hgbook
view es/tour-basic.tex @ 362:90b67ac5862b
translated up to section 1.4.1
| author | Javier Rojas <jerojasro@devnull.li> |
|---|---|
| date | Sat Oct 25 15:01:39 2008 -0500 (2008-10-25) |
| parents | 15a6b61335aa |
| children | e8a5068c7605 |
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 ficheros que
122 ``pertenecen a'' ése proyecto, junto con un registro histórico de los
123 ficheros de ese proyecto.
125 No hay nada particularmente mágico acerca de un repositorio; es
126 simplemente un árbol de directorios en su sistema de ficheros 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 ficheros 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 ficheros.
142 \interaction{tour.ls}
143 Estos ficheros 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 ficheros 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 fichero o directorio en el repositorio.
168 Para introducir algo de terminología, el directorio \dirname{.hg} es
169 el repositorio ``real'', y todos los ficheros 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 ficheros.
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}]\hspace{-0.5em}\ndt{Fecha.} La fecha y hora en la
207 que el conjunto de cambios fue creado, y la zona horaria en la que
208 fue creado. (La fecha y hora son locales a dicha zona horaria;
209 ambos muestran la fecha y hora para la persona que creó el
210 changeset).
212 \item[\texttt{summary}]\hspace{-0.5em}\ndt{Sumario.}
213 La primera línea del texto que usó la persona que creó el conjunto
214 de cambios para describir el mismo.
215 \end{itemize}
216 El texto impreso por \hgcmd{log} es sólo un sumario; omite una gran
217 cantidad de detalles.
219 La figura~\ref{fig:tour-basic:history} es una representación
220 gráfica del historial del repositorio \dirname{hello}, para hacer más
221 fácil ver en qué dirección está ``fluyendo'' el historial. Volveremos
222 a esto varias veces en este capítulo y en los siguientes.
224 \begin{figure}[ht]
225 \centering
226 \grafix{tour-history}
227 \caption{Historial gráfico de el repositorio \dirname{hello}}
228 \label{fig:tour-basic:history}
229 \end{figure}
231 \subsection{Conjuntos de cambios, revisiones, y comunicándose con
232 otras personas}
234 %TODO sloppy => desordenado ? TODO hablar del inglés? o de español?
235 Ya que el inglés es un lenguaje notablemente desordenado, y el área de
236 ciencias de la computación tiene una notable historia de confusión de
237 % TODO insertar ? al revés. no sé cómo en un teclado de estos.
238 términos (porqué usar sólo un término cuando cuatro pueden servir?),
239 el control de revisiones tiene una variedad de frases y palabras que
240 tienen el mismo significado. Si usted habla acerca del historial de
241 Mercurial con alguien, encontrará que la expresión ``conjunto de
242 cambios'' es abreviada a menudo como ``cambio'' o (por escrito)
243 ``cset''\ndt{Abreviatura para la expresión ``changeset'' en inglés.},
244 y algunas veces un se hace referencia a un conjunto de cambios como
245 una ``revisión'' o ``rev''\ndt{De nuevo, como abreviación para el
246 término en inglés para ``revisión'' (``revision'').}.
248 Si bien no es relevante qué \emph{palabra} use usted para referirse al
249 concepto ``conjunto de cambios'', el \emph{identificador} que usted
250 use para referise a ``un \emph{conjunto de cambios} particular'' es
251 muy importante. Recuerde que el campo \texttt{changeset} en la salida
252 de \hgcmd{log} identifica un conjunto de cambios usando tanto un
253 número como una cadena hexadecimal.
255 \begin{itemize}
256 \item El número de revisión \emph{sólo es válido dentro del
257 repositorio}.
258 \item Por otro lado, la cadena hexadecimal es el
259 \emph{identificador permanente e inmutable} que siempre
260 identificará ése conjunto de cambios en \emph{todas} las
261 copias del repositorio.
262 \end{itemize}
263 La diferencia es importante. Si usted le envía a alguien un correo
264 electrónico hablando acerca de la ``revisión~33'', hay una
265 probabilidad alta de que la revisión~33 de esa persona \emph{no sea la
266 misma suya}. Esto sucede porque el número de revisión depende de el
267 orden en que llegan los cambios al repositorio, y no hay ninguna
268 garantía de que los mismos cambios llegarán en el mismo orden en
269 diferentes repositorios. Tres cambios dados $a,b,c$ pueden aparecer en
270 un repositorio como $0,1,2$, mientras que en otro aparecen como
271 $1,0,2$.
