hgbook
view es/tour-basic.tex @ 360:d4a0d7488a08
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| author | Igor TAmara <igor@tamarapatino.org> |
|---|---|
| date | Sat Oct 25 17:29:33 2008 -0500 (2008-10-25) |
| parents | dae36f024e14 |
| children | 90b67ac5862b |
line source
1 \chapter{Una gira de Mercurial: lo básico}
2 \label{chap:tour-basic}
4 \section{Instalar Mercurial en su sistema}
5 \label{sec:tour:install}
6 Hay paquetes binarios precompilados de Mercurial disponibles para cada
7 sistema operativo popular. Esto hace fácil empezar a usar Mercurial
8 en su computador inmediatamente.
10 \subsection{Linux}
12 Dado que cada distribución de Linux tiene sus propias herramientas de
13 manejo de paquetes, políticas, y ritmos de desarrollo, es difícil dar
14 un conjunto exhaustivo de instrucciones sobre cómo instalar el paquete
15 de Mercurial. La versión de Mercurial que usted tenga a disposición
16 puede variar dependiendo de qué tan activa sea la persona que mantiene
17 el paquete para su distribución.
19 Para mantener las cosas simples, me enfocaré en instalar Mercurial
20 desde la línea de comandos en las distribuciones de Linux más
21 populares. La mayoría de estas distribuciones proveen administradores
22 de paquetes gráficos que le permitirán instalar Mercurial con un solo
23 clic; el nombre de paquete a buscar es \texttt{mercurial}.
25 \begin{itemize}
26 \item[Debian]
27 \begin{codesample4}
28 apt-get install mercurial
29 \end{codesample4}
31 \item[Fedora Core]
32 \begin{codesample4}
33 yum install mercurial
34 \end{codesample4}
36 \item[Gentoo]
37 \begin{codesample4}
38 emerge mercurial
39 \end{codesample4}
41 \item[OpenSUSE]
42 \begin{codesample4}
43 yum install mercurial
44 \end{codesample4}
46 \item[Ubuntu] El paquete de Mercurial de Ubuntu está basado en el de
47 Debian. Para instalarlo, ejecute el siguiente comando.
48 \begin{codesample4}
49 apt-get install mercurial
50 \end{codesample4}
51 El paquete de Mercurial para Ubuntu tiende a atrasarse con respecto
52 a la versión de Debian por un margen de tiempo considerable
53 (al momento de escribir esto, 7 meses), lo que en algunos casos
54 significará que usted puede encontrarse con problemas que ya habrán
55 sido resueltos en el paquete de Debian.
56 \end{itemize}
58 \subsection{Solaris}
60 SunFreeWare, en \url{http://www.sunfreeware.com}, es una buena fuente
61 para un gran número de paquetes compilados para Solaris para las
62 arquitecturas Intel y Sparc de 32 y 64 bits, incluyendo versiones
63 actuales de Mercurial.
65 \subsection{Mac OS X}
67 Lee Cantey publica un instalador de Mercurial para Mac OS~X en
68 \url{http://mercurial.berkwood.com}. Este paquete funciona en tanto
69 en Macs basados en Intel como basados en PowerPC. Antes de que pueda
70 usarlo, usted debe instalar una versión compatible de Universal
71 MacPython~\cite{web:macpython}. Esto es fácil de hacer; simplemente
72 siga las instrucciones de el sitio de Lee.
74 También es posible instalar Mercurial usando Fink o MacPorts, dos
75 administradores de paquetes gratuitos y populares para Mac OS X. Si
76 usted tiene Fink, use \command{sudo apt-get install mercurial-py25}.
77 Si usa MacPorts, \command{sudo port install mercurial}.
79 \subsection{Windows}
81 Lee Cantey publica un instalador de Mercurial para Windows en
82 \url{http://mercurial.berkwood.com}. Este paquete no tiene
83 % TODO traducción de it just works. Agreed?
84 dependencias externas; ``simplemente funciona''.
86 \begin{note}
87 La versión de Windows de Mercurial no convierte automáticamente
88 los fines de línea entre estilos Windows y Unix. Si usted desea
89 compartir trabajo con usuarios de Unix, deberá hacer un trabajo
90 adicional de configuración. XXX Terminar esto.
91 \end{note}
93 \section{Arrancando}
95 Para empezar, usaremos el comando \hgcmd{version} para revisar si
96 Mercurial está instalado adecuadamente. La información de la versión
97 que es impresa no es tan importante; lo que nos importa es si imprime
98 algo en absoluto.
100 \interaction{tour.version}
102 % TODO builtin-> integrado?
103 \subsection{Ayuda integrada}
105 Mercurial provee un sistema de ayuda integrada. Esto es invaluable
106 para ésas ocasiones en la que usted está atorado tratando de recordar
107 cómo ejecutar un comando. Si está completamente atorado, simplemente
108 ejecute \hgcmd{help}; esto imprimirá una breve lista de comandos,
109 junto con una descripción de qué hace cada uno. Si usted solicita
110 ayuda sobre un comando específico (como abajo), se imprime información
111 más detallada.
112 \interaction{tour.help}
113 Para un nivel más impresionante de detalle (que usted no va a
114 necesitar usualmente) ejecute \hgcmdargs{help}{\hggopt{-v}}. La opción
115 \hggopt{-v} es la abreviación para \hggopt{--verbose}, y le indica a
116 Mercurial que imprima más información de lo que haría usualmente.
118 \section{Trabajar con un repositorio}
120 En Mercurial, todo sucede dentro de un \emph{repositorio}. El
121 repositorio para un proyecto contiene todos los archivos que
122 ``pertenecen a'' ése proyecto, junto con un registro histórico de los
123 archivos de ese proyecto.
125 No hay nada particularmente mágico acerca de un repositorio; es
126 simplemente un árbol de directorios en su sistema de archivos que
127 Mercurial trata como especial. Usted puede renombrar o borrar un
128 repositorio en el momento que lo desee, usando bien sea la línea de
129 comandos o su explorador de ficheros.
131 \subsection{Hacer una copia local de un repositorio}
133 \emph{Copiar} un repositorio es sólo ligeramente especial. Aunque
134 usted podría usar un programa normal de copia de archivos para hacer
135 una copia del repositorio, es mejor usar el comando integrado que
136 Mercurial ofrece. Este comando se llama \hgcmd{clone}\ndt{Del término
137 ``clonar'' en inglés.}, porque crea una copia idéntica de un
138 repositorio existente.
139 \interaction{tour.clone}
140 Si nuestro clonado tiene éxito, deberíamos tener un directorio local
141 llamado \dirname{hello}. Este directorio contendrá algunos archivos.
142 \interaction{tour.ls}
143 Estos archivos tienen el mismo contenido e historial en nuestro
144 repositorio y en el repositorio que clonamos.
146 Cada repositorio Mercurial está completo, es autocontenido e
147 independiente. Contiene su propia copia de los archivos y la historia
148 de un proyecto. Un repositorio clonado recuerda la ubicación de la que
149 fue clonado, pero no se comunica con ese repositorio, ni con ningún
150 otro, a menos que usted le indique que lo haga.
152 Lo que esto significa por ahora es que somos libres de experimentar
153 con nuestro repositorio, con la tranquilidad de saber que es una
154 % TODO figure out what to say instead of sandbox
155 ``caja de arena'' privada que no afectará a nadie más.
157 \subsection{Qué hay en un repositorio?}
159 Cuando miramos en detalle dentro de un repositorio, podemos ver que
160 contiene un directorio llamado \dirname{.hg}. Aquí es donde Mercurial
161 mantiene todos los metadatos del repositorio.
162 \interaction{tour.ls-a}
164 Los contenidos del directorio \dirname{.hg} y sus subdirectorios son
165 exclusivos de Mercurial. Usted es libre de hacer lo que desee con
166 cualquier otro archivo o directorio en el repositorio.
168 Para introducir algo de terminología, el directorio \dirname{.hg} es
169 el repositorio ``real'', y todos los archivos y directorios que
170 coexisten con él están en el \emph{directorio de trabajo}. Una forma
171 sencilla de recordar esta distinción es que el \emph{repositorio}
172 % TODO unificar con Igor, si historia o historial
173 contiene el \emph{historial} de su proyecto, mientras que el
174 \emph{directorio de trabajo} contiene una \emph{instantánea} de su
175 proyecto en un punto particular del historial.
177 \section{Vistazo rápido al historial}
179 Una de las primeras cosas que se desea hacer con un repositorio nuevo,
180 poco conocido, es conocer su historial. el comando \hgcmd{log} nos
181 permite ver el mismo.
182 \interaction{tour.log}
183 Por defecto este programa imprime un párrafo breve por cada cambio al
184 proyecto que haya sido grabado. Dentro de la terminología de
185 Mercurial, cada uno de estos eventos es llamado \emph{conjuntos de
186 cambios}, porque pueden contener un registro de cambios a varios
187 archivos.
189 Los campos de la salida de \hgcmd{log} son los siguientes.
190 \begin{itemize}
191 \item[\texttt{changeset}]\hspace{-0.5em}\ndt{Conjunto de cambios.} Este campo
192 tiene un número, seguido por un
193 % TODO digo mejor seguido por un dos puntos ? string =>
194 % cadena?
195 \texttt{:}, seguido por una cadena hexadecimal. Ambos son
196 \emph{identificadores} para el conjunto de cambios. Hay dos
197 identificadores porque el número es más corto y más fácil de
198 recordar que la cadena hexadecimal.
200 \item[\texttt{user}]\hspace{-0.5em}\ndt{Usuario.} La identidad de la
201 persona que creó el conjunto de cambios. Este es un campo en el
202 que se puede almacenar cualquier valor, pero en la mayoría de los
203 casos contiene el nombre de una persona y su dirección de correo
204 electrónico.
206 \item[\texttt{date}] The date and time on which the changeset was
207 created, and the timezone in which it was created. (The date and
208 time are local to that timezone; they display what time and date it
209 was for the person who created the changeset.)
210 \item[\texttt{summary}] The first line of the text message that the
211 creator of the changeset entered to describe the changeset.
212 \end{itemize}
213 The default output printed by \hgcmd{log} is purely a summary; it is
214 missing a lot of detail.
216 Figure~\ref{fig:tour-basic:history} provides a graphical representation of
217 the history of the \dirname{hello} repository, to make it a little
218 easier to see which direction history is ``flowing'' in. We'll be
219 returning to this figure several times in this chapter and the chapter
220 that follows.
222 \begin{figure}[ht]
223 \centering
224 \grafix{tour-history}
225 \caption{Graphical history of the \dirname{hello} repository}
226 \label{fig:tour-basic:history}
227 \end{figure}
229 \subsection{Changesets, revisions, and talking to other
230 people}
232 As English is a notoriously sloppy language, and computer science has
233 a hallowed history of terminological confusion (why use one term when
234 four will do?), revision control has a variety of words and phrases
235 that mean the same thing. If you are talking about Mercurial history
236 with other people, you will find that the word ``changeset'' is often
237 compressed to ``change'' or (when written) ``cset'', and sometimes a
238 changeset is referred to as a ``revision'' or a ``rev''.
240 While it doesn't matter what \emph{word} you use to refer to the
241 concept of ``a~changeset'', the \emph{identifier} that you use to
242 refer to ``a~\emph{specific} changeset'' is of great importance.
243 Recall that the \texttt{changeset} field in the output from
244 \hgcmd{log} identifies a changeset using both a number and a
245 hexadecimal string.
246 \begin{itemize}
247 \item The revision number is \emph{only valid in that repository},
248 \item while the hex string is the \emph{permanent, unchanging
249 identifier} that will always identify that exact changeset in
250 \emph{every} copy of the repository.
251 \end{itemize}
252 This distinction is important. If you send someone an email talking
253 about ``revision~33'', there's a high likelihood that their
254 revision~33 will \emph{not be the same} as yours. The reason for this
255 is that a revision number depends on the order in which changes
256 arrived in a repository, and there is no guarantee that the same
257 changes will happen in the same order in different repositories.
258 Three changes $a,b,c$ can easily appear in one repository as $0,1,2$,
259 while in another as $1,0,2$.
261 Mercurial uses revision numbers purely as a convenient shorthand. If
262 you need to discuss a changeset with someone, or make a record of a
263 changeset for some other reason (for example, in a bug report), use
264 the hexadecimal identifier.
266 \subsection{Viewing specific revisions}
268 To narrow the output of \hgcmd{log} down to a single revision, use the
269 \hgopt{log}{-r} (or \hgopt{log}{--rev}) option. You can use either a
270 revision number or a long-form changeset identifier, and you can
271 provide as many revisions as you want. \interaction{tour.log-r}
273 If you want to see the history of several revisions without having to
274 list each one, you can use \emph{range notation}; this lets you
275 express the idea ``I want all revisions between $a$ and $b$,
276 inclusive''.
277 \interaction{tour.log.range}
278 Mercurial also honours the order in which you specify revisions, so
279 \hgcmdargs{log}{-r 2:4} prints $2,3,4$ while \hgcmdargs{log}{-r 4:2}
280 prints $4,3,2$.
282 \subsection{More detailed information}
284 While the summary information printed by \hgcmd{log} is useful if you
285 already know what you're looking for, you may need to see a complete
286 description of the change, or a list of the files changed, if you're
287 trying to decide whether a changeset is the one you're looking for.
288 The \hgcmd{log} command's \hggopt{-v} (or \hggopt{--verbose})
289 option gives you this extra detail.
290 \interaction{tour.log-v}
292 If you want to see both the description and content of a change, add
293 the \hgopt{log}{-p} (or \hgopt{log}{--patch}) option. This displays
294 the content of a change as a \emph{unified diff} (if you've never seen
295 a unified diff before, see section~\ref{sec:mq:patch} for an overview).
296 \interaction{tour.log-vp}
298 \section{All about command options}
300 Let's take a brief break from exploring Mercurial commands to discuss
301 a pattern in the way that they work; you may find this useful to keep
302 in mind as we continue our tour.
304 Mercurial has a consistent and straightforward approach to dealing
305 with the options that you can pass to commands. It follows the
306 conventions for options that are common to modern Linux and Unix
307 systems.
308 \begin{itemize}
309 \item Every option has a long name. For example, as we've already
310 seen, the \hgcmd{log} command accepts a \hgopt{log}{--rev} option.
311 \item Most options have short names, too. Instead of
312 \hgopt{log}{--rev}, we can use \hgopt{log}{-r}. (The reason that
313 some options don't have short names is that the options in question
314 are rarely used.)
315 \item Long options start with two dashes (e.g.~\hgopt{log}{--rev}),
316 while short options start with one (e.g.~\hgopt{log}{-r}).
317 \item Option naming and usage is consistent across commands. For
318 example, every command that lets you specify a changeset~ID or
319 revision number accepts both \hgopt{log}{-r} and \hgopt{log}{--rev}
320 arguments.
321 \end{itemize}
322 In the examples throughout this book, I use short options instead of
323 long. This just reflects my own preference, so don't read anything
324 significant into it.
326 Most commands that print output of some kind will print more output
327 when passed a \hggopt{-v} (or \hggopt{--verbose}) option, and less
328 when passed \hggopt{-q} (or \hggopt{--quiet}).
330 \section{Making and reviewing changes}
332 Now that we have a grasp of viewing history in Mercurial, let's take a
333 look at making some changes and examining them.
335 The first thing we'll do is isolate our experiment in a repository of
336 its own. We use the \hgcmd{clone} command, but we don't need to
337 clone a copy of the remote repository. Since we already have a copy
338 of it locally, we can just clone that instead. This is much faster
339 than cloning over the network, and cloning a local repository uses
340 less disk space in most cases, too.
341 \interaction{tour.reclone}
342 As an aside, it's often good practice to keep a ``pristine'' copy of a
343 remote repository around, which you can then make temporary clones of
344 to create sandboxes for each task you want to work on. This lets you
345 work on multiple tasks in parallel, each isolated from the others
346 until it's complete and you're ready to integrate it back. Because
347 local clones are so cheap, there's almost no overhead to cloning and
348 destroying repositories whenever you want.
350 In our \dirname{my-hello} repository, we have a file
351 \filename{hello.c} that contains the classic ``hello, world'' program.
352 Let's use the ancient and venerable \command{sed} command to edit this
353 file so that it prints a second line of output. (I'm only using
354 \command{sed} to do this because it's easy to write a scripted example
355 this way. Since you're not under the same constraint, you probably
356 won't want to use \command{sed}; simply use your preferred text editor to
357 do the same thing.)
358 \interaction{tour.sed}
360 Mercurial's \hgcmd{status} command will tell us what Mercurial knows
361 about the files in the repository.
362 \interaction{tour.status}
363 The \hgcmd{status} command prints no output for some files, but a line
364 starting with ``\texttt{M}'' for \filename{hello.c}. Unless you tell
365 it to, \hgcmd{status} will not print any output for files that have
366 not been modified.
368 The ``\texttt{M}'' indicates that Mercurial has noticed that we
369 modified \filename{hello.c}. We didn't need to \emph{inform}
370 Mercurial that we were going to modify the file before we started, or
371 that we had modified the file after we were done; it was able to
372 figure this out itself.
374 It's a little bit helpful to know that we've modified
375 \filename{hello.c}, but we might prefer to know exactly \emph{what}
376 changes we've made to it. To do this, we use the \hgcmd{diff}
377 command.
378 \interaction{tour.diff}
380 \section{Recording changes in a new changeset}
382 We can modify files, build and test our changes, and use
383 \hgcmd{status} and \hgcmd{diff} to review our changes, until we're
384 satisfied with what we've done and arrive at a natural stopping point
385 where we want to record our work in a new changeset.
387 The \hgcmd{commit} command lets us create a new changeset; we'll
388 usually refer to this as ``making a commit'' or ``committing''.
390 \subsection{Setting up a username}
392 When you try to run \hgcmd{commit} for the first time, it is not
393 guaranteed to succeed. Mercurial records your name and address with
394 each change that you commit, so that you and others will later be able
395 to tell who made each change. Mercurial tries to automatically figure
396 out a sensible username to commit the change with. It will attempt
397 each of the following methods, in order:
398 \begin{enumerate}
399 \item If you specify a \hgopt{commit}{-u} option to the \hgcmd{commit}
400 command on the command line, followed by a username, this is always
401 given the highest precedence.
402 \item If you have set the \envar{HGUSER} environment variable, this is
403 checked next.
404 \item If you create a file in your home directory called
405 \sfilename{.hgrc}, with a \rcitem{ui}{username} entry, that will be
406 used next. To see what the contents of this file should look like,
407 refer to section~\ref{sec:tour-basic:username} below.
408 \item If you have set the \envar{EMAIL} environment variable, this
409 will be used next.
410 \item Mercurial will query your system to find out your local user
411 name and host name, and construct a username from these components.
412 Since this often results in a username that is not very useful, it
413 will print a warning if it has to do this.
414 \end{enumerate}
415 If all of these mechanisms fail, Mercurial will fail, printing an
416 error message. In this case, it will not let you commit until you set
417 up a username.
419 You should think of the \envar{HGUSER} environment variable and the
420 \hgopt{commit}{-u} option to the \hgcmd{commit} command as ways to
421 \emph{override} Mercurial's default selection of username. For normal
422 use, the simplest and most robust way to set a username for yourself
423 is by creating a \sfilename{.hgrc} file; see below for details.
425 \subsubsection{Creating a Mercurial configuration file}
426 \label{sec:tour-basic:username}
428 To set a user name, use your favourite editor to create a file called
429 \sfilename{.hgrc} in your home directory. Mercurial will use this
430 file to look up your personalised configuration settings. The initial
431 contents of your \sfilename{.hgrc} should look like this.
432 \begin{codesample2}
433 # This is a Mercurial configuration file.
434 [ui]
435 username = Firstname Lastname <email.address@domain.net>
436 \end{codesample2}
437 The ``\texttt{[ui]}'' line begins a \emph{section} of the config file,
438 so you can read the ``\texttt{username = ...}'' line as meaning ``set
439 the value of the \texttt{username} item in the \texttt{ui} section''.
440 A section continues until a new section begins, or the end of the
441 file. Mercurial ignores empty lines and treats any text from
442 ``\texttt{\#}'' to the end of a line as a comment.
444 \subsubsection{Choosing a user name}
446 You can use any text you like as the value of the \texttt{username}
447 config item, since this information is for reading by other people,
448 but for interpreting by Mercurial. The convention that most people
449 follow is to use their name and email address, as in the example
450 above.
452 \begin{note}
453 Mercurial's built-in web server obfuscates email addresses, to make
454 it more difficult for the email harvesting tools that spammers use.
455 This reduces the likelihood that you'll start receiving more junk
456 email if you publish a Mercurial repository on the web.
457 \end{note}
459 \subsection{Writing a commit message}
461 When we commit a change, Mercurial drops us into a text editor, to
462 enter a message that will describe the modifications we've made in
463 this changeset. This is called the \emph{commit message}. It will be
464 a record for readers of what we did and why, and it will be printed by
465 \hgcmd{log} after we've finished committing.
466 \interaction{tour.commit}
468 The editor that the \hgcmd{commit} command drops us into will contain
469 an empty line, followed by a number of lines starting with
470 ``\texttt{HG:}''.
471 \begin{codesample2}
472 \emph{empty line}
473 HG: changed hello.c
474 \end{codesample2}
475 Mercurial ignores the lines that start with ``\texttt{HG:}''; it uses
476 them only to tell us which files it's recording changes to. Modifying
477 or deleting these lines has no effect.
479 \subsection{Writing a good commit message}
481 Since \hgcmd{log} only prints the first line of a commit message by
482 default, it's best to write a commit message whose first line stands
483 alone. Here's a real example of a commit message that \emph{doesn't}
484 follow this guideline, and hence has a summary that is not readable.
485 \begin{codesample2}
486 changeset: 73:584af0e231be
487 user: Censored Person <censored.person@example.org>
488 date: Tue Sep 26 21:37:07 2006 -0700
489 summary: include buildmeister/commondefs. Add an exports and install
490 \end{codesample2}
492 As far as the remainder of the contents of the commit message are
493 concerned, there are no hard-and-fast rules. Mercurial itself doesn't
494 interpret or care about the contents of the commit message, though
495 your project may have policies that dictate a certain kind of
496 formatting.
498 My personal preference is for short, but informative, commit messages
499 that tell me something that I can't figure out with a quick glance at
500 the output of \hgcmdargs{log}{--patch}.
502 \subsection{Aborting a commit}
504 If you decide that you don't want to commit while in the middle of
505 editing a commit message, simply exit from your editor without saving
506 the file that it's editing. This will cause nothing to happen to
507 either the repository or the working directory.
509 If we run the \hgcmd{commit} command without any arguments, it records
510 all of the changes we've made, as reported by \hgcmd{status} and
511 \hgcmd{diff}.
513 \subsection{Admiring our new handiwork}
515 Once we've finished the commit, we can use the \hgcmd{tip} command to
516 display the changeset we just created. This command produces output
517 that is identical to \hgcmd{log}, but it only displays the newest
518 revision in the repository.
519 \interaction{tour.tip}
520 We refer to the newest revision in the repository as the tip revision,
521 or simply the tip.
523 \section{Sharing changes}
525 We mentioned earlier that repositories in Mercurial are
526 self-contained. This means that the changeset we just created exists
527 only in our \dirname{my-hello} repository. Let's look at a few ways
528 that we can propagate this change into other repositories.
530 \subsection{Pulling changes from another repository}
531 \label{sec:tour:pull}
533 To get started, let's clone our original \dirname{hello} repository,
534 which does not contain the change we just committed. We'll call our
535 temporary repository \dirname{hello-pull}.
536 \interaction{tour.clone-pull}
538 We'll use the \hgcmd{pull} command to bring changes from
539 \dirname{my-hello} into \dirname{hello-pull}. However, blindly
540 pulling unknown changes into a repository is a somewhat scary
541 prospect. Mercurial provides the \hgcmd{incoming} command to tell us
542 what changes the \hgcmd{pull} command \emph{would} pull into the
543 repository, without actually pulling the changes in.
544 \interaction{tour.incoming}
545 (Of course, someone could cause more changesets to appear in the
546 repository that we ran \hgcmd{incoming} in, before we get a chance to
547 \hgcmd{pull} the changes, so that we could end up pulling changes that we
548 didn't expect.)
550 Bringing changes into a repository is a simple matter of running the
551 \hgcmd{pull} command, and telling it which repository to pull from.
552 \interaction{tour.pull}
553 As you can see from the before-and-after output of \hgcmd{tip}, we
554 have successfully pulled changes into our repository. There remains
555 one step before we can see these changes in the working directory.
557 \subsection{Updating the working directory}
559 We have so far glossed over the relationship between a repository and
560 its working directory. The \hgcmd{pull} command that we ran in
561 section~\ref{sec:tour:pull} brought changes into the repository, but
562 if we check, there's no sign of those changes in the working
563 directory. This is because \hgcmd{pull} does not (by default) touch
564 the working directory. Instead, we use the \hgcmd{update} command to
565 do this.
566 \interaction{tour.update}
568 It might seem a bit strange that \hgcmd{pull} doesn't update the
569 working directory automatically. There's actually a good reason for
570 this: you can use \hgcmd{update} to update the working directory to
571 the state it was in at \emph{any revision} in the history of the
572 repository. If you had the working directory updated to an old
573 revision---to hunt down the origin of a bug, say---and ran a
574 \hgcmd{pull} which automatically updated the working directory to a
575 new revision, you might not be terribly happy.
577 However, since pull-then-update is such a common thing to do,
578 Mercurial lets you combine the two by passing the \hgopt{pull}{-u}
579 option to \hgcmd{pull}.
580 \begin{codesample2}
581 hg pull -u
582 \end{codesample2}
583 If you look back at the output of \hgcmd{pull} in
584 section~\ref{sec:tour:pull} when we ran it without \hgopt{pull}{-u},
585 you can see that it printed a helpful reminder that we'd have to take
586 an explicit step to update the working directory:
587 \begin{codesample2}
588 (run 'hg update' to get a working copy)
589 \end{codesample2}
591 To find out what revision the working directory is at, use the
592 \hgcmd{parents} command.
593 \interaction{tour.parents}
594 If you look back at figure~\ref{fig:tour-basic:history}, you'll see
595 arrows connecting each changeset. The node that the arrow leads
596 \emph{from} in each case is a parent, and the node that the arrow
597 leads \emph{to} is its child. The working directory has a parent in
598 just the same way; this is the changeset that the working directory
599 currently contains.
601 To update the working directory to a particular revision, give a
602 revision number or changeset~ID to the \hgcmd{update} command.
603 \interaction{tour.older}
604 If you omit an explicit revision, \hgcmd{update} will update to the
605 tip revision, as shown by the second call to \hgcmd{update} in the
606 example above.
608 \subsection{Pushing changes to another repository}
610 Mercurial lets us push changes to another repository, from the
611 repository we're currently visiting. As with the example of
612 \hgcmd{pull} above, we'll create a temporary repository to push our
613 changes into.
614 \interaction{tour.clone-push}
615 The \hgcmd{outgoing} command tells us what changes would be pushed
616 into another repository.
617 \interaction{tour.outgoing}
618 And the \hgcmd{push} command does the actual push.
619 \interaction{tour.push}
620 As with \hgcmd{pull}, the \hgcmd{push} command does not update the
621 working directory in the repository that it's pushing changes into.
622 (Unlike \hgcmd{pull}, \hgcmd{push} does not provide a \texttt{-u}
623 option that updates the other repository's working directory.)
625 What happens if we try to pull or push changes and the receiving
626 repository already has those changes? Nothing too exciting.
627 \interaction{tour.push.nothing}
629 \subsection{Sharing changes over a network}
631 The commands we have covered in the previous few sections are not
632 limited to working with local repositories. Each works in exactly the
633 same fashion over a network connection; simply pass in a URL instead
634 of a local path.
635 \interaction{tour.outgoing.net}
636 In this example, we can see what changes we could push to the remote
637 repository, but the repository is understandably not set up to let
638 anonymous users push to it.
639 \interaction{tour.push.net}
641 %%% Local Variables:
642 %%% mode: latex
643 %%% TeX-master: "00book"
644 %%% End: