railsのバージョンを指定する
$ gem list rails *** LOCAL GEMS *** rails (3.0.1, 3.0.0, 2.3.5, 2.2.2, 1.2.6)
$ rails -v Rails 3.0.1
$ rails _2.3.5_ -v Rails 2.3.5
$ alias rails2='rails _2.3.5_' $ rails2 -v Rails 2.3.5
$ gem list rails *** LOCAL GEMS *** rails (3.0.1, 3.0.0, 2.3.5, 2.2.2, 1.2.6)
$ rails -v Rails 3.0.1
$ rails _2.3.5_ -v Rails 2.3.5
$ alias rails2='rails _2.3.5_' $ rails2 -v Rails 2.3.5