<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Chapter 9. Finding and fixing mistakes</title><link rel="stylesheet" href="/support/styles.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.74.3"><link rel="home" href="index.html" title="Mercurial: The Definitive Guide"><link rel="up" href="index.html" title="Mercurial: The Definitive Guide"><link rel="prev" href="managing-releases-and-branchy-development.html" title="Chapter 8. Managing releases and branchy development"><link rel="next" href="handling-repository-events-with-hooks.html" title="Chapter 10. Handling repository events with hooks"><link rel="alternate" type="application/atom+xml" title="Comments" href="/feeds/comments/"><link rel="shortcut icon" type="image/png" href="/support/figs/favicon.png"><script type="text/javascript" src="/support/jquery-min.js"></script><script type="text/javascript" src="/support/form.js"></script><script type="text/javascript" src="/support/hsbook.js"></script></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 14. Adding functionality with extensions</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="advanced-uses-of-mercurial-queues.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="migrating-to-mercurial.html">Next</a></td></tr></table><hr></div><div class="chapter" title="Chapter 14. Adding functionality with extensions"><div class="titlepage"><div><div><h2 class="title"><a name="chap:hgext"></a>Chapter 14. Adding functionality with extensions</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="adding-functionality-with-extensions.html#sec:hgext:inotify">14.1. Improve performance with the <code class="literal">inotify</code> extension</a></span></dt><dt><span class="sect1"><a href="adding-functionality-with-extensions.html#sec:hgext:extdiff">14.2. Flexible diff support with the <code class="literal">extdiff</code> extension</a></span></dt><dd><dl><dt><span class="sect2"><a href="adding-functionality-with-extensions.html#id3071699">14.2.1. Defining command aliases</a></span></dt></dl></dd><dt><span class="sect1"><a href="adding-functionality-with-extensions.html#sec:hgext:transplant">14.3. Cherrypicking changes with the <code class="literal">transplant</code> extension</a></span></dt><dt><span class="sect1"><a href="adding-functionality-with-extensions.html#sec:hgext:patchbomb">14.4. Send changes via email with the <code class="literal">patchbomb</code> extension</a></span></dt><dd><dl><dt><span class="sect2"><a href="adding-functionality-with-extensions.html#id3072184">14.4.1. Changing the behavior of patchbombs</a></span></dt></dl></dd></dl></div><p id="x_4fe"></a>While the core of Mercurial is quite complete from a functionality standpoint, it's deliberately shorn of fancy features. This approach of preserving simplicity keeps the software easy to deal with for both maintainers and users.</p><p id="x_4ff"></a>However, Mercurial doesn't box you in with an inflexible command set: you can add features to it as <span class="emphasis"><em>extensions</em></span> (sometimes known as <span class="emphasis"><em>plugins</em></span>). We've already discussed a few of these extensions in earlier chapters.</p><p id="x_546" id="x_546"></a>When you provide a directory name, Mercurial will interpret this as “<span class="quote">operate on every file in this directory and its subdirectories</span>”. Mercurial traverses the files and subdirectories in a directory in alphabetical order. When it encounters a subdirectory, it will traverse that subdirectory before continuing with the current directory.</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p id="x_500"></a><a class="xref" href="a-tour-of-mercurial-merging-work.html#sec:tour-merge:fetch" title="3.3. Simplifying the pull-merge-commit sequence">Section 3.3, “Simplifying the pull-merge-commit sequence”</a> covers the <code class="literal">fetch</code> extension; this combines pulling new changes and merging them with local changes into a single command, <span class="command"><strong>fetch</strong></span>.</p></li><li class="listitem"><p id="x_501"></a>In <a class="xref" href="handling-repository-events-with-hooks.html" title="Chapter 10. Handling repository events with hooks">Chapter 10, <i>Handling repository events with hooks</i></a>, we covered several extensions that are useful for hook-related functionality: <code class="literal">acl</code> adds access control lists; <code class="literal">bugzilla</code> adds integration with the Bugzilla bug tracking system; and <code class="literal">notify</code> sends notification emails on new changes.</p></li><li class="listitem"><p id="x_502"></a>The Mercurial Queues patch management extension is so invaluable that it merits two chapters and an appendix all to itself. <a class="xref" href="managing-change-with-mercurial-queues.html" title="Chapter 12. Managing change with Mercurial Queues">Chapter 12, <i>Managing change with Mercurial Queues</i></a> covers the basics; <a class="xref" href="advanced-uses-of-mercurial-queues.html" title="Chapter 13. Advanced uses of Mercurial Queues">Chapter 13, <i>Advanced uses of Mercurial Queues</i></a> discusses advanced topics; and <a class="xref" href="mercurial-queues-reference.html" title="Appendix B. Mercurial Queues reference">Appendix B, <i>Mercurial Queues reference</i></a> goes into detail on each command.