Zsh

RVM requires :

The use of globs that can possible be empty (no matches). If you experience glob problems try setting 'setopt nullglob' in your zsh profiles.
Shell regex support via the operator =~. =~ appeared first in 4.3.5,(it was added in zsh-workers-23375. )

how can I tell if my version of zsh supports =~ ?

$ foo=baaaar; [[ $foo =~ ba*r ]] && echo "Your shell supports the =~ regex operator." || echo "Your shell does not support the =~ regex operator."
Your shell supports the =~ regex operator.
$ zsh --version
zsh 4.3.5

$ foo=baaaar; [[ $foo =~ ba*r ]] && echo "Your shell supports the =~ regex operator." || echo "I like sheep, they are soft and fluffy..."
zsh: condition expected: =~
$ zsh --version
zsh 4.3.4

How can I upgrade my zsh version?

version="4.3.10" ; mkdir -p ~/.src && cd ~/.src && curl -O -L --create-dirs -C - http://downloads.sourceforge.net/project/zsh/zsh-dev/$version/zsh-$version.tar.bz2?use_mirror=voxel && tar jxf zsh-$version.tar.bz2* && cd zsh-$version && ./configure --prefix=/ && make && sudo make install

If you're using zsh (possibly with oh-my-zsh) and your prompt displays the current directory as "~rvm_rvmrc_cwd", the fix to add the following to your shell file before sourcing rvm:

unsetopt auto_name_dirs

If you are using oh-my-zsh and you see something like this error:

pwd:4: too many arguments

This is caused by an alias and due to the sh style sourcing of a script using the '.' operator instead of 'source'. The alias looks like this:

# .oh-my-zsh/lib/aliases.zsh
alias .='pwd'

To avoid this either remove/comment the alias and/or escape the '.' to bypass the alias like so:

\. /file/being/sourced

The latest RVM HEAD properly escapes the sourcing '.' so this should no longer be an issue. Update (rvm get head) if you see this issue related to RVM scripts.

zsh + iTerm2

If you are using iTerm2's feature allowing you to open new tabs / windows and "Reuse Previous Tab's Directory" then you will want to add the following line to the bottom of your .zshrc

__rvm_project_rvmrc

zsh + oh my zsh

If you want to use oh my zsh be sure not to use the bundler package. If rvm should take care of everything this would do for you anyways.