bundle-lock man page
bundle-lock — Creates / Updates a lockfile without installing
bundle lock [--update] [--local] [--print] [--lockfile=PATH]
Lock the gems specified in Gemfile.
Ignores the existing lockfile. Resolve then updates lockfile. Taking a list of gems or updating all gems if no list is given.
Do not attempt to connect to rubygems.org. Instead, Bundler will use the gems already present in Rubygems´ cache or in vendor/cache. Note that if a appropriate platform-specific gem exists on rubygems.org it will not be found.
Prints the lockfile to STDOUT instead of writing to the file system.
The path where the lockfile should be written to.
Updating All Gems
If you run bundle lock with --update option without list of gems, bundler will ignore any previously installed gems and resolve all dependencies again based on the latest versions of all gems available in the sources.
Updating a List of Gems
Sometimes, you want to update a single gem in the Gemfile(5), and leave the rest of the gems that you specified locked to the versions in the Gemfile.lock.
For instance, you only want to update nokogiri, run bundle lock --update nokogiri.
Bundler will update nokogiri and any of its dependencies, but leave the rest of the gems that you specified locked to the versions in the Gemfile.lock.