Environment variables

The environment variables the gem command and the RubyGems runtime respond to.

None of these are required. They override defaults per shell or per process, which makes them useful in CI, in version manager hooks, and for one-off experiments. Persistent preferences belong in a gemrc file instead. See Configuration.

Paths

Variable	Description
`GEM_HOME`	The directory gems are installed into. See Where gems are installed and how they load.
`GEM_PATH`	Directories searched for installed gems, separated by `:` on Unix and `;` on Windows.
`GEM_SPEC_CACHE`	The directory where gem specifications fetched from remote sources are cached. Defaults to `~/.gem/specs`, or to `$XDG_CACHE_HOME/gem/specs` when `~/.gem/specs` does not exist.
`GEMRC`	Additional gemrc files to read, separated by `:` on Unix and `;` on Windows. See Configuration.

Loading gems

Variable	Description
`RUBYGEMS_GEMDEPS`	Path to a gem dependencies file (`Gemfile`, `gem.deps.rb`, or `Isolate`) whose gems RubyGems activates automatically at startup. The special value `-` searches the current directory and its parents for one. Automatic discovery can execute code from a directory you do not control, so avoid `-` on multiuser systems.
`GEM_REQUIREMENT_<NAME>`	A version requirement applied when RubyGems activates the gem `<NAME>`, uppercased. For example, `GEM_REQUIREMENT_BUNDLER="~> 2.7"` restricts which Bundler version is activated.

Building and pushing gems

Variable	Description
`SOURCE_DATE_EPOCH`	A Unix timestamp used instead of the current time when packaging a gem, so that building the same input twice produces byte-identical `.gem` files.
`RUBYGEMS_HOST`	The gem server that `gem push` sends gems to when no `--host` is given.
`GEM_HOST_API_KEY`	An API key used to authenticate against the gem server instead of the key stored in `~/.gem/credentials`.
`GEM_HOST_OTP_CODE`	A one-time password for pushing when the account has multi-factor authentication enabled. Equivalent to `--otp`.
`GEM_PRIVATE_KEY_PASSPHRASE`	The passphrase of the private signing key, read by `gem cert` and when building signed gems instead of prompting for it.

Network

Variable	Description
`HTTP_PROXY`, `HTTP_PROXY_USER`, `HTTP_PROXY_PASS`	The proxy server, and credentials for it, used for connections to gem servers.
`NO_PROXY`	Hosts that are connected to directly, bypassing the proxy.

Other

Variable	Description
`RUBYGEMS_PREVENT_UPDATE_SUGGESTION`	When set, the gem command never suggests running `gem update --system` after noticing a newer RubyGems release.

Bundler

Bundler variables are not listed here. Every setting understood by bundle config can also be set through a corresponding BUNDLE_* environment variable, for example BUNDLE_PATH or BUNDLE_WITHOUT. See bundle config.

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