[ruby] How to install a specific version of a ruby gem?

You can use the -v or --version flag. For example

gem install bitclock -v '< 0.0.2'

To specify upper AND lower version boundaries you can specify the --version flag twice

gem install bitclock -v '>= 0.0.1' -v '< 0.0.2'

or use the syntax (for example)

gem install bitclock -v '>= 0.0.1, < 0.0.2'

The other way to do it is

gem install bitclock:'>= 0.0.1'

but with the last option it is not possible to specify upper and lower bounderies simultaneously.

[gem 3.0.3 and ruby 2.6.6]