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author Javier Rojas <jerojasro@devnull.li>
date Thu Oct 23 03:13:35 2008 -0500 (2008-10-23)
parents 5e325122bea5
children 15a6b61335aa
rev   line source
jerojasro@343 1 \chapter{Una gira de Mercurial: lo básico}
jerojasro@343 2 \label{chap:tour-basic}
jerojasro@343 3
jerojasro@343 4 \section{Instalar Mercurial en su sistema}
jerojasro@343 5 \label{sec:tour:install}
jerojasro@343 6 Hay paquetes binarios precompilados de Mercurial disponibles para cada
jerojasro@343 7 sistema operativo popular. Esto hace fácil empezar a usar Mercurial
jerojasro@343 8 en su computador inmediatamente.
jerojasro@343 9
jerojasro@343 10 \subsection{Linux}
jerojasro@343 11
jerojasro@343 12 Dado que cada distribución de Linux tiene sus propias herramientas de
jerojasro@343 13 manejo de paquetes, políticas, y ritmos de desarrollo, es difícil dar
jerojasro@343 14 un conjunto exhaustivo de instrucciones sobre cómo instalar el paquete
jerojasro@343 15 de Mercurial. La versión de Mercurial que usted tenga a disposición
jerojasro@343 16 puede variar dependiendo de qué tan activa sea la persona que mantiene
jerojasro@343 17 el paquete para su distribución.
jerojasro@343 18
jerojasro@343 19 Para mantener las cosas simples, me enfocaré en instalar Mercurial
jerojasro@343 20 desde la línea de comandos en las distribuciones de Linux más
jerojasro@343 21 populares. La mayoría de estas distribuciones proveen administradores
jerojasro@343 22 de paquetes gráficos que le permitirán instalar Mercurial con un solo
jerojasro@343 23 clic; el nombre de paquete a buscar es \texttt{mercurial}.
jerojasro@343 24
jerojasro@343 25 \begin{itemize}
jerojasro@343 26 \item[Debian]
jerojasro@343 27 \begin{codesample4}
jerojasro@343 28 apt-get install mercurial
jerojasro@343 29 \end{codesample4}
jerojasro@343 30
jerojasro@343 31 \item[Fedora Core]
jerojasro@343 32 \begin{codesample4}
jerojasro@343 33 yum install mercurial
jerojasro@343 34 \end{codesample4}
jerojasro@343 35
jerojasro@343 36 \item[Gentoo]
jerojasro@343 37 \begin{codesample4}
jerojasro@343 38 emerge mercurial
jerojasro@343 39 \end{codesample4}
jerojasro@343 40
jerojasro@343 41 \item[OpenSUSE]
jerojasro@343 42 \begin{codesample4}
jerojasro@343 43 yum install mercurial
jerojasro@343 44 \end{codesample4}
jerojasro@343 45
jerojasro@343 46 \item[Ubuntu] El paquete de Mercurial de Ubuntu está basado en el de
jerojasro@343 47 Debian. Para instalarlo, ejecute el siguiente comando.
jerojasro@343 48 \begin{codesample4}
jerojasro@343 49 apt-get install mercurial
jerojasro@343 50 \end{codesample4}
jerojasro@343 51 El paquete de Mercurial para Ubuntu tiende a atrasarse con respecto
jerojasro@343 52 a la versión de Debian por un margen de tiempo considerable
jerojasro@343 53 (al momento de escribir esto, 7 meses), lo que en algunos casos
jerojasro@343 54 significará que usted puede encontrarse con problemas que ya habrán
jerojasro@343 55 sido resueltos en el paquete de Debian.
jerojasro@343 56 \end{itemize}
jerojasro@343 57
jerojasro@343 58 \subsection{Solaris}
jerojasro@343 59
jerojasro@343 60 SunFreeWare, en \url{http://www.sunfreeware.com}, es una buena fuente
jerojasro@343 61 para un gran número de paquetes compilados para Solaris para las
jerojasro@343 62 arquitecturas Intel y Sparc de 32 y 64 bits, incluyendo versiones
jerojasro@343 63 actuales de Mercurial.
jerojasro@343 64
jerojasro@343 65 \subsection{Mac OS X}
jerojasro@343 66
jerojasro@343 67 Lee Cantey publica un instalador de Mercurial para Mac OS~X en
jerojasro@343 68 \url{http://mercurial.berkwood.com}. Este paquete funciona en tanto
jerojasro@343 69 en Macs basados en Intel como basados en PowerPC. Antes de que pueda
jerojasro@343 70 usarlo, usted debe instalar una versión compatible de Universal
jerojasro@343 71 MacPython~\cite{web:macpython}. Esto es fácil de hacer; simplemente
jerojasro@343 72 siga las instrucciones de el sitio de Lee.
jerojasro@343 73
jerojasro@343 74 También es posible instalar Mercurial usando Fink o MacPorts, dos
jerojasro@343 75 administradores de paquetes gratuitos y populares para Mac OS X. Si
jerojasro@343 76 usted tiene Fink, use \command{sudo apt-get install mercurial-py25}.
jerojasro@343 77 Si usa MacPorts, \command{sudo port install mercurial}.