273 Mercurial usa los números de revisión simplemente como una abreviación
274 conveniente. Si usted necesita hablar con alguien acerca de un
275 conjunto de cambios, o llevar el registro de un conjunto de cambios
276 por alguna otra razón (por ejemplo, en un reporte de fallo), use el
277 identificador hexadecimal.
279 \subsection{Viewing specific revisions}
281 To narrow the output of \hgcmd{log} down to a single revision, use the
282 \hgopt{log}{-r} (or \hgopt{log}{--rev}) option. You can use either a
283 revision number or a long-form changeset identifier, and you can
284 provide as many revisions as you want. \interaction{tour.log-r}
286 If you want to see the history of several revisions without having to
287 list each one, you can use \emph{range notation}; this lets you
288 express the idea ``I want all revisions between $a$ and $b$,
289 inclusive''.
290 \interaction{tour.log.range}
291 Mercurial also honours the order in which you specify revisions, so
292 \hgcmdargs{log}{-r 2:4} prints $2,3,4$ while \hgcmdargs{log}{-r 4:2}
293 prints $4,3,2$.
295 \subsection{More detailed information}
297 While the summary information printed by \hgcmd{log} is useful if you
298 already know what you're looking for, you may need to see a complete
299 description of the change, or a list of the files changed, if you're
300 trying to decide whether a changeset is the one you're looking for.
301 The \hgcmd{log} command's \hggopt{-v} (or \hggopt{--verbose})
302 option gives you this extra detail.
303 \interaction{tour.log-v}
305 If you want to see both the description and content of a change, add
306 the \hgopt{log}{-p} (or \hgopt{log}{--patch}) option. This displays
307 the content of a change as a \emph{unified diff} (if you've never seen
308 a unified diff before, see section~\ref{sec:mq:patch} for an overview).
309 \interaction{tour.log-vp}
311 \section{All about command options}
313 Let's take a brief break from exploring Mercurial commands to discuss
314 a pattern in the way that they work; you may find this useful to keep
315 in mind as we continue our tour.
317 Mercurial has a consistent and straightforward approach to dealing
318 with the options that you can pass to commands. It follows the
319 conventions for options that are common to modern Linux and Unix
320 systems.
321 \begin{itemize}
322 \item Every option has a long name. For example, as we've already
323 seen, the \hgcmd{log} command accepts a \hgopt{log}{--rev} option.
324 \item Most options have short names, too. Instead of
325 \hgopt{log}{--rev}, we can use \hgopt{log}{-r}. (The reason that
326 some options don't have short names is that the options in question
327 are rarely used.)
328 \item Long options start with two dashes (e.g.~\hgopt{log}{--rev}),
329 while short options start with one (e.g.~\hgopt{log}{-r}).
330 \item Option naming and usage is consistent across commands. For
331 example, every command that lets you specify a changeset~ID or
332 revision number accepts both \hgopt{log}{-r} and \hgopt{log}{--rev}
333 arguments.
334 \end{itemize}
335 In the examples throughout this book, I use short options instead of
336 long. This just reflects my own preference, so don't read anything
337 significant into it.
339 Most commands that print output of some kind will print more output
340 when passed a \hggopt{-v} (or \hggopt{--verbose}) option, and less
341 when passed \hggopt{-q} (or \hggopt{--quiet}).
343 \section{Making and reviewing changes}
345 Now that we have a grasp of viewing history in Mercurial, let's take a
346 look at making some changes and examining them.
348 The first thing we'll do is isolate our experiment in a repository of
349 its own. We use the \hgcmd{clone} command, but we don't need to
350 clone a copy of the remote repository. Since we already have a copy
351 of it locally, we can just clone that instead. This is much faster
352 than cloning over the network, and cloning a local repository uses
353 less disk space in most cases, too.
354 \interaction{tour.reclone}
355 As an aside, it's often good practice to keep a ``pristine'' copy of a
356 remote repository around, which you can then make temporary clones of
357 to create sandboxes for each task you want to work on. This lets you
358 work on multiple tasks in parallel, each isolated from the others
359 until it's complete and you're ready to integrate it back. Because
360 local clones are so cheap, there's almost no overhead to cloning and
361 destroying repositories whenever you want.
