What is a .GEM file?
The .gem extension names both RubyGems packages and Digital Research GEM images.
RubyGems package
- What it is
- A RubyGems package - a TAR of the gem's code and metadata. Analyser lists its contents and reads the gemspec.
- How to tell it apart
- A RubyGem is a TAR archive (ustar at offset 257).
- Did you know
- Every `gem install` pulls down one of these .gem files - a TAR holding the code plus a YAML gemspec listing its dependencies.
- RubyGems was first released in 2004 by Jim Weirich, Chad Fowler and others, and from Ruby 1.9 in 2007 it shipped inside the language itself, making a package manager part of the standard install.
- Bundler, released in 2010, layered a lockfile on top of RubyGems so a project could pin every gem to an exact version and reproduce its dependency tree precisely.
GEM image / metafile
- What it is
- A Digital Research GEM raster image or metafile from the Atari ST and Ventura Publisher era. Analyser identifies it.
- How to tell it apart
- A GEM image has its own small binary header.
- Did you know
- GEM was Digital Research's 1985 graphical desktop; an Apple lawsuit forced changes that helped doom it, but its image format lived on across the Atari ST.
- GEM stands for Graphics Environment Manager, and a .gem is usually a vector metafile of drawing commands, distinct from the companion .img raster format.
- Caldera released the GEM source code under the GPL in April 1999, reviving it decades on as the community FreeGEM and OpenGEM projects.
- Depth of analysis
- .GEM is an identification-grade format: Analyser recognises it from its bytes and decodes the header metadata it carries, rather than opening it in a full viewer. Formats that do get a full viewer are marked "Full" on the formats page.
- Open a .GEM file
- Drag a .GEM file onto the Analyser home page (or tap to pick one). It is identified entirely in your browser - nothing is uploaded, there is no account, and it works offline once installed.