jerojasro@343 78
jerojasro@343 79 \subsection{Windows}
jerojasro@343 80
jerojasro@343 81 Lee Cantey publica un instalador de Mercurial para Windows en
jerojasro@343 82 \url{http://mercurial.berkwood.com}. Este paquete no tiene
jerojasro@343 83 % TODO traducción de it just works. Agreed?
jerojasro@343 84 dependencias externas; ``simplemente funciona''.
jerojasro@343 85
jerojasro@343 86 \begin{note}
jerojasro@343 87 La versión de Windows de Mercurial no convierte automáticamente
jerojasro@343 88 los fines de línea entre estilos Windows y Unix. Si usted desea
jerojasro@343 89 compartir trabajo con usuarios de Unix, deberá hacer un trabajo
jerojasro@343 90 adicional de configuración. XXX Terminar esto.
jerojasro@343 91 \end{note}
jerojasro@343 92
jerojasro@343 93 \section{Arrancando}
jerojasro@343 94
jerojasro@343 95 Para empezar, usaremos el comando \hgcmd{version} para revisar si
jerojasro@343 96 Mercurial está instalado adecuadamente. La información de la versión
jerojasro@343 97 que es impresa no es tan importante; lo que nos importa es si imprime
jerojasro@343 98 algo en absoluto.
jerojasro@343 99
jerojasro@343 100 \interaction{tour.version}
jerojasro@343 101
jerojasro@343 102 % TODO builtin-> integrado?
jerojasro@343 103 \subsection{Ayuda integrada}
jerojasro@343 104
jerojasro@343 105 Mercurial provee un sistema de ayuda integrada. Esto es invaluable
jerojasro@343 106 para ésas ocasiones en la que usted está atorado tratando de recordar
jerojasro@343 107 cómo ejecutar un comando. Si está completamente atorado, simplemente
jerojasro@343 108 ejecute \hgcmd{help}; esto imprimirá una breve lista de comandos,
jerojasro@343 109 junto con una descripción de qué hace cada uno. Si usted solicita
jerojasro@343 110 ayuda sobre un comando específico (como abajo), se imprime información
jerojasro@343 111 más detallada.
jerojasro@343 112 \interaction{tour.help}
jerojasro@343 113 Para un nivel más impresionante de detalle (que usted no va a
jerojasro@343 114 necesitar usualmente) ejecute \hgcmdargs{help}{\hggopt{-v}}. La opción
jerojasro@343 115 \hggopt{-v} es la abreviación para \hggopt{--verbose}, y le indica a
jerojasro@343 116 Mercurial que imprima más información de lo que haría usualmente.
jerojasro@343 117
jerojasro@352 118 \section{Trabajar con un repositorio}
jerojasro@352 119
jerojasro@352 120 En Mercurial, todo sucede dentro de un \emph{repositorio}. El
jerojasro@352 121 repositorio para un proyecto contiene todos los archivos que
jerojasro@352 122 ``pertenecen a'' ése proyecto, junto con un registro histórico de los
jerojasro@352 123 archivos de ese proyecto.
jerojasro@352 124
jerojasro@352 125 No hay nada particularmente mágico acerca de un repositorio; es
jerojasro@352 126 simplemente un árbol de directorios en su sistema de archivos que
jerojasro@352 127 Mercurial trata como especial. Usted puede renombrar o borrar un
jerojasro@352 128 repositorio en el momento que lo desee, usando bien sea la línea de
jerojasro@352 129 comandos o su explorador de ficheros.
jerojasro@352 130
jerojasro@352 131 \subsection{Hacer una copia local de un repositorio}
jerojasro@352 132
jerojasro@352 133 \emph{Copiar} un repositorio es sólo ligeramente especial. Aunque
jerojasro@352 134 usted podría usar un programa normal de copia de archivos para hacer
jerojasro@352 135 una copia del repositorio, es mejor usar el comando integrado que
jerojasro@352 136 Mercurial ofrece. Este comando se llama \hgcmd{clone}\ndt{Del término
jerojasro@352 137 ``clonar'' en inglés.}, porque crea una copia idéntica de un
jerojasro@352 138 repositorio existente.
jerojasro@343 139 \interaction{tour.clone}
jerojasro@352 140 Si nuestro clonado tiene éxito, deberíamos tener un directorio local
jerojasro@352 141 llamado \dirname{hello}. Este directorio contendrá algunos archivos.
jerojasro@343 142 \interaction{tour.ls}
jerojasro@352 143 Estos archivos tienen el mismo contenido e historial en nuestro
jerojasro@352 144 repositorio y en el repositorio que clonamos.
jerojasro@352 145
jerojasro@352 146 Cada repositorio Mercurial está completo, es autocontenido e
jerojasro@352 147 independiente. Contiene su propia copia de los archivos y la historia
jerojasro@352 148 de un proyecto. Un repositorio clonado recuerda la ubicación de la que
jerojasro@352 149 fue clonado, pero no se comunica con ese repositorio, ni con ningún
jerojasro@352 150 otro, a menos que usted le indique que lo haga.