363 In our \dirname{my-hello} repository, we have a file
364 \filename{hello.c} that contains the classic ``hello, world'' program.
365 Let's use the ancient and venerable \command{sed} command to edit this
366 file so that it prints a second line of output. (I'm only using
367 \command{sed} to do this because it's easy to write a scripted example
368 this way. Since you're not under the same constraint, you probably
369 won't want to use \command{sed}; simply use your preferred text editor to
370 do the same thing.)
371 \interaction{tour.sed}
373 Mercurial's \hgcmd{status} command will tell us what Mercurial knows
374 about the files in the repository.
375 \interaction{tour.status}
376 The \hgcmd{status} command prints no output for some files, but a line
377 starting with ``\texttt{M}'' for \filename{hello.c}. Unless you tell
378 it to, \hgcmd{status} will not print any output for files that have
379 not been modified.
381 The ``\texttt{M}'' indicates that Mercurial has noticed that we
382 modified \filename{hello.c}. We didn't need to \emph{inform}
383 Mercurial that we were going to modify the file before we started, or
384 that we had modified the file after we were done; it was able to
385 figure this out itself.
387 It's a little bit helpful to know that we've modified
388 \filename{hello.c}, but we might prefer to know exactly \emph{what}
389 changes we've made to it. To do this, we use the \hgcmd{diff}
390 command.
391 \interaction{tour.diff}
393 \section{Recording changes in a new changeset}
395 We can modify files, build and test our changes, and use
396 \hgcmd{status} and \hgcmd{diff} to review our changes, until we're
397 satisfied with what we've done and arrive at a natural stopping point
398 where we want to record our work in a new changeset.
400 The \hgcmd{commit} command lets us create a new changeset; we'll
401 usually refer to this as ``making a commit'' or ``committing''.
403 \subsection{Setting up a username}
405 When you try to run \hgcmd{commit} for the first time, it is not
406 guaranteed to succeed. Mercurial records your name and address with
407 each change that you commit, so that you and others will later be able
408 to tell who made each change. Mercurial tries to automatically figure
409 out a sensible username to commit the change with. It will attempt
410 each of the following methods, in order:
411 \begin{enumerate}
412 \item If you specify a \hgopt{commit}{-u} option to the \hgcmd{commit}
413 command on the command line, followed by a username, this is always
414 given the highest precedence.
415 \item If you have set the \envar{HGUSER} environment variable, this is
416 checked next.
417 \item If you create a file in your home directory called
418 \sfilename{.hgrc}, with a \rcitem{ui}{username} entry, that will be
419 used next. To see what the contents of this file should look like,
420 refer to section~\ref{sec:tour-basic:username} below.
421 \item If you have set the \envar{EMAIL} environment variable, this
422 will be used next.
423 \item Mercurial will query your system to find out your local user
424 name and host name, and construct a username from these components.
425 Since this often results in a username that is not very useful, it
426 will print a warning if it has to do this.
427 \end{enumerate}
428 If all of these mechanisms fail, Mercurial will fail, printing an
429 error message. In this case, it will not let you commit until you set
430 up a username.
432 You should think of the \envar{HGUSER} environment variable and the
433 \hgopt{commit}{-u} option to the \hgcmd{commit} command as ways to
434 \emph{override} Mercurial's default selection of username. For normal
435 use, the simplest and most robust way to set a username for yourself
436 is by creating a \sfilename{.hgrc} file; see below for details.
438 \subsubsection{Creating a Mercurial configuration file}
439 \label{sec:tour-basic:username}
441 To set a user name, use your favourite editor to create a file called
442 \sfilename{.hgrc} in your home directory. Mercurial will use this
443 file to look up your personalised configuration settings. The initial
444 contents of your \sfilename{.hgrc} should look like this.
445 \begin{codesample2}
446 # This is a Mercurial configuration file.
447 [ui]
448 username = Firstname Lastname <email.address@domain.net>
449 \end{codesample2}
450 The ``\texttt{[ui]}'' line begins a \emph{section} of the config file,
451 so you can read the ``\texttt{username = ...}'' line as meaning ``set
452 the value of the \texttt{username} item in the \texttt{ui} section''.
453 A section continues until a new section begins, or the end of the
454 file. Mercurial ignores empty lines and treats any text from
455 ``\texttt{\#}'' to the end of a line as a comment.
457 \subsubsection{Choosing a user name}
459 You can use any text you like as the value of the \texttt{username}
460 config item, since this information is for reading by other people,
461 but for interpreting by Mercurial. The convention that most people
462 follow is to use their name and email address, as in the example
463 above.
465 \begin{note}
466 Mercurial's built-in web server obfuscates email addresses, to make
467 it more difficult for the email harvesting tools that spammers use.
468 This reduces the likelihood that you'll start receiving more junk
469 email if you publish a Mercurial repository on the web.
470 \end{note}
472 \subsection{Writing a commit message}
474 When we commit a change, Mercurial drops us into a text editor, to
475 enter a message that will describe the modifications we've made in
476 this changeset. This is called the \emph{commit message}. It will be
477 a record for readers of what we did and why, and it will be printed by
478 \hgcmd{log} after we've finished committing.
479 \interaction{tour.commit}
481 The editor that the \hgcmd{commit} command drops us into will contain
482 an empty line, followed by a number of lines starting with
483 ``\texttt{HG:}''.
484 \begin{codesample2}
485 \emph{empty line}
486 HG: changed hello.c
487 \end{codesample2}
488 Mercurial ignores the lines that start with ``\texttt{HG:}''; it uses
489 them only to tell us which files it's recording changes to. Modifying
490 or deleting these lines has no effect.
492 \subsection{Writing a good commit message}
494 Since \hgcmd{log} only prints the first line of a commit message by
495 default, it's best to write a commit message whose first line stands
496 alone. Here's a real example of a commit message that \emph{doesn't}
497 follow this guideline, and hence has a summary that is not readable.
498 \begin{codesample2}
499 changeset: 73:584af0e231be
500 user: Censored Person <censored.person@example.org>
501 date: Tue Sep 26 21:37:07 2006 -0700
502 summary: include buildmeister/commondefs. Add an exports and install
503 \end{codesample2}
505 As far as the remainder of the contents of the commit message are
506 concerned, there are no hard-and-fast rules. Mercurial itself doesn't
507 interpret or care about the contents of the commit message, though
508 your project may have policies that dictate a certain kind of
509 formatting.
511 My personal preference is for short, but informative, commit messages
512 that tell me something that I can't figure out with a quick glance at
513 the output of \hgcmdargs{log}{--patch}.
515 \subsection{Aborting a commit}
517 If you decide that you don't want to commit while in the middle of
518 editing a commit message, simply exit from your editor without saving
519 the file that it's editing. This will cause nothing to happen to
520 either the repository or the working directory.
522 If we run the \hgcmd{commit} command without any arguments, it records
523 all of the changes we've made, as reported by \hgcmd{status} and
524 \hgcmd{diff}.
526 \subsection{Admiring our new handiwork}
528 Once we've finished the commit, we can use the \hgcmd{tip} command to
529 display the changeset we just created. This command produces output
530 that is identical to \hgcmd{log}, but it only displays the newest
531 revision in the repository.
532 \interaction{tour.tip}
533 We refer to the newest revision in the repository as the tip revision,
534 or simply the tip.
536 \section{Sharing changes}
538 We mentioned earlier that repositories in Mercurial are
539 self-contained. This means that the changeset we just created exists
540 only in our \dirname{my-hello} repository. Let's look at a few ways
541 that we can propagate this change into other repositories.
543 \subsection{Pulling changes from another repository}
544 \label{sec:tour:pull}
546 To get started, let's clone our original \dirname{hello} repository,
547 which does not contain the change we just committed. We'll call our
548 temporary repository \dirname{hello-pull}.
549 \interaction{tour.clone-pull}
551 We'll use the \hgcmd{pull} command to bring changes from
552 \dirname{my-hello} into \dirname{hello-pull}. However, blindly
553 pulling unknown changes into a repository is a somewhat scary
554 prospect. Mercurial provides the \hgcmd{incoming} command to tell us
555 what changes the \hgcmd{pull} command \emph{would} pull into the
556 repository, without actually pulling the changes in.
557 \interaction{tour.incoming}
558 (Of course, someone could cause more changesets to appear in the
559 repository that we ran \hgcmd{incoming} in, before we get a chance to
560 \hgcmd{pull} the changes, so that we could end up pulling changes that we
561 didn't expect.)
563 Bringing changes into a repository is a simple matter of running the
564 \hgcmd{pull} command, and telling it which repository to pull from.
565 \interaction{tour.pull}
566 As you can see from the before-and-after output of \hgcmd{tip}, we
567 have successfully pulled changes into our repository. There remains
568 one step before we can see these changes in the working directory.
570 \subsection{Updating the working directory}
572 We have so far glossed over the relationship between a repository and
573 its working directory. The \hgcmd{pull} command that we ran in
574 section~\ref{sec:tour:pull} brought changes into the repository, but
575 if we check, there's no sign of those changes in the working
576 directory. This is because \hgcmd{pull} does not (by default) touch
577 the working directory. Instead, we use the \hgcmd{update} command to
578 do this.
579 \interaction{tour.update}
581 It might seem a bit strange that \hgcmd{pull} doesn't update the
582 working directory automatically. There's actually a good reason for
583 this: you can use \hgcmd{update} to update the working directory to
584 the state it was in at \emph{any revision} in the history of the
585 repository. If you had the working directory updated to an old
586 revision---to hunt down the origin of a bug, say---and ran a
587 \hgcmd{pull} which automatically updated the working directory to a
588 new revision, you might not be terribly happy.
590 However, since pull-then-update is such a common thing to do,
591 Mercurial lets you combine the two by passing the \hgopt{pull}{-u}
592 option to \hgcmd{pull}.
593 \begin{codesample2}
594 hg pull -u
595 \end{codesample2}
596 If you look back at the output of \hgcmd{pull} in
597 section~\ref{sec:tour:pull} when we ran it without \hgopt{pull}{-u},
598 you can see that it printed a helpful reminder that we'd have to take
599 an explicit step to update the working directory:
600 \begin{codesample2}
601 (run 'hg update' to get a working copy)
602 \end{codesample2}
604 To find out what revision the working directory is at, use the
605 \hgcmd{parents} command.
606 \interaction{tour.parents}
607 If you look back at figure~\ref{fig:tour-basic:history}, you'll see
608 arrows connecting each changeset. The node that the arrow leads
609 \emph{from} in each case is a parent, and the node that the arrow
610 leads \emph{to} is its child. The working directory has a parent in
611 just the same way; this is the changeset that the working directory
612 currently contains.
614 To update the working directory to a particular revision, give a
615 revision number or changeset~ID to the \hgcmd{update} command.
616 \interaction{tour.older}
617 If you omit an explicit revision, \hgcmd{update} will update to the
618 tip revision, as shown by the second call to \hgcmd{update} in the
619 example above.
621 \subsection{Pushing changes to another repository}
623 Mercurial lets us push changes to another repository, from the
624 repository we're currently visiting. As with the example of
625 \hgcmd{pull} above, we'll create a temporary repository to push our
626 changes into.
627 \interaction{tour.clone-push}
628 The \hgcmd{outgoing} command tells us what changes would be pushed
629 into another repository.
630 \interaction{tour.outgoing}
631 And the \hgcmd{push} command does the actual push.
632 \interaction{tour.push}
633 As with \hgcmd{pull}, the \hgcmd{push} command does not update the
634 working directory in the repository that it's pushing changes into.
635 (Unlike \hgcmd{pull}, \hgcmd{push} does not provide a \texttt{-u}
636 option that updates the other repository's working directory.)
638 What happens if we try to pull or push changes and the receiving
639 repository already has those changes? Nothing too exciting.
640 \interaction{tour.push.nothing}
642 \subsection{Sharing changes over a network}
644 The commands we have covered in the previous few sections are not
645 limited to working with local repositories. Each works in exactly the
646 same fashion over a network connection; simply pass in a URL instead
647 of a local path.
648 \interaction{tour.outgoing.net}
649 In this example, we can see what changes we could push to the remote
650 repository, but the repository is understandably not set up to let
651 anonymous users push to it.
652 \interaction{tour.push.net}
654 %%% Local Variables:
655 %%% mode: latex
656 %%% TeX-master: "00book"
657 %%% End: