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.. This file is in Python ReStructuredText format - it can be formatted
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.. into HTML or text. In the future we plan to extract the example commands
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.. and automatically test them.
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.. This text was previously on the wiki at
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.. http://bazaar.canonical.com/IntroductionToBzr
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.. but has been moved into the source tree so it can be kept in sync with
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.. the source and possibly automatically checked.
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current for bzr 0.0.6pre, July 2005
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*Note:* This tutorial is a work in
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progress, and describes code that is itself still evolving.
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If you have comments on either the design or the tutorial,
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please send them to the bazaar-ng@lists.canonical.com mailing list.
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Current for bzr-0.8, 2006-04
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Bazaar-NG is a version control tool. It manages trees of files and subdirectories. In particular, it records *revisions* of trees, representing their state at a particular point in time, and information about those revisions and their relationships. Recording and retrieving tree revisions is useful in several ways if you are writing software or documents or doing similar creative work.
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* Keeping previous revisions lets you go back if you make a mistake or want to check your work. It acts as a high-level unlimited undo.
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* By recording comments on every revision, you produce an annotated history of the project, describing what, who, why, and when.
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* Using a version control tool can be an aid to thinking about a project: getting to a stable state at regular intervals and then writing a description of what you did is an easy way to stay organized and on track.
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Bazaar-NG remembers the *ancestry* of a revision: the previous revisions that it is based upon. A single revision may have more than one direct descendant, each with different changes, representing a divergence in the evolution of the tree.
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By branching, Bazaar-NG allows multiple people to cooperate on the evolution of a project, without all needing to work in strict
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lock-step. Branching can be useful even for a single developer.
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Bazaar-NG installs a single new command,
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*bzr*. Everything else is a subcommand of this. You can get
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some help with ``bzr help``. There will be more in the future.
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Introducing yourself to bzr
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===========================
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One function of a version control system is to keep track of who
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changed what. In a distributed system that requires an identifier for
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each author that is globally unique. Most people already have one of
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these: an email address.
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[after 0.0.4] To tell bzr which email address to use, put it in the file
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``$HOME/.bzr.conf/email``, or the environment variable ``$BZREMAIL``.
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If neither of these are set, bzr will use the ``$EMAIL``
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variable, or use your username and hostname.
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To check this has taken effect, or if you forget your own name, use
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the ``whoami`` ("who am i?") command::
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Some people want to avoid sharing their email address so as not to
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get spam. bzr will never
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disclose your email address unless you tell it to by publishing an
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archive or transmiting a changeset. It's recommended that you do use
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a real address, so that people can contact you about your work, but
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it's not required. You can use an address which is obfuscated, which
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bounces, or which goes through an anti-spam service such as spamgourmet.com.
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If you are already familiar with decentralized revision control, then
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please feel free to skip ahead to "Introducing Yourself to Bazaar-NG". If,
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on the other hand, you are familiar with revision control but not
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decentralized revision control, then please start at "How DRCS is
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different." Otherwise, get some coffee or tea, get comfortable and get
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The Purposes of Revision Control
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================================
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Odds are that you have worked on some sort of textual data -- the sources
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to a program, web sites or the config files that Unix system
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administrators have to deal with in /etc. The chances are also good that
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you have made some sort of mistake that you deeply regretted. Perhaps you
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deleted the configuration file for your mailserver or perhaps mauled the
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source code for a pet project. Whatever happened, you have just deleted
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important information that you would desperately like to get back. If this
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has ever happened to you, then you are probably ready for Bazaar-NG.
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Revision control systems (which I'll henceforth call RCS) such as
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Bazaar-NG give you the ability to track changes for a directory by turning
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it into something slightly more complicated than a directory that we call
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a **branch**. The branch not only stores how the directory looks right
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now, but also how it looked at various points in the past. Then, when you
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do something you wish you hadn't, you can restore the directory to the way
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it looked at some point in the past.
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Revision control systems give users the ability to save changes to a
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branch by "committing a **revision**". The revision created is essentially
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a summary of the changes that were made since the last time the tree was
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These revisions have other uses as well. For example, one can comment
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revisions to record what the recent set of changes meant by providing an
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optional log message. Real life log messages include things like "Fixed
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the web template to close the table" and "Added sftp suppport. Fixes #595"
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We keep these logs so that if later there is some sort of problem with
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sftp, we can figure out when the problem probably happened.
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Many Revision Control Systems (RCS) are stored on servers. If one wants to
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work on the code stored within an RCS, then one needs to connect to the
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server and "checkout" the code. Doing so gives one a directory in which a
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person can make changes and then commit. The RCS client then connects to
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the RCS server and stores the changes. This method is known as the
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The centralized model can have some drawbacks. A centralized RCS requires
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that one is able to connect to the server whenever one wants to do version
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control work. This can be a bit of a problem if your server on some other
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machine on the internet and you are not. Or, worse yet, you ''are'' on the
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internet but the server is missing!
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Decentralized Revision Control Systems (which I'll call DRCS after this
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point) deal with this problem by keeping branches on the same machine as
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the client. In Bazaar-NG's case, the branch is kept in the same place as
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the code that is being version controlled. This allows the user to save
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his changes (**commit**) whenever he wants -- even if he is offline. The
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user only needs internet access when he wants to access the changes in
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someone else's branch that are somewhere else.
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A common requirement that many people have is the need to keep track of
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the changes for a directory such as file and subdirectory changes.
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Performing this tracking by hand is a awkward process that over time
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becomes unwieldy. That is, until one considers version control tools such
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as Bazaar-NG. These tools automate the process of storing data by creating
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a **revision** of the directory tree whenever the user asks.
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Revision control software such as Bazaar-NG can do much more than just
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storage and performing undo. For example, with Bazaar-NG developer can
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take the modifications in one branch of software and apply them to
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another, related, branch -- even if those changes exist in a branch owned
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by somebody else. This allows developers to cooperate without giving write
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Bazaar-NG remembers the ''ancestry'' of a revision: the previous revisions
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that it is based upon. A single revision may have more than one direct
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descendant, each with different changes, representing a divergence in the
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evolution of the tree. By branching, Bazaar-NG allows multiple people to
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cooperate on the evolution of a project, without all needing to work in
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strict lock-step. Branching can be useful even for a single developer.
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Introducing yourself to Bazaar-NG
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=================================
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Bazaar-NG installs a single new command, **bzr**. Everything else is a
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subcommand of this. You can get some help with `bzr help`. There will be
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One function of a version control system is to keep track of who changed
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what. In a decentralized system, that requires an identifier for each
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author that is globally unique. Most people already have one of these: an
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email address. Bzr is smart enough to automatically generate an email
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address by looking up your username and hostname. If you don't like the
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guess that Bazaar-NG makes, then three options exist:
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1. (**Bazaar-NG 0.6 and later**). Setting the email address in the
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``~/.bazaar/bazaar.conf`` by adding the following lines. Please note that
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``[DEFAULT]`` is case sensitive::
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email= Your Name <email@isp.com>
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1. (**Bazaar-NG 0.6 and later**) Override the previous setting on a
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branch by branch basis by creating a branch section in
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``~/.bazaar/branches.conf`` by adding the following lines::
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[/the/directory/to/the/branch]
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email=Your Name <email@isp.com>
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1. Overriding the two previous options by setting the global environment
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variable ``$BZREMAIL`` or ``$EMAIL`` (``$BZREMAIL`` will take precedence)
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to your full email address.
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History is by default stored in the .bzr directory of the branch.
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There will be a facility to store it in a separate repository, which
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may be remote. We create a new branch by running *bzr init* in
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an existing directory::
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History is by default stored in the .bzr directory of the branch. There
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will be a facility to store it in a separate repository, which may be
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remote. We create a new branch by running **bzr init** in an existing
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/home/mbp/work/bzr.test/tutorial
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As for CVS, there are three classes of file: unknown, ignored, and
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versioned. The *add* command makes a file versioned: that is,
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changes to it will be recorded by the system::
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versioned. The **add** command makes a file versioned: that is, changes
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to it will be recorded by the system::
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% echo 'hello world' > hello.txt
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% bzr add -v hello.txt
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If you add the wrong file, simply use ``bzr remove`` to make
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it unversioned again. This does not delete the working copy.
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If you add the wrong file, simply use **bzr remove** to make it
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unversioned again. This does not delete the working copy.
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All history is stored in a branch, which is just an on-disk directory
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containing control files. By default there is no separate repository or
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database as used in svn or svk. You can choose to create a repository if
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you want to (see the **bzr init-repo** command). You may wish to do this
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if you have very large branches, or many branches of a moderate sized
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You'll usually refer to branches on your computer's filesystem just by
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giving the name of the directory containing the branch. bzr also supports
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accessing branches over http, for example::
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% bzr log http://bazaar-ng.org/bzr/bzr.dev/
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By installing bzr plugins you can also access branches over the sftp or
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Reviewing changes
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196
=================
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Once you have completed some work, you will want to *commit*
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it to the version history. It is good to commit fairly often:
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whenever you get a new feature working, fix a bug, or improve some
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code or documentation. It's also a good practice to make sure that
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the code compiles and passes its test suite before committing, to make
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sure that every revision is a known-good state. You can also review
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your changes, to make sure you're committing what you intend to, and
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as a chance to rethink your work before you permanently record it.
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Two bzr commands are particularly useful here: *status* and
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*diff*. The *status* command
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shows a listing with one line per file, indicating whether it has been
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Added, Deleted, Modified, or Renamed in the current revision. Unknown
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files are shown as '?'. With the ``--all`` option, the status
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command also shows unmodified versioned files as '.', and ignored
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Once you have completed some work, you will want to **commit** it to the
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version history. It is good to commit fairly often: whenever you get a
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new feature working, fix a bug, or improve some code or documentation.
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It's also a good practice to make sure that the code compiles and passes
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its test suite before committing, to make sure that every revision is a
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known-good state. You can also review your changes, to make sure you're
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committing what you intend to, and as a chance to rethink your work before
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you permanently record it.
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Two bzr commands are particularly useful here: **status** and **diff**.
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The **status** command tells you what changes have been made to the
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working directory since the last revision::
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The *diff* command shows the full text of changes to all
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files as a standard unified diff. This can be piped through many
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programs such as ``patch``, ``diffstat``,
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``filterdiff`` and ``colordiff``::
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By default **bzr status** hides "boring" files that are either unchanged
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or ignored. To see them too, use the --all option. The status command
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can optionally be given the name of some files or directories to check.
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The **diff** command shows the full text of changes to all files as a
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standard unified diff. This can be piped through many programs such as
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''patch'', ''diffstat'', ''filterdiff'' and ''colordiff''::
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*** added file 'hello.txt'
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With the ``-r`` option, the tree is compared to an earlier
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[TODO: options to run external diff; to get context diff or other
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formats; to diff only selected files; to compare two historical
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With the ''-r'' option, the tree is compared to an earlier revision, or
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the differences between two versions are shown::
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% bzr diff -r 1000.. # everything since r1000
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% bzr diff -r 1000..1100 # changes from 1000 to 1100
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The --diff-options option causes bzr to run the external diff program,
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passing options. For example::
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% bzr diff --diff-options --side-by-side foo
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Committing changes
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250
==================
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When the working tree state is satisfactory, it can be
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*committed* to the branch, creating a new revision holding a
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snapshot of that state.
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The ``commit`` command takes a message describing the changes
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in the revision. It also records your userid, the current time and
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timezone, and the inventory and contents of the tree. The commit
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message is specified by the ``-m`` or ``--message`` option.
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You can enter a multi-line commit message; in most shells you can
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enter this just by leaving the quotes open at the end of the line. ::
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When the working tree state is satisfactory, it can be **committed** to
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the branch, creating a new revision holding a snapshot of that state.
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The **commit** command takes a message describing the changes in the
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revision. It also records your userid, the current time and timezone, and
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the inventory and contents of the tree. The commit message is specified
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by the ''-m'' or ''--message'' option. You can enter a multi-line commit
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message; in most shells you can enter this just by leaving the quotes open
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at the end of the line.
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% bzr commit -m "added my first file"
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[TODO: commit message interactively, through an editor or from a
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[TODO: commit only selected files, including renamed/added/deleted
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You can also use the -F option to take the message from a file. Some
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people like to make notes for a commit message while they work, then
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review the diff to make sure they did what they said they did. (This file
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can also be useful when you pick up your work after a break.)
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Message from an editor
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======================
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If you use neither the `-m` nor the `-F` option then bzr will open an
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editor for you to enter a message. The editor to run is controlled by
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your `$EDITOR` environment variable or (Post Bazaar-NG 0.6) email setting
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in . If you quit the editor without making any changes, the commit will
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If you give file or directory names on the commit command line then only
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the changes to those files will be committed. For example::
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% bzr commit -m "documentation fix" commit.py
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By default bzr always commits all changes to the tree, even if run from a
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subdirectory. To commit from only the current directory down, use::
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Removing uncommitted changes
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============================
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If you've made some changes and don't want to keep them, use the
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``revert`` command to go back to the previous head version. It's a
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good idea to use ``bzr diff`` first to see what will be removed.
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By default the revert command reverts the whole tree; if file or
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directory names are given then only those ones will be affected.
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revert also clears the list of pending merges revisions.
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**revert** command to go back to the previous head version. It's a good
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idea to use **bzr diff** first to see what will be removed. By default the
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revert command reverts the whole tree; if file or directory names are
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given then only those ones will be affected. **revert** also clears the
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list of pending merges revisions.
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Many source trees contain some files that do not need to be
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versioned, such as editor backups, object or bytecode files, and built
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programs. You can simply not add them, but then they'll always crop
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up as unknown files. You can also tell bzr to ignore these files by
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adding them to a file called ``.bzrignore`` at the top of the
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Many source trees contain some files that do not need to be versioned,
311
such as editor backups, object or bytecode files, and built programs. You
312
can simply not add them, but then they'll always crop up as unknown files.
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You can also tell bzr to ignore these files by adding them to a file
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called ''.bzrignore'' at the top of the tree.
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This file contains a list of file wildcards (or "globs"), one
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per line. Typical contents are like this::
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This file contains a list of file wildcards (or "globs"), one per line.
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Typical contents are like this::
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If a glob contains a slash, it is matched against the whole path
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from the top of the tree; otherwise it is matched against only the
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filename. So the previous example ignores ``*.o`` in all
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subdirectories, but this example ignores only config.h at the top
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level and HTML files in ``doc/``::
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If a glob contains a slash, it is matched against the whole path from the
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top of the tree; otherwise it is matched against only the filename. So
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the previous example ignores files with extension ``.o`` in all
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subdirectories, but this example ignores only config.h at the top level
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and HTML files in ``doc/``::
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To get a list of which files are ignored and what pattern they matched, use ``bzr ignored``::
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To get a list of which files are ignored and what pattern they matched,
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use ''bzr ignored''::
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It is OK to have an ignore pattern match a versioned file, or to
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add an ignored file. Ignore patterns have no effect on versioned
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files; they only determine whether unversioned files are reported as
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The ``.bzrignore`` file should normally be versioned, so that new
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copies of the branch see the same patterns::
340
It is OK to have either an ignore pattern match a versioned file, or to
341
add an ignored file. Ignore patterns have no effect on versioned files;
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they only determine whether unversioned files are reported as unknown or
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The ''.bzrignore'' file should normally be versioned, so that new copies
346
of the branch see the same patterns::
227
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% bzr add .bzrignore
228
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% bzr commit -m "Add ignore patterns"
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If you remove the wrong file by accident, you can use **bzr revert** to
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Often rather than starting your own project, you will want to
289
submit a change to an existing project. You can get a copy of an
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existing branch by copying its directory, expanding a tarball, or by a
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remote copy using something like rsync. You can also use bzr to fetch
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a copy. Because this new copy is potentially a new branch, the
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command is called *branch*::
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% bzr branch http://bazaar-ng.org/bzr/main ./bzr-main
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This copies down the complete history of this branch, so we can
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do all operations on it locally: log, annotate, making and merging
300
branches. There will be an option to get only part of the history if
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Often rather than starting your own project, you will want to submit a
424
change to an existing project. You can get a copy of an existing branch
425
by copying its directory, expanding a tarball, or by a remote copy using
426
something like rsync. You can also use bzr to fetch a copy. Because this
427
new copy is potentially a new branch, the command is called *branch*::
429
% bzr branch http://bazaar-ng.org/bzr/bzr.dev
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This copies down the complete history of this branch, so we can do all
433
operations on it locally: log, annotate, making and merging branches.
434
There will be an option to get only part of the history if you wish.
305
436
Following upstream changes
306
437
==========================
308
You can stay up-to-date with the parent branch by *pulling*
439
You can stay up-to-date with the parent branch by "pulling" in their
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This only works if the local branch if your branch includes only
314
changes from the parent branch. Otherwise, the branches are said to
315
have *diverged*, and they must be merged instead.
444
After this change, the local directory will be a mirror of the source. This
445
includes the ''revision-history'' - which is a list of the commits done in
446
this branch, rather than merged from other branches.
448
This command only works if your local (destination) branch is either an
449
older copy of the parent branch with no new commits of its own, or if the
450
most recent commit in your local branch has been merged into the parent
453
Merging from related branches
454
=============================
456
If two branches have diverged (both have unique changes) then **bzr
457
merge** is the appropriate command to use. Merge will automatically
458
calculate the changes that exist in the branch you're merging from that
459
are not in your branch and attempt to apply them in your branch.
466
If there is a conflict during a merge, 3 files with the same basename are
467
created. The filename of the common base is appended with .BASE, the
468
filename of the file containing your changes is appended .THIS and the
469
filename with the changes from the other tree is appended .OTHER.
470
Using a program such as kdiff3, you can now comfortably merge them into
471
one file. To commit you have to rename it to the original basename and
472
delete the other two files. As long as there exist files with .BASE, .THIS
473
or .OTHER the commit command will complain.
475
[**TODO**: explain conflict markers within files]
478
Publishing your branch
479
======================
481
You don't need a special server to publish a bzr branch, just a normal web
482
server. Just mirror the files to your server, including the .bzr
483
directory. One can push a branch (or the changes for a branch) by one of
484
the following three methods:
486
* Rsync: rsync -avrz LOCALBRANCH servername.com/this/directory/here
488
(or any other tool for publishing a directory to a web site.)
490
* bzr push sftp://servername.com/this/directory/here
492
(The directory that must already exist)
494
* The push plugin that comes with BzrTools
added
removed
tutorial.txt
