hgbook

annotate en/tour-basic.tex @ 281:a880d07f2d29

find changesets by author, revision, files, or words in the commit message
Fix repository paths of data/index files in filelog diagram.

Data/index files are stored in the repository at .hg/store/data, not .hg/data.
Modify the filelog diagram to reflect this.
author Arun Thomas <arun.thomas@gmail.com>
date Mon Dec 17 23:16:59 2007 -0500 (2007-12-17)
parents 6a847f7902a7
children a168daed199b cd595464fea9
rev   line source
bos@95 1 \chapter{A tour of Mercurial: the basics}
bos@95 2 \label{chap:tour-basic}
bos@84 3
bos@84 4 \section{Installing Mercurial on your system}
bos@84 5 \label{sec:tour:install}
bos@84 6
bos@85 7 Prebuilt binary packages of Mercurial are available for every popular
bos@85 8 operating system. These make it easy to start using Mercurial on your
bos@85 9 computer immediately.
bos@85 10
bos@84 11 \subsection{Linux}
bos@84 12
bos@84 13 Because each Linux distribution has its own packaging tools, policies,
bos@84 14 and rate of development, it's difficult to give a comprehensive set of
bos@85 15 instructions on how to install Mercurial binaries. The version of
bos@85 16 Mercurial that you will end up with can vary depending on how active
bos@85 17 the person is who maintains the package for your distribution.
bos@84 18
bos@84 19 To keep things simple, I will focus on installing Mercurial from the
bos@84 20 command line under the most popular Linux distributions. Most of
bos@84 21 these distributions provide graphical package managers that will let
bos@84 22 you install Mercurial with a single click; the package name to look
bos@84 23 for is \texttt{mercurial}.
bos@84 24
bos@85 25 \begin{itemize}
bos@85 26 \item[Debian]
bos@85 27 \begin{codesample4}
bos@85 28 apt-get install mercurial
bos@85 29 \end{codesample4}
bos@84 30
bos@85 31 \item[Fedora Core]
bos@85 32 \begin{codesample4}
bos@85 33 yum install mercurial
bos@85 34 \end{codesample4}
bos@84 35
bos@85 36 \item[Gentoo]
bos@85 37 \begin{codesample4}
bos@85 38 emerge mercurial
bos@85 39 \end{codesample4}
bos@84 40
bos@85 41 \item[OpenSUSE]
bos@85 42 \begin{codesample4}
bos@85 43 yum install mercurial
bos@85 44 \end{codesample4}
bos@84 45
bos@262 46 \item[Ubuntu] Ubuntu's Mercurial package is based on Debian's. To
bos@262 47 install it, run the following command.
bos@262 48 \begin{codesample4}
bos@262 49 apt-get install mercurial
bos@262 50 \end{codesample4}
bos@262 51 The Ubuntu package for Mercurial tends to lag behind the Debian
bos@262 52 version by a considerable time margin (at the time of writing, seven
bos@262 53 months), which in some cases will mean that on Ubuntu, you may run
bos@262 54 into problems that have since been fixed in the Debian package.
bos@85 55 \end{itemize}
bos@84 56
arne@264 57 \subsection{Solaris}
arne@264 58
arne@264 59 XXX.
arne@264 60
bos@84 61 \subsection{Mac OS X}
bos@84 62
bos@84 63 Lee Cantey publishes an installer of Mercurial for Mac OS~X at
bos@84 64 \url{http://mercurial.berkwood.com}. This package works on both
bos@85 65 Intel-~and Power-based Macs. Before you can use it, you must install
bos@85 66 a compatible version of Universal MacPython~\cite{web:macpython}. This
bos@85 67 is easy to do; simply follow the instructions on Lee's site.
bos@84 68
bos@84 69 \subsection{Windows}
bos@84 70
arne@264 71 Lee Cantey also publishes an installer of Mercurial for Windows at
bos@84 72 \url{http://mercurial.berkwood.com}. This package has no external
bos@84 73 dependencies; it ``just works''.
bos@84 74
bos@84 75 \begin{note}
bos@84 76 The Windows version of Mercurial does not automatically convert line
bos@84 77 endings between Windows and Unix styles. If you want to share work
bos@84 78 with Unix users, you must do a little additional configuration
bos@84 79 work. XXX Flesh this out.