jerojasro@352 151
jerojasro@352 152 Lo que esto significa por ahora es que somos libres de experimentar
jerojasro@355 153 con nuestro repositorio, con la tranquilidad de saber que es una
jerojasro@355 154 % TODO figure out what to say instead of sandbox
jerojasro@355 155 ``caja de arena'' privada que no afectará a nadie más.
jerojasro@355 156
jerojasro@355 157 \subsection{Qué hay en un repositorio?}
jerojasro@355 158
jerojasro@355 159 Cuando miramos en detalle dentro de un repositorio, podemos ver que
jerojasro@355 160 contiene un directorio llamado \dirname{.hg}. Aquí es donde Mercurial
jerojasro@355 161 mantiene todos los metadatos del repositorio.
jerojasro@343 162 \interaction{tour.ls-a}
jerojasro@343 163
jerojasro@355 164 Los contenidos del directorio \dirname{.hg} y sus subdirectorios son
jerojasro@355 165 exclusivos de Mercurial. Usted es libre de hacer lo que desee con
jerojasro@355 166 cualquier otro archivo o directorio en el repositorio.
jerojasro@343 167
jerojasro@357 168 Para introducir algo de terminología, el directorio \dirname{.hg} es
jerojasro@357 169 el repositorio ``real'', y todos los archivos y directorios que
jerojasro@357 170 coexisten con él están en el \emph{directorio de trabajo}. Una forma
jerojasro@357 171 sencilla de recordar esta distinción es que el \emph{repositorio}
jerojasro@357 172 % TODO unificar con Igor, si historia o historial
jerojasro@357 173 contiene el \emph{historial} de su proyecto, mientras que el
jerojasro@357 174 \emph{directorio de trabajo} contiene una \emph{instantánea} de su
jerojasro@357 175 proyecto en un punto particular del historial.
jerojasro@357 176
jerojasro@357 177 \section{Vistazo rápido al historial}
jerojasro@357 178
jerojasro@357 179 Una de las primeras cosas que se desea hacer con un repositorio nuevo,
jerojasro@357 180 poco conocido, es conocer su historial. el comando \hgcmd{log} nos
jerojasro@357 181 permite ver el mismo.
jerojasro@343 182 \interaction{tour.log}
jerojasro@343 183 By default, this command prints a brief paragraph of output for each
jerojasro@343 184 change to the project that was recorded. In Mercurial terminology, we
jerojasro@343 185 call each of these recorded events a \emph{changeset}, because it can
jerojasro@343 186 contain a record of changes to several files.
jerojasro@343 187
jerojasro@343 188 The fields in a record of output from \hgcmd{log} are as follows.
jerojasro@343 189 \begin{itemize}
jerojasro@343 190 \item[\texttt{changeset}] This field has the format of a number,
jerojasro@343 191 followed by a colon, followed by a hexadecimal string. These are
jerojasro@343 192 \emph{identifiers} for the changeset. There are two identifiers
jerojasro@343 193 because the number is shorter and easier to type than the hex
jerojasro@343 194 string.
jerojasro@343 195 \item[\texttt{user}] The identity of the person who created the
jerojasro@343 196 changeset. This is a free-form field, but it most often contains a
jerojasro@343 197 person's name and email address.
jerojasro@343 198 \item[\texttt{date}] The date and time on which the changeset was
jerojasro@343 199 created, and the timezone in which it was created. (The date and
jerojasro@343 200 time are local to that timezone; they display what time and date it
jerojasro@343 201 was for the person who created the changeset.)
jerojasro@343 202 \item[\texttt{summary}] The first line of the text message that the
jerojasro@343 203 creator of the changeset entered to describe the changeset.
jerojasro@343 204 \end{itemize}
jerojasro@343 205 The default output printed by \hgcmd{log} is purely a summary; it is
jerojasro@343 206 missing a lot of detail.
jerojasro@343 207
jerojasro@343 208 Figure~\ref{fig:tour-basic:history} provides a graphical representation of
jerojasro@343 209 the history of the \dirname{hello} repository, to make it a little
jerojasro@343 210 easier to see which direction history is ``flowing'' in. We'll be
jerojasro@343 211 returning to this figure several times in this chapter and the chapter
jerojasro@343 212 that follows.
jerojasro@343 213
jerojasro@343 214 \begin{figure}[ht]
jerojasro@343 215 \centering
jerojasro@343 216 \grafix{tour-history}
jerojasro@343 217 \caption{Graphical history of the \dirname{hello} repository}
jerojasro@343 218 \label{fig:tour-basic:history}
jerojasro@343 219 \end{figure}
jerojasro@343 220
jerojasro@343 221 \subsection{Changesets, revisions, and talking to other
jerojasro@343 222 people}
jerojasro@343 223
jerojasro@343 224 As English is a notoriously sloppy language, and computer science has
jerojasro@343 225 a hallowed history of terminological confusion (why use one term when
jerojasro@343 226 four will do?), revision control has a variety of words and phrases
jerojasro@343 227 that mean the same thing. If you are talking about Mercurial history
jerojasro@343 228 with other people, you will find that the word ``changeset'' is often
jerojasro@343 229 compressed to ``change'' or (when written) ``cset'', and sometimes a
jerojasro@343 230 changeset is referred to as a ``revision'' or a ``rev''.
jerojasro@343 231
jerojasro@343 232 While it doesn't matter what \emph{word} you use to refer to the
jerojasro@343 233 concept of ``a~changeset'', the \emph{identifier} that you use to
jerojasro@343 234 refer to ``a~\emph{specific} changeset'' is of great importance.
jerojasro@343 235 Recall that the \texttt{changeset} field in the output from
jerojasro@343 236 \hgcmd{log} identifies a changeset using both a number and a
jerojasro@343 237 hexadecimal string.
jerojasro@343 238 \begin{itemize}
jerojasro@343 239 \item The revision number is \emph{only valid in that repository},
jerojasro@343 240 \item while the hex string is the \emph{permanent, unchanging
jerojasro@343 241 identifier} that will always identify that exact changeset in
jerojasro@343 242 \emph{every} copy of the repository.
jerojasro@343 243 \end{itemize}
jerojasro@343 244 This distinction is important. If you send someone an email talking
jerojasro@343 245 about ``revision~33'', there's a high likelihood that their
jerojasro@343 246 revision~33 will \emph{not be the same} as yours. The reason for this
jerojasro@343 247 is that a revision number depends on the order in which changes
jerojasro@343 248 arrived in a repository, and there is no guarantee that the same
jerojasro@343 249 changes will happen in the same order in different repositories.
jerojasro@343 250 Three changes $a,b,c$ can easily appear in one repository as $0,1,2$,
jerojasro@343 251 while in another as $1,0,2$.
jerojasro@343 252
jerojasro@343 253 Mercurial uses revision numbers purely as a convenient shorthand. If
jerojasro@343 254 you need to discuss a changeset with someone, or make a record of a
jerojasro@343 255 changeset for some other reason (for example, in a bug report), use
jerojasro@343 256 the hexadecimal identifier.
jerojasro@343 257
jerojasro@343 258 \subsection{Viewing specific revisions}
jerojasro@343 259
jerojasro@343 260 To narrow the output of \hgcmd{log} down to a single revision, use the
jerojasro@343 261 \hgopt{log}{-r} (or \hgopt{log}{--rev}) option. You can use either a
jerojasro@343 262 revision number or a long-form changeset identifier, and you can
jerojasro@343 263 provide as many revisions as you want. \interaction{tour.log-r}
jerojasro@343 264
jerojasro@343 265 If you want to see the history of several revisions without having to
jerojasro@343 266 list each one, you can use \emph{range notation}; this lets you
jerojasro@343 267 express the idea ``I want all revisions between $a$ and $b$,
jerojasro@343 268 inclusive''.
jerojasro@343 269 \interaction{tour.log.range}
jerojasro@343 270 Mercurial also honours the order in which you specify revisions, so
jerojasro@343 271 \hgcmdargs{log}{-r 2:4} prints $2,3,4$ while \hgcmdargs{log}{-r 4:2}
jerojasro@343 272 prints $4,3,2$.
jerojasro@343 273
jerojasro@343 274 \subsection{More detailed information}
jerojasro@343 275
jerojasro@343 276 While the summary information printed by \hgcmd{log} is useful if you
jerojasro@343 277 already know what you're looking for, you may need to see a complete
jerojasro@343 278 description of the change, or a list of the files changed, if you're
jerojasro@343 279 trying to decide whether a changeset is the one you're looking for.
jerojasro@343 280 The \hgcmd{log} command's \hggopt{-v} (or \hggopt{--verbose})
jerojasro@343 281 option gives you this extra detail.
jerojasro@343 282 \interaction{tour.log-v}
jerojasro@343 283
jerojasro@343 284 If you want to see both the description and content of a change, add
jerojasro@343 285 the \hgopt{log}{-p} (or \hgopt{log}{--patch}) option. This displays
jerojasro@343 286 the content of a change as a \emph{unified diff} (if you've never seen
jerojasro@343 287 a unified diff before, see section~\ref{sec:mq:patch} for an overview).
jerojasro@343 288 \interaction{tour.log-vp}
jerojasro@343 289
jerojasro@343 290 \section{All about command options}
jerojasro@343 291
jerojasro@343 292 Let's take a brief break from exploring Mercurial commands to discuss
jerojasro@343 293 a pattern in the way that they work; you may find this useful to keep
jerojasro@343 294 in mind as we continue our tour.
jerojasro@343 295
jerojasro@343 296 Mercurial has a consistent and straightforward approach to dealing
jerojasro@343 297 with the options that you can pass to commands. It follows the
jerojasro@343 298 conventions for options that are common to modern Linux and Unix
jerojasro@343 299 systems.
jerojasro@343 300 \begin{itemize}
jerojasro@343 301 \item Every option has a long name. For example, as we've already
jerojasro@343 302 seen, the \hgcmd{log} command accepts a \hgopt{log}{--rev} option.
jerojasro@343 303 \item Most options have short names, too. Instead of
jerojasro@343 304 \hgopt{log}{--rev}, we can use \hgopt{log}{-r}. (The reason that
jerojasro@343 305 some options don't have short names is that the options in question
jerojasro@343 306 are rarely used.)
jerojasro@343 307 \item Long options start with two dashes (e.g.~\hgopt{log}{--rev}),
jerojasro@343 308 while short options start with one (e.g.~\hgopt{log}{-r}).
jerojasro@343 309 \item Option naming and usage is consistent across commands. For
jerojasro@343 310 example, every command that lets you specify a changeset~ID or
jerojasro@343 311 revision number accepts both \hgopt{log}{-r} and \hgopt{log}{--rev}
jerojasro@343 312 arguments.
jerojasro@343 313 \end{itemize}
jerojasro@343 314 In the examples throughout this book, I use short options instead of
jerojasro@343 315 long. This just reflects my own preference, so don't read anything
jerojasro@343 316 significant into it.
jerojasro@343 317
jerojasro@343 318 Most commands that print output of some kind will print more output
jerojasro@343 319 when passed a \hggopt{-v} (or \hggopt{--verbose}) option, and less
jerojasro@343 320 when passed \hggopt{-q} (or \hggopt{--quiet}).
jerojasro@343 321
jerojasro@343 322 \section{Making and reviewing changes}
jerojasro@343 323
jerojasro@343 324 Now that we have a grasp of viewing history in Mercurial, let's take a
jerojasro@343 325 look at making some changes and examining them.
jerojasro@343 326
jerojasro@343 327 The first thing we'll do is isolate our experiment in a repository of
jerojasro@343 328 its own. We use the \hgcmd{clone} command, but we don't need to
jerojasro@343 329 clone a copy of the remote repository. Since we already have a copy
jerojasro@343 330 of it locally, we can just clone that instead. This is much faster
jerojasro@343 331 than cloning over the network, and cloning a local repository uses
jerojasro@343 332 less disk space in most cases, too.
jerojasro@343 333 \interaction{tour.reclone}
jerojasro@343 334 As an aside, it's often good practice to keep a ``pristine'' copy of a
jerojasro@343 335 remote repository around, which you can then make temporary clones of
jerojasro@343 336 to create sandboxes for each task you want to work on. This lets you
jerojasro@343 337 work on multiple tasks in parallel, each isolated from the others
jerojasro@343 338 until it's complete and you're ready to integrate it back. Because
jerojasro@343 339 local clones are so cheap, there's almost no overhead to cloning and
jerojasro@343 340 destroying repositories whenever you want.
jerojasro@343 341
jerojasro@343 342 In our \dirname{my-hello} repository, we have a file
jerojasro@343 343 \filename{hello.c} that contains the classic ``hello, world'' program.
jerojasro@343 344 Let's use the ancient and venerable \command{sed} command to edit this
jerojasro@343 345 file so that it prints a second line of output. (I'm only using
jerojasro@343 346 \command{sed} to do this because it's easy to write a scripted example
jerojasro@343 347 this way. Since you're not under the same constraint, you probably
jerojasro@343 348 won't want to use \command{sed}; simply use your preferred text editor to
jerojasro@343 349 do the same thing.)
jerojasro@343 350 \interaction{tour.sed}
jerojasro@343 351
jerojasro@343 352 Mercurial's \hgcmd{status} command will tell us what Mercurial knows
jerojasro@343 353 about the files in the repository.
jerojasro@343 354 \interaction{tour.status}
jerojasro@343 355 The \hgcmd{status} command prints no output for some files, but a line
jerojasro@343 356 starting with ``\texttt{M}'' for \filename{hello.c}. Unless you tell
jerojasro@343 357 it to, \hgcmd{status} will not print any output for files that have
jerojasro@343 358 not been modified.
jerojasro@343 359
jerojasro@343 360 The ``\texttt{M}'' indicates that Mercurial has noticed that we
jerojasro@343 361 modified \filename{hello.c}. We didn't need to \emph{inform}
jerojasro@343 362 Mercurial that we were going to modify the file before we started, or
jerojasro@343 363 that we had modified the file after we were done; it was able to
jerojasro@343 364 figure this out itself.
jerojasro@343 365
jerojasro@343 366 It's a little bit helpful to know that we've modified
jerojasro@343 367 \filename{hello.c}, but we might prefer to know exactly \emph{what}
jerojasro@343 368 changes we've made to it. To do this, we use the \hgcmd{diff}
jerojasro@343 369 command.
jerojasro@343 370 \interaction{tour.diff}
jerojasro@343 371
jerojasro@343 372 \section{Recording changes in a new changeset}
jerojasro@343 373
jerojasro@343 374 We can modify files, build and test our changes, and use
jerojasro@343 375 \hgcmd{status} and \hgcmd{diff} to review our changes, until we're
jerojasro@343 376 satisfied with what we've done and arrive at a natural stopping point
jerojasro@343 377 where we want to record our work in a new changeset.
jerojasro@343 378
jerojasro@343 379 The \hgcmd{commit} command lets us create a new changeset; we'll
jerojasro@343 380 usually refer to this as ``making a commit'' or ``committing''.
jerojasro@343 381
jerojasro@343 382 \subsection{Setting up a username}
jerojasro@343 383
jerojasro@343 384 When you try to run \hgcmd{commit} for the first time, it is not
jerojasro@343 385 guaranteed to succeed. Mercurial records your name and address with
jerojasro@343 386 each change that you commit, so that you and others will later be able
jerojasro@343 387 to tell who made each change. Mercurial tries to automatically figure
jerojasro@343 388 out a sensible username to commit the change with. It will attempt
jerojasro@343 389 each of the following methods, in order:
jerojasro@343 390 \begin{enumerate}
jerojasro@343 391 \item If you specify a \hgopt{commit}{-u} option to the \hgcmd{commit}
jerojasro@343 392 command on the command line, followed by a username, this is always
jerojasro@343 393 given the highest precedence.
jerojasro@343 394 \item If you have set the \envar{HGUSER} environment variable, this is
jerojasro@343 395 checked next.
jerojasro@343 396 \item If you create a file in your home directory called
jerojasro@343 397 \sfilename{.hgrc}, with a \rcitem{ui}{username} entry, that will be
jerojasro@343 398 used next. To see what the contents of this file should look like,
jerojasro@343 399 refer to section~\ref{sec:tour-basic:username} below.
jerojasro@343 400 \item If you have set the \envar{EMAIL} environment variable, this
jerojasro@343 401 will be used next.
jerojasro@343 402 \item Mercurial will query your system to find out your local user
jerojasro@343 403 name and host name, and construct a username from these components.
jerojasro@343 404 Since this often results in a username that is not very useful, it
jerojasro@343 405 will print a warning if it has to do this.
jerojasro@343 406 \end{enumerate}
jerojasro@343 407 If all of these mechanisms fail, Mercurial will fail, printing an
jerojasro@343 408 error message. In this case, it will not let you commit until you set
jerojasro@343 409 up a username.
jerojasro@343 410
jerojasro@343 411 You should think of the \envar{HGUSER} environment variable and the
jerojasro@343 412 \hgopt{commit}{-u} option to the \hgcmd{commit} command as ways to
jerojasro@343 413 \emph{override} Mercurial's default selection of username. For normal
jerojasro@343 414 use, the simplest and most robust way to set a username for yourself
jerojasro@343 415 is by creating a \sfilename{.hgrc} file; see below for details.
jerojasro@343 416
jerojasro@343 417 \subsubsection{Creating a Mercurial configuration file}
jerojasro@343 418 \label{sec:tour-basic:username}
jerojasro@343 419
jerojasro@343 420 To set a user name, use your favourite editor to create a file called
jerojasro@343 421 \sfilename{.hgrc} in your home directory. Mercurial will use this
jerojasro@343 422 file to look up your personalised configuration settings. The initial
jerojasro@343 423 contents of your \sfilename{.hgrc} should look like this.
jerojasro@343 424 \begin{codesample2}
jerojasro@343 425 # This is a Mercurial configuration file.
jerojasro@343 426 [ui]
jerojasro@343 427 username = Firstname Lastname <email.address@domain.net>
jerojasro@343 428 \end{codesample2}
jerojasro@343 429 The ``\texttt{[ui]}'' line begins a \emph{section} of the config file,
jerojasro@343 430 so you can read the ``\texttt{username = ...}'' line as meaning ``set
jerojasro@343 431 the value of the \texttt{username} item in the \texttt{ui} section''.
jerojasro@343 432 A section continues until a new section begins, or the end of the
jerojasro@343 433 file. Mercurial ignores empty lines and treats any text from
jerojasro@343 434 ``\texttt{\#}'' to the end of a line as a comment.
jerojasro@343 435
jerojasro@343 436 \subsubsection{Choosing a user name}
jerojasro@343 437
jerojasro@343 438 You can use any text you like as the value of the \texttt{username}
jerojasro@343 439 config item, since this information is for reading by other people,
jerojasro@343 440 but for interpreting by Mercurial. The convention that most people
jerojasro@343 441 follow is to use their name and email address, as in the example
jerojasro@343 442 above.
jerojasro@343 443
jerojasro@343 444 \begin{note}
jerojasro@343 445 Mercurial's built-in web server obfuscates email addresses, to make
jerojasro@343 446 it more difficult for the email harvesting tools that spammers use.
jerojasro@343 447 This reduces the likelihood that you'll start receiving more junk
jerojasro@343 448 email if you publish a Mercurial repository on the web.
jerojasro@343 449 \end{note}
jerojasro@343 450
jerojasro@343 451 \subsection{Writing a commit message}
jerojasro@343 452
jerojasro@343 453 When we commit a change, Mercurial drops us into a text editor, to
jerojasro@343 454 enter a message that will describe the modifications we've made in
jerojasro@343 455 this changeset. This is called the \emph{commit message}. It will be
jerojasro@343 456 a record for readers of what we did and why, and it will be printed by
jerojasro@343 457 \hgcmd{log} after we've finished committing.
jerojasro@343 458 \interaction{tour.commit}
jerojasro@343 459
jerojasro@343 460 The editor that the \hgcmd{commit} command drops us into will contain
jerojasro@343 461 an empty line, followed by a number of lines starting with
jerojasro@343 462 ``\texttt{HG:}''.
jerojasro@343 463 \begin{codesample2}
jerojasro@343 464 \emph{empty line}
jerojasro@343 465 HG: changed hello.c
jerojasro@343 466 \end{codesample2}
jerojasro@343 467 Mercurial ignores the lines that start with ``\texttt{HG:}''; it uses
jerojasro@343 468 them only to tell us which files it's recording changes to. Modifying
jerojasro@343 469 or deleting these lines has no effect.