</p></li></ul></div><p id="x_503"></a>In this chapter, we'll cover some of the other extensions that are available for Mercurial, and briefly touch on some of the machinery you'll need to know about if you want to write an extension of your own.</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p id="x_504"></a>In <a class="xref" href="adding-functionality-with-extensions.html#sec:hgext:inotify" title="14.1. Improve performance with the inotify extension">Section 14.1, “Improve performance with the <code class="literal">inotify</code> extension”</a>, we'll discuss the possibility of <span class="emphasis"><em>huge</em></span> performance improvements using the <code class="literal">inotify</code> extension.</p></li></ul></div><div class="sect1" title="14.1. Improve performance with the inotify extension"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="sec:hgext:inotify"></a>14.1. Improve performance with the <code class="literal">inotify</code> extension</h2></div></div></div><p id="x_505"></a>Are you interested in having some of the most common Mercurial operations run as much as a hundred times faster? Read on!</p><p id="x_506"></a>Mercurial has great performance under normal circumstances. For example, when you run the <span class="command"><strong>hg status</strong></span> command, Mercurial has to scan almost every directory and file in your repository so that it can display file status. Many other Mercurial commands need to do the same work behind the scenes; for example, the <span class="command"><strong>hg diff</strong></span> command uses the status machinery to avoid doing an expensive comparison operation on files that obviously haven't changed.</p><p id="x_507"></a>Because obtaining file status is crucial to good performance, the authors of Mercurial have optimised this code to within an inch of its life. However, there's no avoiding the fact that when you run <span class="command"><strong>hg status</strong></span>, Mercurial is going to have to perform at least one expensive system call for each managed file to determine whether it's changed since the last time Mercurial checked. For a sufficiently large repository, this can take a long time.</p><p id="x_508"></a>To put a number on the magnitude of this effect, I created a repository containing 150,000 managed files. I timed <span class="command"><strong>hg status</strong></span> as taking ten seconds to run, even when <span class="emphasis"><em>none</em></span> of those files had been modified.</p><p id="x_509"></a>Many modern operating systems contain a file notification facility. If a program signs up to an appropriate service, the operating system will notify it every time a file of interest is created, modified, or deleted. On Linux systems, the kernel component that does this is called <code class="literal">inotify</code>.</p><p id="x_50a"></a>Mercurial's <code class="literal">inotify</code> extension talks to the kernel's <code class="literal">inotify</code> component to optimise <span class="command"><strong>hg status</strong></span> commands. The extension has two components. A daemon sits in the background and receives notifications from the <code class="literal">inotify</code> subsystem. It also listens for connections from a regular Mercurial command. The extension modifies Mercurial's behavior so that instead of scanning the filesystem, it queries the daemon. Since the daemon has perfect information about the state of the repository, it can respond with a result instantaneously, avoiding the need to scan every directory and file in the repository.</p><p id="x_50b"></a>Recall the ten seconds that I measured plain Mercurial as taking to run <span class="command"><strong>hg status</strong></span> on a 150,000 file repository. With the <code class="literal">inotify</code> extension enabled, the time dropped to 0.1 seconds, a factor of <span class="emphasis"><em>one hundred</em></span> faster.</p><p id="x_50c"></a>Before we continue, please pay attention to some caveats.</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p id="x_50d"></a>The <code class="literal">inotify</code> extension is Linux-specific. Because it interfaces directly to the Linux kernel's <code class="literal">inotify</code> subsystem, it does not work on other operating systems.</p></li><li class="listitem"><p id="x_50e"></a>It should work on any Linux distribution that was released after early 2005. Older distributions are likely to have a kernel that lacks <code class="literal">inotify</code>, or a version of <code class="literal">glibc</code> that does not have the necessary interfacing support.</p></li><li class="listitem"><p id="x_50f"></a>Not all filesystems are suitable for use with the <code class="literal">inotify</code> extension. Network filesystems such as NFS are a non-starter, for example, particularly if you're running Mercurial on several systems, all mounting the same network filesystem. The kernel's <code class="literal">inotify</code> system has no way of knowing about changes made on another system. Most local filesystems (e.g. ext3, XFS, ReiserFS) should work fine.