What is MIME type "text/x-ruby"?

A MIME type is a string that tells browsers and other tools how to handle a particular kind of file.

text/x-ruby is a non-standard MIME type used for files that contain Ruby code.
It signals that a file holds Ruby scripts, libraries, test specifications, and related configuration data. This helps text editors and code-processing tools apply the proper syntax highlighting and execution rules.

Code Execution: Files under this MIME type are meant to be interpreted by Ruby runtimes.
Syntax Highlighting: Editors use it to recognize Ruby’s syntax and structure.
Project Organization: It groups various files—like scripts and test specs—to smoothly operate within Ruby-centric projects.

Files may come with different extensions. For example, files with RB, RUBY, or SPEC indicate their Ruby basis.
Some files, though bearing this MIME type, can also be linked to other formats (like certain configuration or templating files) within projects that heavily use Ruby and related tools.
This designation makes it clear to systems and developers that the file should be processed as text with Ruby semantics, ensuring consistency across diverse development tools and environments.

Associated file extensions

.ruby, .spec, .rb, .tf, .rbi, .rbx, .eye, .thor, .rbs, .fcgi, .workflow, .ru, .hcl, .rbw, .god, .builder, .druby, .duby, .gemspec, .jbuilder, .mirah, .mspec, .nomad, .pluginspec, .podspec, .prawn, .rabl, .rake, .rbuild, .tftpl, .tfvars, .watchr

Usage Examples

HTTP Header

When serving content with this MIME type, set the Content-Type header:


    Content-Type: text/x-ruby

HTML

In HTML, you can specify the MIME type in various elements:


    <a href="file.dat" type="text/x-ruby">Download file</a>

Server-side (Node.js)

Setting the Content-Type header in Node.js:


    const http = require('http');    
    
    http.createServer((req, res) => {    
      res.setHeader('Content-Type', 'text/x-ruby');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

FAQs

Is text/x-ruby a standard MIME type?

No, the x- prefix indicates it is a non-standard or private MIME type not officially registered with IANA. However, it is the de facto standard used by most operating systems, web servers, and text editors to identify Ruby source code files and apply appropriate syntax highlighting.

Which file extensions are associated with text/x-ruby?

The primary extension is .rb, but this MIME type covers a vast ecosystem of Ruby-related files. It is commonly associated with build specs like .gemspec, task runners like .rake, and configuration files such as .ru (Rackup) or .thor.

Why does my browser download the .rb file instead of running it?

If your browser downloads a file as text/x-ruby, it means the server sent the raw source code instead of executing it. To run the script, you must configure an application server (like Passenger, Puma, or Unicorn) or enable CGI on your web server to process the Ruby code before sending a response.

Why are my Terraform (.tf) files detected as text/x-ruby?

Terraform uses HCL (HashiCorp Configuration Language), which shares some syntactic similarities with Ruby. Many older MIME databases or generic text editors lack a specific definition for HCL, so they fallback to identifying .tf and .hcl files as text/x-ruby to provide basic syntax coloring.

Is it a security risk to serve text/x-ruby files?

Yes, if you intend to run a web application, serving files as text/x-ruby exposes your raw source code to the public. This can lead to source code disclosure vulnerabilities, potentially revealing database passwords, API keys, or proprietary logic to anyone who views the file.

How do I configure Apache to serve Ruby files as plain text?

If you intentionally want to display code snippets for a tutorial, you can force the MIME type in your .htaccess or config file. Use the directive AddType text/x-ruby .rb .gemspec to ensure browsers treat the files as downloadable or viewable text rather than attempting to execute them.

What software can open files with the text/x-ruby MIME type?

Since these are plain text files, they can be opened by any basic text editor like Notepad or TextEdit. However, for development, it is best to use specialized editors like VS Code, RubyMine, or Sublime Text, which utilize the MIME type to provide helpful syntax highlighting and code completion.

General FAQ

What is a MIME type?

A MIME (Multipurpose Internet Mail Extensions) type is a standard that indicates the nature and format of a document, file, or assortment of bytes. MIME types are defined and standardized in IETF's RFC 6838.

MIME types are important because they help browsers and servers understand how to process a file. When a browser receives a file from a server, it uses the MIME type to determine how to display or handle the content, whether it's an image to display, a PDF to open in a viewer, or a video to play.

MIME types consist of a type and a subtype, separated by a slash (e.g., text/html, image/jpeg, application/pdf). Some MIME types also include optional parameters.

How do I find the MIME type for a file?

You can check the file extension or use a file identification tool such as file --mime-type on the command line. Many programming languages also provide libraries to detect MIME types.

Why are multiple MIME types listed for one extension?

Different applications and historical conventions may use alternative MIME identifiers for the same kind of file. Showing them all helps ensure compatibility across systems.