jerojasro@343 470
jerojasro@343 471 \subsection{Writing a good commit message}
jerojasro@343 472
jerojasro@343 473 Since \hgcmd{log} only prints the first line of a commit message by
jerojasro@343 474 default, it's best to write a commit message whose first line stands
jerojasro@343 475 alone. Here's a real example of a commit message that \emph{doesn't}
jerojasro@343 476 follow this guideline, and hence has a summary that is not readable.
jerojasro@343 477 \begin{codesample2}
jerojasro@343 478 changeset: 73:584af0e231be
jerojasro@343 479 user: Censored Person <censored.person@example.org>
jerojasro@343 480 date: Tue Sep 26 21:37:07 2006 -0700
jerojasro@343 481 summary: include buildmeister/commondefs. Add an exports and install
jerojasro@343 482 \end{codesample2}
jerojasro@343 483
jerojasro@343 484 As far as the remainder of the contents of the commit message are
jerojasro@343 485 concerned, there are no hard-and-fast rules. Mercurial itself doesn't
jerojasro@343 486 interpret or care about the contents of the commit message, though
jerojasro@343 487 your project may have policies that dictate a certain kind of
jerojasro@343 488 formatting.
jerojasro@343 489
jerojasro@343 490 My personal preference is for short, but informative, commit messages
jerojasro@343 491 that tell me something that I can't figure out with a quick glance at
jerojasro@343 492 the output of \hgcmdargs{log}{--patch}.
jerojasro@343 493
jerojasro@343 494 \subsection{Aborting a commit}
jerojasro@343 495
jerojasro@343 496 If you decide that you don't want to commit while in the middle of
jerojasro@343 497 editing a commit message, simply exit from your editor without saving
jerojasro@343 498 the file that it's editing. This will cause nothing to happen to
jerojasro@343 499 either the repository or the working directory.
jerojasro@343 500
jerojasro@343 501 If we run the \hgcmd{commit} command without any arguments, it records
jerojasro@343 502 all of the changes we've made, as reported by \hgcmd{status} and
jerojasro@343 503 \hgcmd{diff}.
jerojasro@343 504
jerojasro@343 505 \subsection{Admiring our new handiwork}
jerojasro@343 506
jerojasro@343 507 Once we've finished the commit, we can use the \hgcmd{tip} command to
jerojasro@343 508 display the changeset we just created. This command produces output
jerojasro@343 509 that is identical to \hgcmd{log}, but it only displays the newest
jerojasro@343 510 revision in the repository.
jerojasro@343 511 \interaction{tour.tip}
jerojasro@343 512 We refer to the newest revision in the repository as the tip revision,
jerojasro@343 513 or simply the tip.
jerojasro@343 514
jerojasro@343 515 \section{Sharing changes}
jerojasro@343 516
jerojasro@343 517 We mentioned earlier that repositories in Mercurial are
jerojasro@343 518 self-contained. This means that the changeset we just created exists
jerojasro@343 519 only in our \dirname{my-hello} repository. Let's look at a few ways
jerojasro@343 520 that we can propagate this change into other repositories.
jerojasro@343 521
jerojasro@343 522 \subsection{Pulling changes from another repository}
jerojasro@343 523 \label{sec:tour:pull}
jerojasro@343 524
jerojasro@343 525 To get started, let's clone our original \dirname{hello} repository,
jerojasro@343 526 which does not contain the change we just committed. We'll call our
jerojasro@343 527 temporary repository \dirname{hello-pull}.
jerojasro@343 528 \interaction{tour.clone-pull}
jerojasro@343 529
jerojasro@343 530 We'll use the \hgcmd{pull} command to bring changes from
jerojasro@343 531 \dirname{my-hello} into \dirname{hello-pull}. However, blindly
jerojasro@343 532 pulling unknown changes into a repository is a somewhat scary
jerojasro@343 533 prospect. Mercurial provides the \hgcmd{incoming} command to tell us
jerojasro@343 534 what changes the \hgcmd{pull} command \emph{would} pull into the
jerojasro@343 535 repository, without actually pulling the changes in.
jerojasro@343 536 \interaction{tour.incoming}
jerojasro@343 537 (Of course, someone could cause more changesets to appear in the
jerojasro@343 538 repository that we ran \hgcmd{incoming} in, before we get a chance to
jerojasro@343 539 \hgcmd{pull} the changes, so that we could end up pulling changes that we
jerojasro@343 540 didn't expect.)
jerojasro@343 541
jerojasro@343 542 Bringing changes into a repository is a simple matter of running the
jerojasro@343 543 \hgcmd{pull} command, and telling it which repository to pull from.
jerojasro@343 544 \interaction{tour.pull}
jerojasro@343 545 As you can see from the before-and-after output of \hgcmd{tip}, we
jerojasro@343 546 have successfully pulled changes into our repository. There remains
jerojasro@343 547 one step before we can see these changes in the working directory.
