1
.. This file is in Python ReStructuredText format - it can be formatted
2
.. 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-0.8, 2006-04
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current for bzr 0.0.6pre, July 2005
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*NOTE* For a more current and user-editable version of this
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document, see the wiki at http://bazaar.canonical.com/IntroductionToBzr
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If you are already familiar with decentralized revision control, then
21
please feel free to skip ahead to "Introducing Yourself to Bazaar-NG". If,
22
on the other hand, you are familiar with revision control but not
23
decentralized revision control, then please start at "How DRCS is
24
different." Otherwise, get some coffee or tea, get comfortable and get
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The Purposes of Revision Control
28
================================
30
Odds are that you have worked on some sort of textual data -- the sources
31
to a program, web sites or the config files that Unix system
32
administrators have to deal with in /etc. The chances are also good that
33
you have made some sort of mistake that you deeply regretted. Perhaps you
34
deleted the configuration file for your mailserver or perhaps mauled the
35
source code for a pet project. Whatever happened, you have just deleted
36
important information that you would desperately like to get back. If this
37
has ever happened to you, then you are probably ready for Bazaar-NG.
39
Revision control systems (which I'll henceforth call RCS) such as
40
Bazaar-NG give you the ability to track changes for a directory by turning
41
it into something slightly more complicated than a directory that we call
42
a **branch**. The branch not only stores how the directory looks right
43
now, but also how it looked at various points in the past. Then, when you
44
do something you wish you hadn't, you can restore the directory to the way
45
it looked at some point in the past.
47
Revision control systems give users the ability to save changes to a
48
branch by "committing a **revision**". The revision created is essentially
49
a summary of the changes that were made since the last time the tree was
52
These revisions have other uses as well. For example, one can comment
53
revisions to record what the recent set of changes meant by providing an
54
optional log message. Real life log messages include things like "Fixed
55
the web template to close the table" and "Added sftp suppport. Fixes #595"
57
We keep these logs so that if later there is some sort of problem with
58
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
64
work on the code stored within an RCS, then one needs to connect to the
65
server and "checkout" the code. Doing so gives one a directory in which a
66
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
70
The centralized model can have some drawbacks. A centralized RCS requires
71
that one is able to connect to the server whenever one wants to do version
72
control work. This can be a bit of a problem if your server on some other
73
machine on the internet and you are not. Or, worse yet, you ''are'' on the
74
internet but the server is missing!
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Decentralized Revision Control Systems (which I'll call DRCS after this
77
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
79
the code that is being version controlled. This allows the user to save
80
his changes (**commit**) whenever he wants -- even if he is offline. The
81
user only needs internet access when he wants to access the changes in
82
someone else's branch that are somewhere else.
85
A common requirement that many people have is the need to keep track of
86
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
88
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
95
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
100
that it is based upon. A single revision may have more than one direct
101
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
107
=================================
109
Bazaar-NG installs a single new command, **bzr**. Everything else is a
110
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
114
what. In a decentralized system, that requires an identifier for each
115
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. Setting the email address in the
121
``~/.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. 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/locations.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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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.
24
By branching, Bazaar-NG allows multiple people to cooperate on the evolution of a project, without all needing to work in strict
25
lock-step. Branching can be useful even for a single developer.
27
Bazaar-NG installs a single new command,
28
*bzr*. Everything else is a subcommand of this. You can get
29
some help with ``bzr help``. There will be more in the future.
33
Introducing yourself to bzr
34
===========================
36
One function of a version control system is to keep track of who
37
changed what. In a distributed system that requires an identifier for
38
each author that is globally unique. Most people already have one of
39
these: an email address.
41
[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::
51
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 transmitting 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
56
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.
141
History is by default stored in the .bzr directory of the branch. There
142
will be a facility to store it in a separate repository, which may be
143
remote. We create a new branch by running **bzr init** in an existing
65
History is by default stored in the .bzr directory of the branch.
66
There will be a facility to store it in a separate repository, which
67
may be remote. We create a new branch by running *bzr init* in
68
an existing directory::
151
76
/home/mbp/work/bzr.test/tutorial
158
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As for CVS, there are three classes of file: unknown, ignored, and
159
versioned. The **add** command makes a file versioned: that is, changes
160
to it will be recorded by the system::
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versioned. The *add* command makes a file versioned: that is,
85
changes to it will be recorded by the system::
162
87
% echo 'hello world' > hello.txt
92
% bzr add -v hello.txt
173
If you add the wrong file, simply use **bzr remove** to make it
174
unversioned again. This does not delete the working copy.
