If you've just updated and your icons are all messed up, please restart Atom before filing an issue.

Some of the underlying icon fonts have updated and rearranged their icons, a restart will fix this.

Installing

On the command line:

apm install file-icons

On Atom:

Go to Preferences > Install, search for file-icons and install it.

file-icons

Adds file specific icons to atom for improved visual grepping. Works with Tree View and Fuzzy Finder and Tabs.

A number of icons and colours are provided by default for a range of common file types. If you have file that you would like custom icons for you can easily add this yourself.

File Icons are now specified via css(less) only.

No Colours

Disable colours in the settings.

Unity Theme

By default the Unity theme hides icons, you can force to show the icons in the settings

Customisation

The following css can be added to your user stylesheet to customise files with the .rb file extension.

@import "packages/file-icons/styles/colors"; // to use the colours
@import "packages/file-icons/styles/icons";  // to use the defined icons

@import "packages/file-icons/styles/items";
@{pane-tab-selector}, .icon-file-text {
  &[data-name$=".rb"]          { .medium-red;             } // Colours icon and filename
  &[data-name$=".rb"]:before   { .ruby-icon; .medium-red; } // Colours icon only
}

Folders

@import "packages/file-icons/styles/items";
@{pane-tab-selector}, .icon-file-directory {
  &[data-name=".git"]:before { .git-icon; }
}

Icons

Icons are located at ./stylesheets/icons.less. You can create a custom CSS class and express its code through content: "\fxxx";. Octicons is the default icon's class.

.ruby-icon { content: "\f047"; }

Fonts

Some custom fonts are already provided

FontAwesome(.fa)
FontMfizz(.mf)
Icomoon(.iconmoon)
Devicons(.devicons)

.coffee-icon { .fa; content: "\f0f4"; }

Colours

Colours are from the Base16 colour palette. CSS classes used to apply color follow its primary 8 (eight) colours and 3 (three) variants:

Red, Green, Yellow, Blue, Maroon, Purple, Orange, Cyan.
Light, Medium, Dark.

Medium is colour provided by Base16. Light is medium lightened 15%. Dark is medium darkened 15%. In order to "construct" a CSS class color, you provide its variant followed by a dash (-).

.light-red;
.medium-blue;
.dark-maroon;

Acknowledgments

Wouldn't have even tried to make this if it weren't for sommerper/filetype-color Also thanks to all the contributors.

chinayin/file-icons