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Illustrates GEM_HOME vs GEM_PATH
# Two ENV variables control the 'gem' command:
# GEM_HOME: the single path to a gem dir where gems are installed
# GEM_PATH: a standard PATH to gem dirs where gems are found
# A gem directory is a directory that holds gems. The 'gem' command will lay
# out and utilize the following structure:
# bin # installed bin scripts
# cache # .gem files ex: cache/gem_name.gem
# doc # rdoc/ri ex: doc/gem_name/rdoc
# gems # gem file ex: gems/gem_name/lib/gem_name.rb
# specifications # gemspecs ex: specifications/gem_name.gemspec
# As an example of usage:
export GEM_HOME=a
export GEM_PATH=a
gem install rack
gem list # shows rack
export GEM_HOME=b
export GEM_PATH=b
gem install rake
gem list # shows rake (not rack)
export GEM_PATH=a:b
gem list # shows rake and rack
# And if you set GEM_HOME=a:b, you will install into the 'a:b' directory :)

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@nicolasgarnil nicolasgarnil commented Nov 16, 2013



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@codeitagile codeitagile commented Aug 8, 2014

Very clear.


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@parhs parhs commented Oct 29, 2016

It seems that GEM_HOME works as GEM_PATH too for searching gems.


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@apoorv50 apoorv50 commented May 11, 2020


export GEM_HOME = a
export GEM_PATH = b

gem list     #shows rack and rake.

It still lists both the gems.

Seems like it GEM_PATH always has GEM_HOME in it. Wonder what are the default/initial values of GEM_PATH?

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