~bzr-pqm/bzr/bzr.dev

Branching a project

===================

Branch URLs

-----------

Before someone else can get a copy of your work, you need to

agree on a transfer technology.

You may decide to make the top level directory of your branch

a network share, an approach familiar to Windows users.

Linux and OS X users might prefer access to be

via SFTP, a secure protocol built-in to most SSH servers.

Bazaar is *very* flexible in this regard with support for

lots of protocols some of which are given below.

  ===========         ======================================================

  Prefix              Description

  ===========         ======================================================

  file://             Access using the standard filesystem (default)

  sftp://             Access using SFTP (most SSH servers provide SFTP).

  bzr://              Fast access using the Bazaar smart server.

  ftp://              Access using passive FTP.

  http://             Read-only access to branches exported by a web server.

  ===========         ======================================================

As indicated above, branches are identified using URLs with the

prefix indicating the transfer technology. If no prefix is given,

normal filenames are assumed. For a complete list of supported

protocols, see the ``urlspec`` online help topic or the

`URL Identifiers <../user-reference/bzr_man.html#url-identifiers>`_

section of the Bazaar User Reference.

A reminder about shared repositories

------------------------------------

Before getting a copy of a branch, have a quick think about

where to put it on your filesystem. For maximum storage

efficiency down the track, it is recommended that branches

be created somewhere under a directory that has been set up

as a shared repository. (See `Feature branches`_ in

n `Organizing your workspace`_ for a commonly used layout.)

For example::

  bzr init-repo my-repo

  cd my-repo

You are now ready to grab a branch from someone else and

hack away.

The branch command

------------------

To get a branch based on an existing branch, use the ``branch`` command.

The syntax is::

  bzr branch URL [directory]

If a directory is not given, one is created based on the last part of

the URL. Here are some examples showing a drive qualified path (M:/) and an

sftp URL respectively::

  bzr branch M:/cool-trunk

  bzr branch sftp://bill@mary-laptop/cool-repo/cool-trunk

This example shows explicitly giving the directory name to use for the

new branch::

  bzr branch /home/mary/cool-repo/cool-trunk cool

Time and space considerations

-----------------------------

Depending on the size of the branch being transferred and the

speed and latency of the network between your computer and the

source branch, this initial transfer might take some time.

Subsequent updates should be much faster as only the

changes are transferred then.

Keep in mind that Bazaar is transferring the

complete history of the branch, not just the latest snapshot.

As a consequence, you can be off the network (or disconnected

from the network share) after ``branch`` completes but you'll

still be able to ``log`` and ``diff`` the history of the

branch as much as you want. Furthermore, these operations

are quick as the history is stored locally.

Note that Bazaar uses smart compression technology to

minimize the amount of disk space required to store version

history. In many cases, the complete history of a project

will take up less disk space than the working copy of

the latest version.

As explained in later chapters, Bazaar also has support for

`lightweight checkouts <#getting-a-lightweight-checkout>`_ 

of a branch, i.e. working trees with

no local storage of history. Of course, disconnected usage

is not available then but that's a tradeoff you can decide

to make if local disk space is really tight for you. Support for

limited lookback into history - *history horizons* - is

currently under development as well.

Viewing branch information

--------------------------

If you wish to see information about a branch including where it came from,

use the ``info`` command. For example::

  bzr info cool

If no branch is given, information on the current branch is displayed.