179
All history is stored in a branch, which is just an on-disk directory
180
containing control files. By default there is no separate repository or
181
database as used in svn or svk. You can choose to create a repository if
182
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
186
You'll usually refer to branches on your computer's filesystem just by
187
giving the name of the directory containing the branch. bzr also supports
188
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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If you add the wrong file, simply use ``bzr remove`` to make
98
it unversioned again. This does not delete the working copy.
195
101
Reviewing changes
196
102
=================
198
Once you have completed some work, you will want to **commit** it to the
199
version history. It is good to commit fairly often: whenever you get a
200
new feature working, fix a bug, or improve some code or documentation.
201
It's also a good practice to make sure that the code compiles and passes
202
its test suite before committing, to make sure that every revision is a
203
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
205
you permanently record it.
207
Two bzr commands are particularly useful here: **status** and **diff**.
212
The **status** command tells you what changes have been made to the
213
working directory since the last revision::
104
Once you have completed some work, you will want to *commit*
105
it to the version history. It is good to commit fairly often:
106
whenever you get a new feature working, fix a bug, or improve some
107
code or documentation. It's also a good practice to make sure that
108
the code compiles and passes its test suite before committing, to make
109
sure that every revision is a known-good state. You can also review
110
your changes, to make sure you're committing what you intend to, and
111
as a chance to rethink your work before you permanently record it.
113
Two bzr commands are particularly useful here: *status* and
114
*diff*. The *status* command
115
shows a listing with one line per file, indicating whether it has been
116
Added, Deleted, Modified, or Renamed in the current revision. Unknown
117
files are shown as '?'. With the ``--all`` option, the status
118
command also shows unmodified versioned files as '.', and ignored
219
By default **bzr status** hides "boring" files that are either unchanged
220
or ignored. To see them too, use the --all option. The status command
221
can optionally be given the name of some files or directories to check.
226
The **diff** command shows the full text of changes to all files as a
227
standard unified diff. This can be piped through many programs such as
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''patch'', ''diffstat'', ''filterdiff'' and ''colordiff''::
124
The *diff* command shows the full text of changes to all
125
files as a standard unified diff. This can be piped through many
126
programs such as ``patch``, ``diffstat``,
127
``filterdiff`` and ``colordiff``::
231
130
*** added file 'hello.txt'
238
With the ''-r'' option, the tree is compared to an earlier revision, or
239
the differences between two versions are shown::
241
% bzr diff -r 1000.. # everything since r1000
242
% bzr diff -r 1000..1100 # changes from 1000 to 1100
244
The --diff-options option causes bzr to run the external diff program,
245
passing options. For example::
247
% bzr diff --diff-options --side-by-side foo
249
Some projects prefer patches to show a prefix at the start of the path for
250
old and new files. The --prefix option can be used to provide such a prefix.
251
As a shortcut, ``bzr diff -p1`` produces a form that works with the
252
command ``patch -p1``.
136
With the ``-r`` option, the tree is compared to an earlier
139
[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
254
145
Committing changes
255
146
==================
257
When the working tree state is satisfactory, it can be **committed** to
258
the branch, creating a new revision holding a snapshot of that state.
263
The **commit** command takes a message describing the changes in the
264
revision. It also records your userid, the current time and timezone, and
265
the inventory and contents of the tree. The commit message is specified
266
by the ''-m'' or ''--message'' option. You can enter a multi-line commit
267
message; in most shells you can enter this just by leaving the quotes open
268
at the end of the line.
148
When the working tree state is satisfactory, it can be
149
*committed* to the branch, creating a new revision holding a
150
snapshot of that state.
152
The ``commit`` command takes a message describing the changes
153
in the revision. It also records your userid, the current time and
154
timezone, and the inventory and contents of the tree. The commit
155
message is specified by the ``-m`` or ``--message`` option.
156
You can enter a multi-line commit message; in most shells you can
157
enter this just by leaving the quotes open at the end of the line. ::
272
159
% bzr commit -m "added my first file"
274
You can also use the -F option to take the message from a file. Some
275
people like to make notes for a commit message while they work, then
276
review the diff to make sure they did what they said they did. (This file
277
can also be useful when you pick up your work after a break.)
