The ref names and their object names of fetched refs are stored in .git/FETCH_HEAD. This information is left for a later merge operation done by "git merge".
The remote ref that matches <src> is fetched, and if <dst> is not empty string, the local ref that matches it is fast forwarded using <src>. Again, if the optional plus + is used, the local ref is updated even if it does not result in a fast forward update.
Note If the remote branch from which you want to pull is modified in non-linear ways such as being rewound and rebased frequently, then a pull will attempt a merge with an older version of itself, likely conflict, and fail. It is under these conditions that you would want to use the + sign to indicate non-fast-forward updates will be needed. There is currently no easy way to determine or declare that a branch will be made available in a repository with this behavior; the pulling user simply must know this is the expected usage pattern for a branch.
Note You never do your own development on branches that appear on the right hand side of a <refspec> colon on Pull: lines; they are to be updated by git-fetch. If you intend to do development derived from a remote branch B, have a Pull: line to track it (i.e. Pull: B:remote-B), and have a separate branch my-B to do your development on top of it. The latter is created by git branch my-B remote-B (or its equivalent git checkout -b my-B remote-B). Run git fetch to keep track of the progress of the remote side, and when you see something new on the remote branch, merge it into your development branch with git pull . remote-B, while you are on my-B branch. The common Pull: master:origin mapping of a remote master branch to a local origin branch, which is then merged to a local development branch, again typically named master, is made when you run git clone for you to follow this pattern.
Note There is a difference between listing multiple <refspec> directly on git-pull command line and having multiple Pull: <refspec> lines for a <repository> and running git-pull command without any explicit <refspec> parameters. <refspec> listed explicitly on the command line are always merged into the current branch after fetching. In other words, if you list more than one remote refs, you would be making an Octopus. While git-pull run without any explicit <refspec> parameter takes default <refspec>s from Pull: lines, it merges only the first <refspec> found into the current branch, after fetching all the remote refs. This is because making an Octopus from remote refs is rarely done, while keeping track of multiple remote heads in one-go by fetching more than one is often useful. Some short-cut notations are also supported.
URL: one of the above URL format Push: <refspec> Pull: <refspec>Then such a short-hand is specified in place of <repository> without <refspec> parameters on the command line, <refspec> specified on Push: lines or Pull: lines are used for git-push and git-fetch/git-pull, respectively. Multiple Push: and Pull: lines may be specified for additional branch mappings.
Or, equivalently, in the $GIT_DIR/config (note the use of fetch instead of Pull:):
url = <url> push = <refspec> fetch = <refspec>The name of a file in $GIT_DIR/branches directory can be specified as an older notation short-hand; the named file should contain a single line, a URL in one of the above formats, optionally followed by a hash # and the name of remote head (URL fragment notation). $GIT_DIR/branches/<remote> file that stores a <url> without the fragment is equivalent to have this in the corresponding file in the $GIT_DIR/remotes/ directory.
URL: <url> Pull: refs/heads/master:<remote>while having <url>#<head> is equivalent to
URL: <url> Pull: refs/heads/<head>:<remote>