</p></li></ul></div><p id="x_510"></a>The <code class="literal">inotify</code> extension is not yet shipped with Mercurial as of May 2007, so it's a little more involved to set up than other extensions. But the performance improvement is worth it!</p><p id="x_511"></a>The extension currently comes in two parts: a set of patches to the Mercurial source code, and a library of Python bindings to the <code class="literal">inotify</code> subsystem.</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="figs/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p id="x_512"></a> There are <span class="emphasis"><em>two</em></span> Python <code class="literal">inotify</code> binding libraries. One of them is called <code class="literal">pyinotify</code>, and is packaged by some Linux distributions as <code class="literal">python-inotify</code>. This is <span class="emphasis"><em>not</em></span> the one you'll need, as it is too buggy and inefficient to be practical.</p></td></tr></table></div><p id="x_513"></a>To get going, it's best to already have a functioning copy of Mercurial installed.</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Note"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="figs/note.png"></td><th align="left">Note</th></tr><tr><td align="left" valign="top"><p id="x_514"></a> If you follow the instructions below, you'll be <span class="emphasis"><em>replacing</em></span> and overwriting any existing installation of Mercurial that you might already have, using the latest <span class="quote">“<span class="quote">bleeding edge</span>”</span> Mercurial code. Don't say you weren't warned!</p></td></tr></table></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p id="x_515"></a>Clone the Python <code class="literal">inotify</code> binding repository. Build and install it.</p><pre class="programlisting">hg clone http://hg.kublai.com/python/inotifycd inotifypython setup.py build --forcesudo python setup.py install --skip-build</pre></li><li class="listitem"><p id="x_516"></a>Clone the <code class="filename">crew</code> Mercurial repository. Clone the <code class="literal">inotify</code> patch repository so that Mercurial Queues will be able to apply patches to your cope of the <code class="filename">crew</code> repository.</p><pre class="programlisting">hg clone http://hg.intevation.org/mercurial/crewhg clone crew inotifyhg clone http://hg.kublai.com/mercurial/patches/inotify inotify/.hg/patches</pre></li><li class="listitem"><p id="x_517"></a>Make sure that you have the Mercurial Queues extension, <code class="literal">mq</code>, enabled. If you've never used MQ, read <a class="xref" href="managing-change-with-mercurial-queues.html#sec:mq:start" title="12.5. Getting started with Mercurial Queues">Section 12.5, “Getting started with Mercurial Queues”</a> to get started quickly.</p></li><li class="listitem"><p id="x_518"></a>Go into the <code class="filename">inotify</code> repo, and apply all of the <code class="literal">inotify</code> patches using the <code class="option">hg -a</code> option to the <span class="command"><strong>qpush</strong></span> command.</p><pre class="programlisting">cd inotifyhg qpush -a</pre></li><li class="listitem"><p id="x_519"></a> If you get an error message from <span class="command"><strong>qpush</strong></span>, you should not continue. Instead, ask for help.</p></li><li class="listitem"><p id="x_51a"></a>Build and install the patched version of Mercurial.</p><pre class="programlisting">python setup.py build --forcesudo python setup.py install --skip-build</pre></li></ol></div><p id="x_51b"></a>Once you've build a suitably patched version of Mercurial, all you need to do to enable the <code class="literal">inotify</code> extension is add an entry to your <code class="filename">~/.hgrc</code>.</p><pre class="programlisting">[extensions] inotify =</pre><p id="x_51c"></a>When the <code class="literal">inotify</code> extension is enabled, Mercurial will automatically and transparently start the status daemon the first time you run a command that needs status in a repository. It runs one status daemon per repository.</p><p id="x_51d"></a>The status daemon is started silently, and runs in the background. If you look at a list of running processes after you've enabled the <code class="literal">inotify</code> extension and run a few commands in different repositories, you'll thus see a few <code class="literal">hg</code> processes sitting around, waiting for updates from the kernel and queries from Mercurial.</p><p id="x_51e"></a>The first time you run a Mercurial command in a repository when you have the <code class="literal">inotify</code> extension enabled, it will run with about the same performance as a normal Mercurial command. This is because the status daemon needs to perform a normal status scan so that it has a baseline against which to apply later updates from the kernel. However, <span class="emphasis"><em>every</em></span> subsequent command that does any kind of status check should be noticeably faster on repositories of even fairly modest size. Better yet, the bigger your repository is, the greater a performance advantage you'll see. The <code class="literal">inotify</code> daemon makes status operations almost instantaneous on repositories of all sizes!</p><p id="x_51f"></a>If you like, you can manually start a status daemon using the <span class="command"><strong>inserve</strong></span> command. This gives you slightly finer control over how the daemon ought to run. This command will of course only be available when the <code class="literal">inotify</code> extension is enabled.</p><p id="x_520"></a>When you're using the <code class="literal">inotify</code> extension, you should notice <span class="emphasis"><em>no difference at all</em></span> in Mercurial's behavior, with the sole exception of status-related commands running a whole lot faster than they used to. You should specifically expect that commands will not print different output; neither should they give different results. If either of these situations occurs, please report a bug.</p></div><div class="sect1" title="14.2. Flexible diff support with the extdiff extension"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="sec:hgext:extdiff"></a>14.2. Flexible diff support with the <code class="literal">extdiff</code> extension</h2></div></div></div><p id="x_521"></a>Mercurial's built-in <span class="command"><strong>hg diff</strong></span> command outputs plaintext unified diffs.</p><pre class="screen"><code class="prompt">$</code> <strong class="userinput"><code>hg diff</code></strong>diff -r 80997726a0ea myfile--- a/myfile Wed Jan 06 06:50:18 2010 +0000+++ b/myfile Wed Jan 06 06:50:18 2010 +0000@@ -1,1 +1,2 @@ The first line.+The second line.</pre><p id="x_522"></a>If you would like to use an external tool to display modifications, you'll want to use the <code class="literal">extdiff</code> extension. This will let you use, for example, a graphical diff tool.</p><p id="x_523"></a>The <code class="literal">extdiff</code> extension is bundled with Mercurial, so it's easy to set up. In the <code class="literal">extensions</code> section of your <code class="filename">~/.hgrc</code>, simply add a one-line entry to enable the extension.</p><pre class="programlisting">[extensions]extdiff =</pre><p id="x_524"></a>This introduces a command named <span class="command"><strong>extdiff</strong></span>, which by default uses your system's <span class="command"><strong>diff</strong></span> command to generate a unified diff in the same form as the built-in <span class="command"><strong>hg diff</strong></span> command.</p><pre class="screen"><code class="prompt">$</code> <strong class="userinput"><code>hg extdiff</code></strong>--- a.80997726a0ea/myfile 2010-01-06 06:50:18.613674526 +0000+++ /tmp/extdiffNErQlu/a/myfile 2010-01-06 06:50:18.437687076 +0000@@ -1 +1,2 @@ The first line.+The second line.</pre><p id="x_525"></a>The result won't be exactly the same as with the built-in <span class="command"><strong>hg diff</strong></span> variations, because the output of <span class="command"><strong>diff</strong></span> varies from one system to another, even when passed the same options.</p><p id="x_526"></a>As the <span class="quote">“<span class="quote"><code class="literal">making snapshot</code></span>”</span> lines of output above imply, the <span class="command"><strong>extdiff</strong></span> command works by creating two snapshots of your source tree. The first snapshot is of the source revision; the second, of the target revision or working directory. The <span class="command"><strong>extdiff</strong></span> command generates these snapshots in a temporary directory, passes the name of each directory to an external diff viewer, then deletes the temporary directory. For efficiency, it only snapshots the directories and files that have changed between the two revisions.</p><p id="x_527"></a>Snapshot directory names have the same base name as your repository. If your repository path is <code class="filename">/quux/bar/foo</code>, then <code class="filename">foo</code> will be the name of each snapshot directory. Each snapshot directory name has its changeset ID appended, if appropriate. If a snapshot is of revision <code class="literal">a631aca1083f</code>, the directory will be named <code class="filename">foo.a631aca1083f</code>. A snapshot of the working directory won't have a changeset ID appended, so it would just be <code class="filename">foo</code> in this example. To see what this looks like in practice, look again at the <span class="command"><strong>extdiff</strong></span> example above. Notice that the diff has the snapshot directory names embedded in its header.