how to make a gemset in RVM the default?

Use following command to make a gemset as default.

rvm use <ruby version>@<gemset name> --default

eg.

 rvm use 1.8.7-p370@mygemset --default

Have you tried specifying rvm --default use after the gemset is created so passing:

 rvm --default use [email protected]

and then seeing if that sticks? Using create and default at the same time isn't something I've tried before, it's the only thing that strikes me as out of place.

Given the discussion below I'd offer this as a means for dealing with the problem. (Personally, I'd probably implode rvm and start over.) But, if you wanted to try to make a go of it with this install then I'd look at your .rvm folder, specifically in .rvm/environments/default which will contain all the environment variables exported for the default environment. Here you'll find rvm_gemset_name this may be set incorrectly and isn't updated for some reason (permissions?) or is set correctly in which case its some other environment issue. You could try manually setting it here in the file if its not correct.

You can use this command.

rvm use --default <ruby version>@<gemset name>

or

rvm --default use <ruby version>@<gemset name> or

rvm use <ruby version>@<gemset name> --default