jerojasro@343 548
jerojasro@343 549 \subsection{Updating the working directory}
jerojasro@343 550
jerojasro@343 551 We have so far glossed over the relationship between a repository and
jerojasro@343 552 its working directory. The \hgcmd{pull} command that we ran in
jerojasro@343 553 section~\ref{sec:tour:pull} brought changes into the repository, but
jerojasro@343 554 if we check, there's no sign of those changes in the working
jerojasro@343 555 directory. This is because \hgcmd{pull} does not (by default) touch
jerojasro@343 556 the working directory. Instead, we use the \hgcmd{update} command to
jerojasro@343 557 do this.
jerojasro@343 558 \interaction{tour.update}
jerojasro@343 559
jerojasro@343 560 It might seem a bit strange that \hgcmd{pull} doesn't update the
jerojasro@343 561 working directory automatically. There's actually a good reason for
jerojasro@343 562 this: you can use \hgcmd{update} to update the working directory to
jerojasro@343 563 the state it was in at \emph{any revision} in the history of the
jerojasro@343 564 repository. If you had the working directory updated to an old
jerojasro@343 565 revision---to hunt down the origin of a bug, say---and ran a
jerojasro@343 566 \hgcmd{pull} which automatically updated the working directory to a
jerojasro@343 567 new revision, you might not be terribly happy.
jerojasro@343 568
jerojasro@343 569 However, since pull-then-update is such a common thing to do,
jerojasro@343 570 Mercurial lets you combine the two by passing the \hgopt{pull}{-u}
jerojasro@343 571 option to \hgcmd{pull}.
jerojasro@343 572 \begin{codesample2}
jerojasro@343 573 hg pull -u
jerojasro@343 574 \end{codesample2}
jerojasro@343 575 If you look back at the output of \hgcmd{pull} in
jerojasro@343 576 section~\ref{sec:tour:pull} when we ran it without \hgopt{pull}{-u},
jerojasro@343 577 you can see that it printed a helpful reminder that we'd have to take
jerojasro@343 578 an explicit step to update the working directory:
jerojasro@343 579 \begin{codesample2}
jerojasro@343 580 (run 'hg update' to get a working copy)
jerojasro@343 581 \end{codesample2}
jerojasro@343 582
jerojasro@343 583 To find out what revision the working directory is at, use the
jerojasro@343 584 \hgcmd{parents} command.
jerojasro@343 585 \interaction{tour.parents}
jerojasro@343 586 If you look back at figure~\ref{fig:tour-basic:history}, you'll see
jerojasro@343 587 arrows connecting each changeset. The node that the arrow leads
jerojasro@343 588 \emph{from} in each case is a parent, and the node that the arrow
jerojasro@343 589 leads \emph{to} is its child. The working directory has a parent in
jerojasro@343 590 just the same way; this is the changeset that the working directory
jerojasro@343 591 currently contains.
jerojasro@343 592
jerojasro@343 593 To update the working directory to a particular revision, give a
jerojasro@343 594 revision number or changeset~ID to the \hgcmd{update} command.
jerojasro@343 595 \interaction{tour.older}
jerojasro@343 596 If you omit an explicit revision, \hgcmd{update} will update to the
jerojasro@343 597 tip revision, as shown by the second call to \hgcmd{update} in the
jerojasro@343 598 example above.
jerojasro@343 599
jerojasro@343 600 \subsection{Pushing changes to another repository}
jerojasro@343 601
jerojasro@343 602 Mercurial lets us push changes to another repository, from the
jerojasro@343 603 repository we're currently visiting. As with the example of
jerojasro@343 604 \hgcmd{pull} above, we'll create a temporary repository to push our
jerojasro@343 605 changes into.
jerojasro@343 606 \interaction{tour.clone-push}
jerojasro@343 607 The \hgcmd{outgoing} command tells us what changes would be pushed
jerojasro@343 608 into another repository.
jerojasro@343 609 \interaction{tour.outgoing}
jerojasro@343 610 And the \hgcmd{push} command does the actual push.
jerojasro@343 611 \interaction{tour.push}
jerojasro@343 612 As with \hgcmd{pull}, the \hgcmd{push} command does not update the
jerojasro@343 613 working directory in the repository that it's pushing changes into.
jerojasro@343 614 (Unlike \hgcmd{pull}, \hgcmd{push} does not provide a \texttt{-u}
jerojasro@343 615 option that updates the other repository's working directory.)
jerojasro@343 616
jerojasro@343 617 What happens if we try to pull or push changes and the receiving
jerojasro@343 618 repository already has those changes? Nothing too exciting.
jerojasro@343 619 \interaction{tour.push.nothing}
jerojasro@343 620
jerojasro@343 621 \subsection{Sharing changes over a network}
jerojasro@343 622
jerojasro@343 623 The commands we have covered in the previous few sections are not
jerojasro@343 624 limited to working with local repositories. Each works in exactly the
jerojasro@343 625 same fashion over a network connection; simply pass in a URL instead
jerojasro@343 626 of a local path.
jerojasro@343 627 \interaction{tour.outgoing.net}
jerojasro@343 628 In this example, we can see what changes we could push to the remote
jerojasro@343 629 repository, but the repository is understandably not set up to let
jerojasro@343 630 anonymous users push to it.
jerojasro@343 631 \interaction{tour.push.net}
jerojasro@343 632
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