bos@84 80 \end{note}
bos@84 81
bos@87 82 \section{Getting started}
bos@87 83
bos@87 84 To begin, we'll use the \hgcmd{version} command to find out whether
bos@87 85 Mercurial is actually installed properly. The actual version
bos@87 86 information that it prints isn't so important; it's whether it prints
bos@87 87 anything at all that we care about.
bos@87 88 \interaction{tour.version}
bos@87 89
bos@87 90 \subsection{Built-in help}
bos@87 91
steve@158 92 Mercurial provides a built-in help system. This is invaluable for those
bos@87 93 times when you find yourself stuck trying to remember how to run a
bos@87 94 command. If you are completely stuck, simply run \hgcmd{help}; it
bos@87 95 will print a brief list of commands, along with a description of what
bos@87 96 each does. If you ask for help on a specific command (as below), it
bos@87 97 prints more detailed information.
bos@87 98 \interaction{tour.help}
bos@87 99 For a more impressive level of detail (which you won't usually need)
bos@87 100 run \hgcmdargs{help}{\hggopt{-v}}. The \hggopt{-v} option is short
bos@87 101 for \hggopt{--verbose}, and tells Mercurial to print more information
bos@87 102 than it usually would.
bos@87 103
bos@87 104 \section{Working with a repository}
bos@87 105
bos@87 106 In Mercurial, everything happens inside a \emph{repository}. The
bos@87 107 repository for a project contains all of the files that ``belong to''
bos@87 108 that project, along with a historical record of the project's files.
bos@87 109
bos@87 110 There's nothing particularly magical about a repository; it is simply
bos@87 111 a directory tree in your filesystem that Mercurial treats as special.
steve@158 112 You can rename or delete a repository any time you like, using either the
bos@87 113 command line or your file browser.
bos@87 114
bos@88 115 \subsection{Making a local copy of a repository}
bos@87 116
bos@87 117 \emph{Copying} a repository is just a little bit special. While you
bos@87 118 could use a normal file copying command to make a copy of a
bos@87 119 repository, it's best to use a built-in command that Mercurial
bos@87 120 provides. This command is called \hgcmd{clone}, because it creates an
bos@87 121 identical copy of an existing repository.
bos@87 122 \interaction{tour.clone}
bos@87 123 If our clone succeeded, we should now have a local directory called
bos@87 124 \dirname{hello}. This directory will contain some files.
bos@87 125 \interaction{tour.ls}
bos@87 126 These files have the same contents and history in our repository as
bos@87 127 they do in the repository we cloned.
bos@87 128
bos@87 129 Every Mercurial repository is complete, self-contained, and
bos@87 130 independent. It contains its own private copy of a project's files
bos@87 131 and history. A cloned repository remembers the location of the
bos@87 132 repository it was cloned from, but it does not communicate with that
bos@87 133 repository, or any other, unless you tell it to.
bos@87 134
bos@87 135 What this means for now is that we're free to experiment with our
bos@87 136 repository, safe in the knowledge that it's a private ``sandbox'' that
bos@87 137 won't affect anyone else.
bos@85 138
bos@88 139 \subsection{What's in a repository?}
bos@88 140
bos@88 141 When we take a more detailed look inside a repository, we can see that
bos@88 142 it contains a directory named \dirname{.hg}. This is where Mercurial
bos@88 143 keeps all of its metadata for the repository.
bos@88 144 \interaction{tour.ls-a}
bos@88 145
bos@88 146 The contents of the \dirname{.hg} directory and its subdirectories are
bos@88 147 private to Mercurial. Every other file and directory in the
bos@88 148 repository is yours to do with as you please.
bos@88 149
bos@88 150 To introduce a little terminology, the \dirname{.hg} directory is the
bos@88 151 ``real'' repository, and all of the files and directories that coexist
bos@91 152 with it are said to live in the \emph{working directory}. An easy way
bos@91 153 to remember the distinction is that the \emph{repository} contains the
bos@88 154 \emph{history} of your project, while the \emph{working directory}
bos@88 155 contains a \emph{snapshot} of your project at a particular point in
bos@88 156 history.
bos@88 157
bos@88 158 \section{A tour through history}
bos@88 159
bos@88 160 One of the first things we might want to do with a new, unfamiliar
bos@88 161 repository is understand its history. The \hgcmd{log} command gives
bos@88 162 us a view of history.
bos@88 163 \interaction{tour.log}
bos@88 164 By default, this command prints a brief paragraph of output for each
bos@88 165 change to the project that was recorded. In Mercurial terminology, we
bos@88 166 call each of these recorded events a \emph{changeset}, because it can
bos@88 167 contain a record of changes to several files.
bos@88 168
bos@88 169 The fields in a record of output from \hgcmd{log} are as follows.
bos@88 170 \begin{itemize}
bos@88 171 \item[\texttt{changeset}] This field has the format of a number,
bos@88 172 followed by a colon, followed by a hexadecimal string. These are
bos@88 173 \emph{identifiers} for the changeset. There are two identifiers
bos@88 174 because the number is shorter and easier to type than the hex
bos@88 175 string.
bos@88 176 \item[\texttt{user}] The identity of the person who created the
bos@88 177 changeset. This is a free-form field, but it most often contains a
bos@88 178 person's name and email address.
bos@88 179 \item[\texttt{date}] The date and time on which the changeset was
steve@158 180 created, and the timezone in which it was created. (The date and
bos@88 181 time are local to that timezone; they display what time and date it
bos@88 182 was for the person who created the changeset.)
bos@88 183 \item[\texttt{summary}] The first line of the text message that the
bos@88 184 creator of the changeset entered to describe the changeset.
bos@88 185 \end{itemize}
bos@88 186 The default output printed by \hgcmd{log} is purely a summary; it is
bos@88 187 missing a lot of detail.
bos@88 188
bos@99 189 Figure~\ref{fig:tour-basic:history} provides a graphical representation of
bos@97 190 the history of the \dirname{hello} repository, to make it a little
bos@97 191 easier to see which direction history is ``flowing'' in. We'll be
bos@97 192 returning to this figure several times in this chapter and the chapter
bos@97 193 that follows.
bos@97 194
bos@96 195 \begin{figure}[ht]
bos@96 196 \centering
bos@96 197 \grafix{tour-history}
bos@96 198 \caption{Graphical history of the \dirname{hello} repository}
bos@99 199 \label{fig:tour-basic:history}
bos@96 200 \end{figure}
bos@96 201
bos@97 202 \subsection{Changesets, revisions, and talking to other
bos@97 203 people}
bos@97 204
bos@97 205 As English is a notoriously sloppy language, and computer science has
bos@99 206 a hallowed history of terminological confusion (why use one term when
bos@99 207 four will do?), revision control has a variety of words and phrases
bos@99 208 that mean the same thing. If you are talking about Mercurial history
bos@99 209 with other people, you will find that the word ``changeset'' is often
bos@99 210 compressed to ``change'' or (when written) ``cset'', and sometimes a
bos@99 211 changeset is referred to as a ``revision'' or a ``rev''.
bos@88 212
bos@88 213 While it doesn't matter what \emph{word} you use to refer to the
bos@88 214 concept of ``a~changeset'', the \emph{identifier} that you use to
bos@88 215 refer to ``a~\emph{specific} changeset'' is of great importance.
bos@88 216 Recall that the \texttt{changeset} field in the output from
bos@88 217 \hgcmd{log} identifies a changeset using both a number and a
bos@97 218 hexadecimal string.
bos@97 219 \begin{itemize}
bos@97 220 \item The revision number is \emph{only valid in that repository},
bos@97 221 \item while the hex string is the \emph{permanent, unchanging
bos@97 222 identifier} that will always identify that exact changeset in
bos@97 223 \emph{every} copy of the repository.
bos@97 224 \end{itemize}
bos@88 225 This distinction is important. If you send someone an email talking
bos@88 226 about ``revision~33'', there's a high likelihood that their
bos@88 227 revision~33 will \emph{not be the same} as yours. The reason for this
bos@88 228 is that a revision number depends on the order in which changes
bos@88 229 arrived in a repository, and there is no guarantee that the same
bos@88 230 changes will happen in the same order in different repositories.
bos@88 231 Three changes $a,b,c$ can easily appear in one repository as $0,1,2$,
bos@88 232 while in another as $1,0,2$.
bos@88 233
bos@88 234 Mercurial uses revision numbers purely as a convenient shorthand. If
bos@88 235 you need to discuss a changeset with someone, or make a record of a
bos@88 236 changeset for some other reason (for example, in a bug report), use
bos@88 237 the hexadecimal identifier.
bos@88 238
bos@88 239 \subsection{Viewing specific revisions}
bos@88 240
bos@88 241 To narrow the output of \hgcmd{log} down to a single revision, use the
bos@91 242 \hgopt{log}{-r} (or \hgopt{log}{--rev}) option. You can use either a
bos@91 243 revision number or a long-form changeset identifier, and you can
bos@91 244 provide as many revisions as you want. \interaction{tour.log-r}
bos@88 245
bos@88 246 If you want to see the history of several revisions without having to
bos@88 247 list each one, you can use \emph{range notation}; this lets you
bos@88 248 express the idea ``I want all revisions between $a$ and $b$,
bos@88 249 inclusive''.
bos@88 250 \interaction{tour.log.range}
bos@88 251 Mercurial also honours the order in which you specify revisions, so
bos@88 252 \hgcmdargs{log}{-r 2:4} prints $2,3,4$ while \hgcmdargs{log}{-r 4:2}
bos@88 253 prints $4,3,2$.
bos@88 254
bos@91 255 \subsection{More detailed information}
bos@91 256
bos@91 257 While the summary information printed by \hgcmd{log} is useful if you
bos@91 258 already know what you're looking for, you may need to see a complete
bos@91 259 description of the change, or a list of the files changed, if you're
bos@91 260 trying to decide whether a changeset is the one you're looking for.
bos@91 261 The \hgcmd{log} command's \hggopt{-v} (or \hggopt{--verbose})
bos@91 262 option gives you this extra detail.
bos@91 263 \interaction{tour.log-v}
bos@91 264
bos@91 265 If you want to see both the description and content of a change, add
bos@91 266 the \hgopt{log}{-p} (or \hgopt{log}{--patch}) option. This displays
bos@91 267 the content of a change as a \emph{unified diff} (if you've never seen
bos@91 268 a unified diff before, see section~\ref{sec:mq:patch} for an overview).
bos@91 269 \interaction{tour.log-vp}
bos@91 270
bos@91 271 \section{All about command options}
bos@91 272
bos@91 273 Let's take a brief break from exploring Mercurial commands to discuss
bos@91 274 a pattern in the way that they work; you may find this useful to keep
steve@158 275 in mind as we continue our tour.
bos@91 276
bos@91 277 Mercurial has a consistent and straightforward approach to dealing
bos@91 278 with the options that you can pass to commands. It follows the
bos@91 279 conventions for options that are common to modern Linux and Unix
bos@91 280 systems.
bos@91 281 \begin{itemize}
bos@91 282 \item Every option has a long name. For example, as we've already
bos@91 283 seen, the \hgcmd{log} command accepts a \hgopt{log}{--rev} option.
bos@91 284 \item Most options have short names, too. Instead of
bos@91 285 \hgopt{log}{--rev}, we can use \hgopt{log}{-r}. (The reason that
bos@91 286 some options don't have short names is that the options in question
bos@91 287 are rarely used.)
bos@91 288 \item Long options start with two dashes (e.g.~\hgopt{log}{--rev}),
bos@91 289 while short options start with one (e.g.~\hgopt{log}{-r}).
bos@91 290 \item Option naming and usage is consistent across commands. For
bos@91 291 example, every command that lets you specify a changeset~ID or
bos@91 292 revision number accepts both \hgopt{log}{-r} and \hgopt{log}{--rev}
bos@91 293 arguments.
bos@91 294 \end{itemize}
bos@91 295 In the examples throughout this book, I use short options instead of
bos@91 296 long. This just reflects my own preference, so don't read anything
bos@91 297 significant into it.
bos@91 298
bos@91 299 Most commands that print output of some kind will print more output
bos@91 300 when passed a \hggopt{-v} (or \hggopt{--verbose}) option, and less
bos@91 301 when passed \hggopt{-q} (or \hggopt{--quiet}).
bos@91 302
bos@91 303 \section{Making and reviewing changes}
bos@91 304
bos@91 305 Now that we have a grasp of viewing history in Mercurial, let's take a
bos@91 306 look at making some changes and examining them.
bos@91 307
bos@91 308 The first thing we'll do is isolate our experiment in a repository of
bos@91 309 its own. We use the \hgcmd{clone} command, but we don't need to
bos@91 310 clone a copy of the remote repository. Since we already have a copy
bos@91 311 of it locally, we can just clone that instead. This is much faster
bos@91 312 than cloning over the network, and cloning a local repository uses
bos@91 313 less disk space in most cases, too.
bos@91 314 \interaction{tour.reclone}
bos@91 315 As an aside, it's often good practice to keep a ``pristine'' copy of a
bos@91 316 remote repository around, which you can then make temporary clones of
bos@91 317 to create sandboxes for each task you want to work on. This lets you
bos@91 318 work on multiple tasks in parallel, each isolated from the others
bos@91 319 until it's complete and you're ready to integrate it back. Because
bos@91 320 local clones are so cheap, there's almost no overhead to cloning and
bos@91 321 destroying repositories whenever you want.
bos@91 322
bos@91 323 In our \dirname{my-hello} repository, we have a file
bos@91 324 \filename{hello.c} that contains the classic ``hello, world'' program.
bos@91 325 Let's use the ancient and venerable \command{sed} command to edit this
bos@91 326 file so that it prints a second line of output. (I'm only using
bos@91 327 \command{sed} to do this because it's easy to write a scripted example
bos@91 328 this way. Since you're not under the same constraint, you probably
bos@91 329 won't want to use \command{sed}; simply use your preferred text editor to
bos@91 330 do the same thing.)
bos@91 331 \interaction{tour.sed}
bos@91 332
bos@91 333 Mercurial's \hgcmd{status} command will tell us what Mercurial knows
bos@91 334 about the files in the repository.
bos@91 335 \interaction{tour.status}
bos@91 336 The \hgcmd{status} command prints no output for some files, but a line
bos@91 337 starting with ``\texttt{M}'' for \filename{hello.c}. Unless you tell
bos@91 338 it to, \hgcmd{status} will not print any output for files that have
bos@91 339 not been modified.
bos@91 340
bos@91 341 The ``\texttt{M}'' indicates that Mercurial has noticed that we
bos@97 342 modified \filename{hello.c}. We didn't need to \emph{inform}
bos@97 343 Mercurial that we were going to modify the file before we started, or
bos@97 344 that we had modified the file after we were done; it was able to
bos@97 345 figure this out itself.
bos@91 346
bos@91 347 It's a little bit helpful to know that we've modified
bos@91 348 \filename{hello.c}, but we might prefer to know exactly \emph{what}
bos@91 349 changes we've made to it. To do this, we use the \hgcmd{diff}
bos@91 350 command.
bos@91 351 \interaction{tour.diff}
bos@91 352
bos@91 353 \section{Recording changes in a new changeset}
bos@91 354
bos@91 355 We can modify files, build and test our changes, and use
bos@91 356 \hgcmd{status} and \hgcmd{diff} to review our changes, until we're
bos@91 357 satisfied with what we've done and arrive at a natural stopping point
bos@91 358 where we want to record our work in a new changeset.
bos@91 359
bos@91 360 The \hgcmd{commit} command lets us create a new changeset; we'll
bos@91 361 usually refer to this as ``making a commit'' or ``committing''.
bos@91 362
bos@102 363 \subsection{Setting up a username}
bos@102 364
bos@174 365 When you try to run \hgcmd{commit} for the first time, it is not
bos@174 366 guaranteed to succeed. Mercurial records your name and address with
bos@174 367 each change that you commit, so that you and others will later be able
bos@174 368 to tell who made each change. Mercurial tries to automatically figure
bos@174 369 out a sensible username to commit the change with. It will attempt
bos@174 370 each of the following methods, in order:
bos@174 371 \begin{enumerate}
bos@174 372 \item If you specify a \hgopt{commit}{-u} option to the \hgcmd{commit}
bos@174 373 command on the command line, followed by a username, this is always
bos@174 374 given the highest precedence.
bos@174 375 \item If you have set the \envar{HGUSER} environment variable, this is
bos@174 376 checked next.
bos@174 377 \item If you create a file in your home directory called
bos@174 378 \sfilename{.hgrc}, with a \rcitem{ui}{username} entry, that will be
bos@174 379 used next. To see what the contents of this file should look like,
bos@174 380 refer to section~\ref{sec:tour-basic:username} below.
bos@174 381 \item If you have set the \envar{EMAIL} environment variable, this
bos@174 382 will be used next.
bos@174 383 \item Mercurial will query your system to find out your local user
bos@174 384 name and host name, and construct a username from these components.
bos@174 385 Since this often results in a username that is not very useful, it
bos@174 386 will print a warning if it has to do this.
bos@174 387 \end{enumerate}
bos@174 388 If all of these mechanisms fail, Mercurial will fail, printing an
bos@174 389 error message. In this case, it will not let you commit until you set
bos@174 390 up a username.
bos@174 391
bos@174 392 You should think of the \envar{HGUSER} environment variable and the
bos@174 393 \hgopt{commit}{-u} option to the \hgcmd{commit} command as ways to
bos@174 394 \emph{override} Mercurial's default selection of username. For normal
bos@174 395 use, the simplest and most robust way to set a username for yourself
bos@174 396 is by creating a \sfilename{.hgrc} file; see below for details.
bos@102 397
bos@102 398 \subsubsection{Creating a Mercurial configuration file}
bos@174 399 \label{sec:tour-basic:username}
bos@102 400
bos@102 401 To set a user name, use your favourite editor to create a file called
bos@102 402 \sfilename{.hgrc} in your home directory. Mercurial will use this
bos@102 403 file to look up your personalised configuration settings. The initial
bos@102 404 contents of your \sfilename{.hgrc} should look like this.
bos@102 405 \begin{codesample2}
bos@102 406 # This is a Mercurial configuration file.
bos@102 407 [ui]
bos@102 408 username = Firstname Lastname <email.address@domain.net>
bos@102 409 \end{codesample2}
bos@102 410 The ``\texttt{[ui]}'' line begins a \emph{section} of the config file,
bos@102 411 so you can read the ``\texttt{username = ...}'' line as meaning ``set
bos@102 412 the value of the \texttt{username} item in the \texttt{ui} section''.
bos@102 413 A section continues until a new section begins, or the end of the
bos@102 414 file. Mercurial ignores empty lines and treats any text from
bos@102 415 ``\texttt{\#}'' to the end of a line as a comment.
bos@102 416
bos@102 417 \subsubsection{Choosing a user name}
bos@102 418
bos@102 419 You can use any text you like as the value of the \texttt{username}
bos@102 420 config item, since this information is for reading by other people,
bos@102 421 but for interpreting by Mercurial. The convention that most people
bos@102 422 follow is to use their name and email address, as in the example
bos@102 423 above.
bos@102 424
bos@102 425 \begin{note}
bos@102 426 Mercurial's built-in web server obfuscates email addresses, to make
bos@102 427 it more difficult for the email harvesting tools that spammers use.
bos@102 428 This reduces the likelihood that you'll start receiving more junk
bos@102 429 email if you publish a Mercurial repository on the web.
bos@102 430 \end{note}
bos@102 431
bos@91 432 \subsection{Writing a commit message}
bos@91 433
bos@91 434 When we commit a change, Mercurial drops us into a text editor, to
bos@91 435 enter a message that will describe the modifications we've made in
bos@91 436 this changeset. This is called the \emph{commit message}. It will be
bos@91 437 a record for readers of what we did and why, and it will be printed by
bos@91 438 \hgcmd{log} after we've finished committing.
bos@91 439 \interaction{tour.commit}
bos@91 440
bos@91 441 The editor that the \hgcmd{commit} command drops us into will contain
bos@91 442 an empty line, followed by a number of lines starting with
bos@91 443 ``\texttt{HG:}''.
bos@91 444 \begin{codesample2}
bos@91 445 \emph{empty line}
bos@91 446 HG: changed hello.c
bos@91 447 \end{codesample2}
bos@91 448 Mercurial ignores the lines that start with ``\texttt{HG:}''; it uses
bos@91 449 them only to tell us which files it's recording changes to. Modifying
bos@91 450 or deleting these lines has no effect.
bos@91 451
bos@91 452 \subsection{Writing a good commit message}
bos@91 453
bos@91 454 Since \hgcmd{log} only prints the first line of a commit message by
bos@91 455 default, it's best to write a commit message whose first line stands
bos@91 456 alone. Here's a real example of a commit message that \emph{doesn't}
bos@91 457 follow this guideline, and hence has a summary that is not readable.
bos@91 458 \begin{codesample2}
bos@91 459 changeset: 73:584af0e231be
bos@91 460 user: Censored Person <censored.person@example.org>
bos@91 461 date: Tue Sep 26 21:37:07 2006 -0700
bos@91 462 summary: include buildmeister/commondefs. Add an exports and install
bos@91 463 \end{codesample2}
bos@91 464
bos@91 465 As far as the remainder of the contents of the commit message are
bos@91 466 concerned, there are no hard-and-fast rules. Mercurial itself doesn't
bos@91 467 interpret or care about the contents of the commit message, though
bos@91 468 your project may have policies that dictate a certain kind of
bos@91 469 formatting.
bos@91 470
bos@91 471 My personal preference is for short, but informative, commit messages
bos@91 472 that tell me something that I can't figure out with a quick glance at
bos@91 473 the output of \hgcmdargs{log}{--patch}.
bos@91 474
bos@91 475 \subsection{Aborting a commit}
bos@91 476
bos@91 477 If you decide that you don't want to commit while in the middle of
bos@91 478 editing a commit message, simply exit from your editor without saving
bos@91 479 the file that it's editing. This will cause nothing to happen to
bos@91 480 either the repository or the working directory.
bos@91 481
bos@91 482 If we run the \hgcmd{commit} command without any arguments, it records
bos@91 483 all of the changes we've made, as reported by \hgcmd{status} and
bos@91 484 \hgcmd{diff}.
bos@91 485
bos@102 486 \subsection{Admiring our new handiwork}
bos@91 487
bos@91 488 Once we've finished the commit, we can use the \hgcmd{tip} command to
bos@91 489 display the changeset we just created. This command produces output
bos@91 490 that is identical to \hgcmd{log}, but it only displays the newest
bos@91 491 revision in the repository.
bos@91 492 \interaction{tour.tip}
bos@91 493 We refer to the newest revision in the repository as the tip revision,
bos@91 494 or simply the tip.
bos@91 495
bos@91 496 \section{Sharing changes}
bos@91 497
bos@91 498 We mentioned earlier that repositories in Mercurial are
bos@91 499 self-contained. This means that the changeset we just created exists
bos@91 500 only in our \dirname{my-hello} repository. Let's look at a few ways
bos@91 501 that we can propagate this change into other repositories.
bos@91 502
bos@91 503 \subsection{Pulling changes from another repository}
bos@91 504 \label{sec:tour:pull}
bos@91 505
bos@91 506 To get started, let's clone our original \dirname{hello} repository,
bos@91 507 which does not contain the change we just committed. We'll call our
bos@91 508 temporary repository \dirname{hello-pull}.
bos@91 509 \interaction{tour.clone-pull}
bos@91 510
bos@91 511 We'll use the \hgcmd{pull} command to bring changes from
bos@91 512 \dirname{my-hello} into \dirname{hello-pull}. However, blindly
bos@91 513 pulling unknown changes into a repository is a somewhat scary
bos@91 514 prospect. Mercurial provides the \hgcmd{incoming} command to tell us
bos@91 515 what changes the \hgcmd{pull} command \emph{would} pull into the
bos@91 516 repository, without actually pulling the changes in.
bos@91 517 \interaction{tour.incoming}
bos@91 518 (Of course, someone could cause more changesets to appear in the
bos@91 519 repository that we ran \hgcmd{incoming} in, before we get a chance to
bos@91 520 \hgcmd{pull} the changes, so that we could end up pulling changes that we
bos@91 521 didn't expect.)
bos@91 522
bos@91 523 Bringing changes into a repository is a simple matter of running the
bos@91 524 \hgcmd{pull} command, and telling it which repository to pull from.
bos@91 525 \interaction{tour.pull}
bos@91 526 As you can see from the before-and-after output of \hgcmd{tip}, we
bos@91 527 have successfully pulled changes into our repository. There remains
bos@92 528 one step before we can see these changes in the working directory.
bos@92 529
bos@92 530 \subsection{Updating the working directory}
bos@92 531
bos@92 532 We have so far glossed over the relationship between a repository and
bos@91 533 its working directory. The \hgcmd{pull} command that we ran in
bos@91 534 section~\ref{sec:tour:pull} brought changes into the repository, but
bos@91 535 if we check, there's no sign of those changes in the working
bos@91 536 directory. This is because \hgcmd{pull} does not (by default) touch
bos@91 537 the working directory. Instead, we use the \hgcmd{update} command to
bos@91 538 do this.
bos@91 539 \interaction{tour.update}
bos@91 540
bos@91 541 It might seem a bit strange that \hgcmd{pull} doesn't update the
bos@91 542 working directory automatically. There's actually a good reason for
bos@91 543 this: you can use \hgcmd{update} to update the working directory to
bos@91 544 the state it was in at \emph{any revision} in the history of the
bos@91 545 repository. If you had the working directory updated to an old
bos@91 546 revision---to hunt down the origin of a bug, say---and ran a
bos@91 547 \hgcmd{pull} which automatically updated the working directory to a
bos@91 548 new revision, you might not be terribly happy.
bos@91 549
bos@91 550 However, since pull-then-update is such a common thing to do,
bos@91 551 Mercurial lets you combine the two by passing the \hgopt{pull}{-u}
bos@91 552 option to \hgcmd{pull}.
bos@91 553 \begin{codesample2}
bos@91 554 hg pull -u
bos@91 555 \end{codesample2}
bos@92 556 If you look back at the output of \hgcmd{pull} in
bos@92 557 section~\ref{sec:tour:pull} when we ran it without \hgopt{pull}{-u},
bos@92 558 you can see that it printed a helpful reminder that we'd have to take
bos@92 559 an explicit step to update the working directory:
bos@92 560 \begin{codesample2}
bos@92 561 (run 'hg update' to get a working copy)
bos@92 562 \end{codesample2}
bos@91 563
bos@91 564 To find out what revision the working directory is at, use the
bos@91 565 \hgcmd{parents} command.
bos@91 566 \interaction{tour.parents}
bos@101 567 If you look back at figure~\ref{fig:tour-basic:history}, you'll see
bos@101 568 arrows connecting each changeset. The node that the arrow leads
bos@101 569 \emph{from} in each case is a parent, and the node that the arrow
bos@101 570 leads \emph{to} is its child. The working directory has a parent in
bos@101 571 just the same way; this is the changeset that the working directory
bos@101 572 currently contains.
bos@101 573
bos@91 574 To update the working directory to a particular revision, give a
bos@91 575 revision number or changeset~ID to the \hgcmd{update} command.
bos@91 576 \interaction{tour.older}
bos@91 577 If you omit an explicit revision, \hgcmd{update} will update to the
bos@94 578 tip revision, as shown by the second call to \hgcmd{update} in the
bos@94 579 example above.
bos@91 580
bos@92 581 \subsection{Pushing changes to another repository}
bos@92 582
bos@92 583 Mercurial lets us push changes to another repository, from the
bos@92 584 repository we're currently visiting. As with the example of
bos@92 585 \hgcmd{pull} above, we'll create a temporary repository to push our
bos@92 586 changes into.
bos@92 587 \interaction{tour.clone-push}
bos@92 588 The \hgcmd{outgoing} command tells us what changes would be pushed
bos@92 589 into another repository.
bos@92 590 \interaction{tour.outgoing}
bos@92 591 And the \hgcmd{push} command does the actual push.
bos@92 592 \interaction{tour.push}
bos@92 593 As with \hgcmd{pull}, the \hgcmd{push} command does not update the
bos@92 594 working directory in the repository that it's pushing changes into.
bos@92 595 (Unlike \hgcmd{pull}, \hgcmd{push} does not provide a \texttt{-u}
bos@92 596 option that updates the other repository's working directory.)
bos@92 597
bos@92 598 What happens if we try to pull or push changes and the receiving
bos@92 599 repository already has those changes? Nothing too exciting.
bos@92 600 \interaction{tour.push.nothing}
bos@92 601
bos@93 602 \subsection{Sharing changes over a network}
bos@93 603
bos@93 604 The commands we have covered in the previous few sections are not
bos@93 605 limited to working with local repositories. Each works in exactly the
bos@93 606 same fashion over a network connection; simply pass in a URL instead
bos@93 607 of a local path.
bos@93 608 \interaction{tour.outgoing.net}
bos@93 609 In this example, we can see what changes we could push to the remote
bos@93 610 repository, but the repository is understandably not set up to let
bos@93 611 anonymous users push to it.
bos@93 612 \interaction{tour.push.net}
bos@93 613
bos@84 614 %%% Local Variables:
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bos@84 616 %%% TeX-master: "00book"
bos@84 617 %%% End: