Some useful rbenv commands are:

commands - List all available rbenv commands
local - Set or show the local application-specific Ruby version
global - Set or show the global Ruby version
shell - Set or show the shell-specific Ruby version
install - Install a Ruby version using ruby-build
uninstall - Uninstall a specific Ruby version
rehash - Rehash rbenv shims (run this after installing executables)
version - Show the current Ruby version and its origin
versions - List installed Ruby versions
which - Display the full path to an executable
whence - List all Ruby versions that contain the given executable