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Mergit is a way to merge a bunch of required files into one file.

This allows you develop, design, and test your ruby script using normal ruby best practices (rspec, etc.) and then distribute them as a single-file ruby script.

Some use cases include:

  • Administration scripts
  • Simple tools
  • Programs that need to work on any ruby without installing gems

My original use case

When I wrote the original mergit, my goal was to distribute development/build scripts to a variety of systems.

These scripts had the following requirements:

  1. The scripts needed to be easy to install.
    • Our developers hadn't had experience with Ruby yet. This is before ruby 1.9.2 was released!
    • We didn't have an in-house RPM server (which wouldn't help our Windows systems anyway).
  2. The scripts needed minimal or no requirements.
    • Bundler and RVM were new and a pain to automatically install.
    • Not all systems had the (easy) root access needed to install required gems or build tools.
    • All the CentOS systems had Ruby (>= 1.8.7 by default)
    • All the Windows systems could easily get a version of Ruby (a quirk of our development/build environment).
    • We had a mechanism to get a reasonably current ruby for Solaris.
  3. The scripts needed to work on Windows, Solaris, and CentOS.
  4. I wanted to write the scripts with the best practices; unit tests, one-class-per-file, SOLID design.
    • I needed the scripts to work reliably, so I needed good tests.
    • It was easier to work on if we followed SOLID design principles.

The scripts I wrote in the end could be installed on any development or build system via a simple curl and only required any working ruby of version 1.8.7 or greater.

This was possible because all the .rb files were merged into single files, including the one gem I needed (the pure ruby minitar).


Mergit uses simple text processing, therefore it can be tripped up. Some known problems include:

  • require statements nested in code instead of at outermost scope of a file will expand in-place. This probably isn't what you want.
  • The order required files are pulled in may be different than ruby.
  • The replacement feature is very brute force. Be careful using it.


Add this line to your application's Gemfile:

gem 'mergit', '~> 1.1'

And then execute:

$ bundle

Or install it yourself as:

$ gem install mergit

Note: Mergit uses Semantic Versioning.


Command Line Tool

The command line tool, mergit, is pretty self-explanatory.

You specify the ruby file you want requires merged into on the command line (via standard in, if you specify -) and any library directories you want required from.

You can specify the --lib flag multiple times.

There is also a --replace flag that lets you specify a string or regular expression (a string surrounded by /) that should be replaced.


bin/mergit --replace mouse=cat filename

This will replace all occurances of "mouse" with "cat".

You can specify the --replace flag multiple times.

Use the --output flag to send the resulting output to someplace other than stdout.

MERGIT directives

You can also cause any line to be skipped by adding a Mergit directive in a comment at the end of the line.


raise "This won't be in the merged output." # MERGIT: skip

Library API

Simple usage:

search_path = [ '/path/to/lib', '/path/to/other/lib' ]
mergit = => search_path)

string_of_merged_file = mergit.process_file('/path/to/file')
# or
string_of_merged_string = mergit.process(some_string)

For more detailed information, see the documentation.

Additional Notes

To use up less space, you can compress the resulting script with gzexe.


Level 1 -- Apprentice

File an issue.

Make sure it includes the steps needed to reproduce it as well as what you expected to happen.

Level 2 -- Journeyman

  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request

Level 3 -- Master

Repeat Level 2 until I give you write access on github. :-)