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. Unix 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:// Access to branches exported by a web server.
https:// Encrypted 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 section of the Bazaar User Reference.

URLs are normally resolved relative to the root directory of the server, so ftp://example.com/repo/foo means the /repo/foo directory of that host. (We say ‘normally’ because some server software like Apache can be configured to remap URLs arbitrarily, in which case you’ll need to look at the server configuration to find out which URL corresponds to which directory.)

To address a path relative to your home directory on the server, use a tilde like so: sftp://example.com/~/public_html should map to public_html within your home directory.

Note

Access over HTTP or HTTPS is read-only by default. See Pushing over the HTTP smart server for details on configuring read-write access.

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 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 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.

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