Way to describe remote branches and local references. The language for git-fetch command to decide how to fetch REFerences (fetch according to refSPEC).

Start with an optional +¹, follow by remote:local. remote is the pattern to describe branches on remote. local is the pattern to describe branches at local.

To demostrate in Ruby will look like:

class RefSpec < Struct.new(:remote, :local)
  def self.parse(str)
    remote, local, rest = str.split(":")

    if remote && !rest
      if local
        new(remote, local)
      else
        new(remote, remote)
      end
    else
      nil
    end
  end
end

Refspec Examples

• refs/heads/

+refs/heads/*:refs/remotes/origin/*

• refs/pull/

+refs/heads/*:refs/remotes/origin/*

• refs/tags/

For tags

+refs/tags/*:refs/tags/*

You would use it like this:

git fetch --depth=1 origin +refs/tags/*:refs/tags/*

If you...

• Writing a CI tool
• Working on adding support for forked repositories
• Checking out pull requests locally (GitHub)

Git Refspec offcial document