279
Message from an editor
280
======================
282
If you use neither the `-m` nor the `-F` option then bzr will open an
283
editor for you to enter a message. The editor to run is controlled by
284
your `$EDITOR` environment variable or
285
add `editor` to ~/.bazaar/bazaar.conf; `$BZR_EDITOR` will override
286
the above mentioned editor options. If you quit the editor without
287
making any changes, the commit will be cancelled.
292
If you give file or directory names on the commit command line then only
293
the changes to those files will be committed. For example::
295
% bzr commit -m "documentation fix" commit.py
297
By default bzr always commits all changes to the tree, even if run from a
298
subdirectory. To commit from only the current directory down, use::
161
[TODO: commit message interactively, through an editor or from a
164
[TODO: commit only selected files, including renamed/added/deleted
303
169
Removing uncommitted changes
304
170
============================
306
172
If you've made some changes and don't want to keep them, use the
307
**revert** command to go back to the previous head version. It's a good
308
idea to use **bzr diff** first to see what will be removed. By default the
309
revert command reverts the whole tree; if file or directory names are
310
given then only those ones will be affected. **revert** also clears the
311
list of pending merges revisions.
173
``revert`` command to go back to the previous head version. It's a
174
good idea to use ``bzr diff`` first to see what will be removed.
175
By default the revert command reverts the whole tree; if file or
176
directory names are given then only those ones will be affected.
177
revert also clears the list of pending merges revisions.
316
Many source trees contain some files that do not need to be versioned,
317
such as editor backups, object or bytecode files, and built programs. You
318
can simply not add them, but then they'll always crop up as unknown files.
319
You can also tell bzr to ignore these files by adding them to a file
320
called ''.bzrignore'' at the top of the tree.
186
Many source trees contain some files that do not need to be
187
versioned, such as editor backups, object or bytecode files, and built
188
programs. You can simply not add them, but then they'll always crop
189
up as unknown files. You can also tell bzr to ignore these files by
190
adding them to a file called ``.bzrignore`` at the top of the
322
This file contains a list of file wildcards (or "globs"), one per line.
323
Typical contents are like this::
193
This file contains a list of file wildcards (or "globs"), one
194
per line. Typical contents are like this::
330
If a glob contains a slash, it is matched against the whole path from the
331
top of the tree; otherwise it is matched against only the filename. So
332
the previous example ignores files with extension ``.o`` in all
333
subdirectories, but this example ignores only config.h at the top level
334
and HTML files in ``doc/``::
201
If a glob contains a slash, it is matched against the whole path
202
from the top of the tree; otherwise it is matched against only the
203
filename. So the previous example ignores ``*.o`` in all
204
subdirectories, but this example ignores only config.h at the top
205
level and HTML files in ``doc/``::
339
To get a list of which files are ignored and what pattern they matched,
340
use ''bzr ignored''::
210
To get a list of which files are ignored and what pattern they matched, use ``bzr ignored``::
346
It is OK to have either an ignore pattern match a versioned file, or to
347
add an ignored file. Ignore patterns have no effect on versioned files;
348
they only determine whether unversioned files are reported as unknown or
351
The ''.bzrignore'' file should normally be versioned, so that new copies
352
of the branch see the same patterns::
216
It is OK to have an ignore pattern match a versioned file, or to
217
add an ignored file. Ignore patterns have no effect on versioned
218
files; they only determine whether unversioned files are reported as
221
The ``.bzrignore`` file should normally be versioned, so that new
222
copies of the branch see the same patterns::
354
224
% bzr add .bzrignore
355
225
% bzr commit -m "Add ignore patterns"
364
The **bzr log** command shows a list of previous revisions. The **bzr log
365
--forward** command does the same in chronological order to get most
366
recent revisions printed at last.
368
As with bzr diff, bzr log supports the -r argument::
370
% bzr log -r 1000.. # Revision 1000 and everything after it
371
% bzr log -r ..1000 # Everything up to and including r1000
372
% bzr log -r 1000..1100 # changes from 1000 to 1100
373
% bzr log -r 1000 # The changes in only revision 1000
234
The ``log`` command shows a list of previous revisions.
376
237
Branch statistics
377
238
=================
379
The **bzr info** command shows some summary information about the working
380
tree and the branch history.
240
The ``bzr info`` command shows some summary information about
241
the working tree and the branch history.
383
244
Versioning directories
384
245
======================
386
bzr versions files and directories in a way that can keep track of renames
387
and intelligently merge them::
247
bzr versions files and directories in a way that can keep track of
248
renames and intelligently merge them::
390
251
% echo 'int main() {}' > src/simple.c
256
% bzr add src/simple.c
400
262
Deleting and removing files
401
263
===========================
403
You can delete files or directories by just deleting them from the working
404
directory. This is a bit different to CVS, which requires that you also
407
**bzr remove** makes the file un-versioned, but does not delete
408
the working copy. This is useful when you add the wrong file, or decide
409
that a file should actually not be versioned.
265
You can delete files or directories by just deleting them from the
266
working directory. This is a bit different to CVS, which requires
267
that you also do *cvs remove*.
269
*bzr remove* makes the file un-versioned, but does not
270
delete the working copy. This is useful when you add the wrong file,
271
or decide that a file should actually not be versioned. ::
414
274
% bzr remove -v hello.txt
424
If you remove the wrong file by accident, you can use **bzr revert** to
431
Often rather than starting your own project, you will want to submit a
432
change to an existing project. You can get a copy of an existing branch
433
by copying its directory, expanding a tarball, or by a remote copy using
434
something like rsync. You can also use bzr to fetch a copy. Because this
435
new copy is potentially a new branch, the command is called *branch*::
285
Often rather than starting your own project, you will want to
286
submit a change to an existing project. You can get a copy of an
287
existing branch by copying its directory, expanding a tarball, or by a
288
remote copy using something like rsync. You can also use bzr to fetch
289
a copy. Because this new copy is potentially a new branch, the
290
command is called *branch*::
437
% bzr branch http://bazaar-ng.org/bzr/bzr.dev
292
% bzr branch http://bazaar-ng.org/bzr/bzr.dev
440
This copies down the complete history of this branch, so we can do all
441
operations on it locally: log, annotate, making and merging branches.
442
There will be an option to get only part of the history if you wish.
295
This copies down the complete history of this branch, so we can
296
do all operations on it locally: log, annotate, making and merging
297
branches. There will be an option to get only part of the history if
444
302
Following upstream changes
445
303
==========================
447
You can stay up-to-date with the parent branch by "pulling" in their
305
You can stay up-to-date with the parent branch by *pulling*
452
After this change, the local directory will be a mirror of the source. This
453
includes the ''revision-history'' - which is a list of the commits done in
454
this branch, rather than merged from other branches.
456
This command only works if your local (destination) branch is either an
457
older copy of the parent branch with no new commits of its own, or if the
458
most recent commit in your local branch has been merged into the parent
461
Merging from related branches
462
=============================
464
If two branches have diverged (both have unique changes) then **bzr
465
merge** is the appropriate command to use. Merge will automatically
466
calculate the changes that exist in the branch you're merging from that
467
are not in your branch and attempt to apply them in your branch.
474
If there is a conflict during a merge, 3 files with the same basename are
475
created. The filename of the common base is appended with .BASE, the
476
filename of the file containing your changes is appended .THIS and the
477
filename with the changes from the other tree is appended .OTHER.
478
Using a program such as kdiff3, you can now comfortably merge them into
479
one file. To commit you have to rename it to the original basename and
480
delete the other two files. As long as there exist files with .BASE, .THIS
481
or .OTHER the commit command will complain.
483
[**TODO**: explain conflict markers within files]
486
Publishing your branch
487
======================
489
You don't need a special server to publish a bzr branch, just a normal web
490
server. Just mirror the files to your server, including the .bzr
491
directory. One can push a branch (or the changes for a branch) by one of
492
the following three methods:
494
* Rsync: rsync -avrz LOCALBRANCH servername.com/this/directory/here
496
(or any other tool for publishing a directory to a web site.)
498
* bzr push sftp://servername.com/this/directory/here
500
(The directory that must already exist)
502
* The rspush plugin that comes with BzrTools
310
This only works if your local branch includes only changes from the
311
parent branch. Otherwise, the branches are said to have *diverged*,
312
and they must be merged instead.
added
removed
tutorial.txt
