Install Ubuntu Server

• Download an image from this site
• Select File > New… to and follow the instructions, choose the .iso file you downloaded as image file
• Deselect "Simple installation" – you want to configure your system yourself
• Start the new virtual machine and follow the instructions

Install VMware Tools

• Choose Virtual Machine > Install VMware Tools from the VMware menu, then:

^
# install required packages
sudo apt-get install build-essential psmisc

# m...

When you want to quickly boot from a drive or image in a virtual machine you do not need to setup up a VirtualBox machine. Often QEMU does the job well enough.

Install it:

sudo apt-get install qemu

To boot an ISO:

qemu-system-x86_64 -cdrom filename.iso

If you prepared a USB pen drive and want to test it, run it like this (/dev/sdx being your device name; you may need to sudo to access it):

qemu-system-x86_64 -hda /dev/sdx

Be aware that not everything runs smoothly in QEMU -- you might need to set up a _VirtualBox...

Automatically convert bitmap images like JPEGs, GIFs and PNGs to the crisp, clean, scalable vector art of EPS, SVG, and PDF with the world's best auto-tracing software.

The trick is this: send a low-resolution version of your image to the screen, and a high-resolution version to the printer.

When installing RMagick you may get an error messages like this:

Version 2.13.1:

checking for Ruby version >= 1.8.5... yes
checking for gcc... yes
checking for Magick-config... no
Can't install RMagick 2.13.1. Can't find Magick-config in /home/arne/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/var/lib/gems/1.8/bin

*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
d...

I prefer using Opera's "User mode" to toggle an outlining of HTML elements quickly. This helps greatly when you want to see the actual dimensions of elements, e.g. for floating elements inside containers, instead of opening up the Dragonfly inspector every time.

Navigate to View → Style → "Manage Modes..." and tick the checkboxes like in the attached image. Then, switch to the User Mode by pressing the shortcut (Shift+G for the 9.2-compatible layout or for the default layout with enabled "single-key shortcuts") and select "Outline" from...

Liquid Canvas is a JavaScript library which allows you to draw inside an HTML canvas element with an easy yet powerful description language.

It can be used to add graphics to your web page without ever touching an image creation tool such as The Gimp, Inkscape or Photoshop.

Check out the Demo and the basic example and then download version 0.3.

Sometimes you need to dynamically load an image and do something as soon as its loaded (when for example its size is already available).

With jQuery, this seems to work across browsers:

$('<img>')
  .attr('src', '')
  .load(function() {
    alert('fully loaded!');
  })
  .attr('src', '/the/real/image/url');

The shell variable PS1 holds your bash prompt. You might want to change it to serve your needs best. Here is how to:

General

• non-printing escape sequences in your prompt have to be inclosed in \[\e[ and \] so your shell can correctly count its prompt's length
• we recommend to highlight your prompt on production machines
• you can also [show different root prompts for each user](https://makandracards.com/makandra/9569-get-the-username-w...

Paperclip uses the imagemagick resize options like 100x50> , 100x50<, 100x50# etc to resize images.
See the link what options are available.

• ('!') Ignore Aspect Ratio
• ('>') Only Shrink Larger
• ('<') Only Enlarge Smaller
• ('^') Fill Given Area
• ('%') Percentage Resize
• ('@') Pixel Area Limit
• ('#') Crop thumbnail centrally and ensure the requested dimensions, not documented at imagemagick doc

When you need to bulk rename files you can not call "mv *.foo *.bar" to change the extension of all .foo files to bar (because bash resolves wildcards and replaces them with the list of matched files).

This works on linuxes who use the Perl version of the rename command (like Ubuntu):

rename 's/\.foo$/\.bar/' *

You can also use this to rename other parts of the file, e.g. from flag_en.png, flag_de.png etc. to just en.png or de.png:

rename 's/^flag_//' *

Note that we used $ and ^ to explicitly look at the ...

When you use the send_file method to send a local file to the browser, you can save resources on the application server by setting the :x_sendfile option to true. This option is activated by default for Rails 3, so you need to understand this.

What this option does is not to send any data at all, but rather set the local file path as a new response header:

X-Sendfile: /opt/www/awesome-project/shared/downloads/image.png

When the response comes back from Rails to...

Styling button tags across all major browsers is not easy.

Many times you should be fine by using the native button style a browser-OS-combination offers you. But if you are trying to style buttons with images (e.g. by nesting a span tag inside them as assigning a background to both button and span) it will look different on each browser.

Use this Sass snippet as a base style:

button
  border: 0
  padding: 0
  cursor: pointer
  overflow: visible // removes padding in IE
  &::-moz-focu...

A good tool to generate strong passwords and secrets is "apg". You can get it with

sudo apt-get install apg

To create a strong secret for sessions, hashed Paperclip paths, etc. say

apg -m128 -a1 -E\'\"

Arguments explained:

• The -m parameter defines the secret length
• -a1 makes apg choose from all 7-bit ASCII characters instead of just the alphabet
• -E\'\" excludes quote characters so you can easily paste the secret into a Ru...

You need to install the following packages before you can build the Paperclip gem:

sudo apt-get install imagemagick librmagick-ruby

When using virtual attributes, the attached trait can be useful to automatically copy errors from one attribute to another.

Here is a typical use case where Paperclip creates a virtual attribute :attachment, but there are validations on both :attachment and :attachment_file_name. If the form has a file picker on :attachment, you would like to highlight it with errors from any attribute:

class Note < ActiveRecord::Base
  has_attached_file :attachment
  validates_attachment_presence :a...

When Paperclip attachments should only be downloadable for selected users, there are three ways to go.
The same applies to files in Carrierwave.

1. Deliver attachments through Rails

The first way is to store Paperclip attachments not in the default public/system, but in a private path like storage inside the current release. You should prefer this method when dealing with sensitive data.

Make ...

The CSS Emoticons plugin is a simple jQuery plugin (and stylesheet) that allows you to turn any text emoticons on the page into cute little smiling faces with pure CSS3 styling (no images whatsoever).

In july Google announced a new version of their image serach tool Google Images. But you won't find it on the German google.de site. To reach the new - as I may say, very much better - tool from germany, you have to surf to images.google.com. Et voilà!

Captify is a plugin for jQuery written by Brian Reavis (@brianreavis) to display simple, pretty image captions that appear on rollover

The box shadows created rendered in IE by CSS3PIE look darker and are blurred differently than in browsers that render box-shadow natively.

If possible, try to be OK with this. If not, make an IE-only stylesheet that uses a different color and blur radius:

// Real browsers:
+box_shadow("0 4px 10px #bbb")

// IE with PIE:
+box_shadow("0 5px 15px #888")

We should try to package this solution in a neat way so we don't need different stylesheets.

See also this [cross-browser box-shadow comparison]...

Sometimes files attain executable-flags that they do not need, e.g. when your Windows VM copies them over a Samba share onto your machine.

From inside your Rails project directory call regularly:

geordi remove-executable-flags

Runs chmod -x on Ruby, HTML, CSS, image, Rake and similar files.

This script is part of our geordi gem on github.

When deploying Rails applications you might have noticed that JS and CSS are not cached by all browsers.

In order to force Apache to add expiry dates to its response, add the attached .htaccess to the public directory. This will add a header such as Expires: Thu, 07 Oct 2010 07:21:45 GMT to the httpd response.

Configuring Apache

Check that you have mod_expires enabled. You need it for the attached .htaccess to work:

sudo a2enmod expires

Configuring Nginx

You can add this:

With this plugin, you can create a scalable tooltip by just using a single background image for the tooltip body.