git-flow completion requires git-completion to work. How exactly you go about installing git-completion varies wildly from system to system, so it's hard to give exact installation instructions.

By far the easiest way to install both Git and git-completion is via Homebrew, so you should pick that one.

1. Install homebrew

2. Install Git and bash-completion: brew install git bash-completion (Note: If this install fails with a 404 error, and you already have git installed, just remove the git part of this brew install)

3. Add bash-completion to your .bash_profile:

    if [ -f `brew --prefix`/etc/bash_completion ]; then
        . `brew --prefix`/etc/bash_completion
    fi
   

If you're using MacPorts, then you will need to install git-core with the +bash_completion option

sudo port install git-core +bash_completion

And add the following to your ~/.bash_profile or ~/.profile

if [ -f /opt/local/etc/bash_completion ]; then
    . /opt/local/etc/bash_completion
fi

1. Install Git and bash-completion: sudo apt-get install git-core bash-completion
2. I don't think you need to do anything else.

1. Install Git and bash-completion: sudo yum install git bash-completion
2. I don't think you need to do anything else.

1. Download and place git-flow-completion.bash in home directory (~/ in msysgit shell)

2. Add a .bashrc file to your home directory with the following line (or add this line to existing .bashrc file):

    source ~/git-flow-completion.bash
   

Note: The steps above have been tested to work with msysgit version 1.7.3.1 and newer, while completion does not function when tested with msysgit version 1.7.0.2. For best results, install the latest version of msysgit.

1. Download and place git-flow-completion.bash in %CYGWIN_INSTALLATION_DIR%\etc\bash_completion.d
2. Rename it to git-flow

Now you can autocomplete as following: git flow init etc.