I was using RVM with .rvmrc files to switch Ruby versions and gemsets, but now warning messages are displayed.

You are using '.rvmrc', it requires trusting, it is slower and it is not compatible with other ruby managers,
you can switch to '.ruby-version' using 'rvm rvmrc to [.]ruby-version'
or ignore this warnings with 'rvm rvmrc warning ignore /Users/your_username/git/myapp/.rvmrc',
'.rvmrc' will continue to be the default project file in RVM 1 and RVM 2,
to ignore the warning for all files run 'rvm rvmrc warning ignore all.rvmrcs'.

Using /Users/your_username/.rvm/gems/ruby-2.0.0-p247 with gemset myapp

Apparently, there’s been a movement to unify configuration files across Ruby version management systems (rvm, rbenv, rbfu), so it seems better to split them into .ruby-version and .ruby-gemset files as shown below.

.rvmrc file

rvm use ruby-2.0.0-p247@mygemset

↓ Split .rvmrc into 2 files.

.ruby-version file

ruby-2.0.0-p247

.ruby-gemset file

mygemset

Of course, the traditional .rvmrc file can still be used, so if you want to ignore the warning in that case, you can run the following command:

rvm rvmrc warning ignore all.rvmrcs

Reference Information

・Use rvmrc or ruby-version file to set a project gemset with RVM? - Stack Overflow

・.rvmrcから.ruby-gemsetと.ruby-versionに移行 - Qiita [キータ]

・Rubyバージョン管理界にも統一球導入？

That’s all from the Gemba.