bull$h1t”.  Try them both and see what you like.  You can always uninstall an unwanted application program with Synaptic.

Favorite CLI Linux Apps: php5cli

02.19.10

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php5cli runs PHP commands in a shell

PHP is a scripting language used on many websites.  It allows a page to do “dynamic” things (such as changing a page’s appearance based on user input, time or date, etc.)

One of the things I do wtih php5cli (or php in the shell) is check a PHP script for errors.  This saves you the trouble of running your PHP-based web page in a browser (which may have bad side effects).  ??Bad side effects?? Sure, what if your page is supposed to overwrite a file, and then hits an error.  It may erase a perfectly-good file.  Ok, enough gloom and doom talk.  Let’s say you wanted to check “myPHPscript.php” for errors. Run the following command in a shell to check it for errors before it runs/executes.  The option is a lowercase L (l) not a digit.

php -l myPHPscript.php

Another good use of PHP in a terminal is to generate HTML code.  There’s a certain frustration in coding up an entire web site, and then needing to go back and make a change across all your pages.  A time (and headache) saver is to let PHP do the “heavy lifting” for you.  What does this mean?

Basically, you set up a series of instructions for a script to follow.  Then, based on your needs, you make the script “write” different output based on a variable whose value may change.  Sometimes this involves changing the size of table cells, but it could apply to writing an entire series of web pages.  It comes in way handy when you’re looping over database results (and deciding to print the 2nd line of an address to the page).

In summary, when you’d have to change the same attribute in many, many places, and change them a few times, manually finding the attribute (for example a web link), you don’t have to manually (not mention “tediously”) hunt for the item(s) you want to change.  Install php5cli with Synaptic (or other) package manager. This installs any needed dependencies.

Favorite CLI Apps: Imagemagick

02.19.10

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Imagemagick

Imagemagick is an awesome command-line based image manipulation tool.

[Paraphrased from the imagemagick manual:]

ImageMagick®, is a software suite to create, edit, and compose bitmap images. It can  read,  convert  and  write  images in a variety of formats. Use ImageMagick to translate, flip, mirror, rotate, scale, shear and transform  images, adjust image colors, apply various special effects, or draw text, lines, polygons, ellipses and Bezier curves.  ImageMagick  includes a number of command-line utilities for manipulating images. Most of you are probably accustom to editing images one at a time with a graphical user interface (GUI) with such programs  as gimp or Photoshop. However, a GUI is not always convenient. Suppose you want to process an image dynamically or you want to apply  the  same  operations  to  many images  or  repeat  a  specific  operation at different times to the same or different image. For these types of operations, the command-line image processing utility is appropriate.

To install imagemagick, use Synaptic, or issue the following command in a terminal

sudo aptitude install imagemagick

Visit my post on using Imagemagick to perform the same process on multiple images.

There are many examples on the imagemagick website.

Favorite CLI Linux Apps: Guake

02.19.10

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Guake and Yakuake are drop-down terminal shells

Guake, or (if it’s a K Desktop Environment) Yakuake are “drop-down terminal shells” that appear when you press a button (usually F12).

If you usually open a terminal with every log in to your Linux desktop, there’s a more convenient (not to mention laaazy) way.  Simply tell the OS to run Guake after your user’s successful login. In Openbox, you’d add it to your autostart.sh file

The Guake terminal will notify you that it has started, and then auto-hides itself until you “un-hide it” by pressing the F12 key.  When you’re done with your current command-line stuff, simply press F12 again and Guake gets out of your way.

Favorite CLI Linux Apps: Lynx

02.19.10

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Lynx is a text-only web browser that runs in the shell.

Lynx is useful tool for those times when you want to extract only the web links from a web page.  Install lynx using the Synaptic (or other) package manager.

To view the hyperlinks of a given web page (google.com in this example), issue the command

lynx -dump http://www.google.com

It can also behave in a similar way to wget when you want to view the HTML source code of a web page.  The command to view the HTML source code is

lynx -source http://www.example.com

Click the following link to view a post where we collected links to mp3 files to build an unattended download list for the wget command.  Another feature of Lynx is that it allows you to view your pages as a web crawler/robot such as googlebot might see them.

Favorite Linux Apps: Intro

02.12.10

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So far, we’ve been talking about using the command line to download files or make some repetitive work simpler.  We’ve also seen how to upgrade a Firefox Web browser in Ubuntu.

Today we’ll discuss general “tools” that a Linux user might need on a daily basis.  Most of these tools are (believe it/not) GUI applications.  You can lose time by slogging through a CLI solution only to learn you could have gotten the job done quicker with a GUI app.  But when the GUI app is clumsy or lacks a reliable batch process—I consider command line solutions.

So, with that, here are some tools/apps that I install to my Linux desktops.  Since I prefer Debian-based package management, GUI installs will reference “Synaptic” while command line install instructions will be “aptitude”.

Favorite Linux Apps: Audio & Video

02.12.10

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This one’s up to you.  There are so many to pick from, just check Synaptic.

Digital Audio Playback

For an iTunes-style program, try AMAROK, and for simple playback of audio files without hearing the audible “gap” between song cuts, try Aqualung.

Audio Editing

I have used Audacity for simple stereo-file (non-multitrack) audio editing.  It got the job done, but arguably, there are better tools available for semi-pro recording on a Linux system.

Digital Video/Media Playback

VLC is a reliable application that can play many multimedia formats.  VLC sometimes comes standard with a distro.

Video Editing

I haven’t done much video editing, but so far I’ve tried Kino and I found it really easy to use.

Favorite Linux Apps: Web Coding

02.12.10

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Linux Gui Applications for Website Design/Development

If you’ve got a site to develop or design, it’s easy to set up a working web server based environment in Linux. As stated in another post, you will need an IDE-style text editor (or at the very least you’ll need an editor that lets you keep several files open at the same time).

Run your pages using a web server such as Apache

While there are a few ways to do this, installing XAMPP for Linux by Apache Friends is simple.  It is free, well-documented, and you can set up a website very quickly.  By default, the web server is not started at boot time, (which to me is a plus) and starting/restarting can be controlled by issuing a command at the terminal.  XAMPP comes with MySQL and PHP 5, so it gives you just about everything you need to develop/create dynamic, database-driven web pages with the ability to reuse code (via PHP “include” directives).

Check your work in a few browsers to ensure consistency

If you’re running Linux it may seem a daunting task to evaluate your site’s appearance in Mac OS-X or Microsoft Windows.  Daunting yes, but you can come close.  Safari in Mac OS-X uses the “webkit” layout engine and you can view your pages in the konqueror web browser as a poor-man’s substitute.  It’s not perfect, but it’s close.  Mozilla firefox uses the Gecko layout engine so it won’t show you know how a site looks in Internet Explorer for Windows.  Firefox has a browser plugin called “IE Tabs” but I’m not sure if this reasonably captures the look and behaviour of the native IE.  Be sure to browse the Firefox Web Development add-ons page.