</p><p id="x_528"></a>The <span class="command"><strong>extdiff</strong></span> command accepts two important options. The <code class="option">hg -p</code> option lets you choose a program to view differences with, instead of <span class="command"><strong>diff</strong></span>. With the <code class="option">hg -o</code> option, you can change the options that <span class="command"><strong>extdiff</strong></span> passes to the program (by default, these options are <span class="quote">“<span class="quote"><code class="literal">-Npru</code></span>”</span>, which only make sense if you're running <span class="command"><strong>diff</strong></span>). In other respects, the <span class="command"><strong>extdiff</strong></span> command acts similarly to the built-in <span class="command"><strong>hg diff</strong></span> command: you use the same option names, syntax, and arguments to specify the revisions you want, the files you want, and so on.</p><p id="x_529"></a>As an example, here's how to run the normal system <span class="command"><strong>diff</strong></span> command, getting it to generate context diffs (using the <code class="option">-c</code> option) instead of unified diffs, and five lines of context instead of the default three (passing <code class="literal">5</code> as the argument to the <code class="option">-C</code> option).</p><pre class="screen"><code class="prompt">$</code> <strong class="userinput"><code>hg extdiff -o -NprcC5</code></strong>*** a.80997726a0ea/myfile Wed Jan 6 06:50:18 2010--- /tmp/extdiffNErQlu/a/myfile Wed Jan 6 06:50:18 2010****************** 1 ****--- 1,2 ---- The first line.+ The second line.</pre><p id="x_52a"></a>Launching a visual diff tool is just as easy. Here's how to launch the <span class="command"><strong>kdiff3</strong></span> viewer.</p><pre class="programlisting">hg extdiff -p kdiff3 -o</pre><p id="x_52b"></a>If your diff viewing command can't deal with directories, you can easily work around this with a little scripting. For an example of such scripting in action with the <code class="literal">mq</code> extension and the <span class="command"><strong>interdiff</strong></span> command, see <a class="xref" href="advanced-uses-of-mercurial-queues.html#mq-collab:tips:interdiff" title="13.9.2. Viewing the history of a patch">Section 13.9.2, “Viewing the history of a patch”</a>.</p><div class="sect2" title="14.2.1. Defining command aliases"><div class="titlepage"><div><div><h3 class="title"><a name="id3071699"></a>14.2.1. Defining command aliases</h3></div></div></div><p id="x_52c"></a>It can be cumbersome to remember the options to both the <span class="command"><strong>extdiff</strong></span> command and the diff viewer you want to use, so the <code class="literal">extdiff</code> extension lets you define <span class="emphasis"><em>new</em></span> commands that will invoke your diff viewer with exactly the right options.</p><p id="x_52d"></a>All you need to do is edit your <code class="filename">~/.hgrc</code>, and add a section named <code class="literal">extdiff</code>. Inside this section, you can define multiple commands. Here's how to add a <code class="literal">kdiff3</code> command. Once you've defined this, you can type <span class="quote">“<span class="quote"><code class="literal">hg kdiff3</code></span>”</span> and the <code class="literal">extdiff</code> extension will run <span class="command"><strong>kdiff3</strong></span> for you.</p><pre class="programlisting">[extdiff]cmd.kdiff3 =</pre><p id="x_52e"></a>If you leave the right hand side of the definition empty, as above, the <code class="literal">extdiff</code> extension uses the name of the command you defined as the name of the external program to run. But these names don't have to be the same. Here, we define a command named <span class="quote">“<span class="quote"><code class="literal">hg wibble</code></span>”</span>, which runs <span class="command"><strong>kdiff3</strong></span>.</p><pre class="programlisting">[extdiff] cmd.wibble = kdiff3</pre><p id="x_52f"></a>You can also specify the default options that you want to invoke your diff viewing program with. The prefix to use is <span class="quote">“<span class="quote"><code class="literal">opts.</code></span>”</span>, followed by the name of the command to which the options apply. This example defines a <span class="quote">“<span class="quote"><code class="literal">hg vimdiff</code></span>”</span> command that runs the <span class="command"><strong>vim</strong></span> editor's <code class="literal">DirDiff</code> extension.</p><pre class="programlisting">[extdiff] cmd.vimdiff = vimopts.vimdiff = -f '+next' '+execute "DirDiff" argv(0) argv(1)'</pre></div></div><div class="sect1" title="14.3. Cherrypicking changes with the transplant extension"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="sec:hgext:transplant"></a>14.3. Cherrypicking changes with the <code class="literal">transplant</code> extension</h2></div></div></div><p id="x_530"></a>Need to have a long chat with Brendan about this.</p></div><div class="sect1" title="14.4. Send changes via email with the patchbomb extension"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="sec:hgext:patchbomb"></a>14.4. Send changes via email with the <code class="literal">patchbomb</code> extension</h2></div></div></div><p id="x_531"></a>Many projects have a culture of <span class="quote">“<span class="quote">change review</span>”</span>, in which people send their modifications to a mailing list for others to read and comment on before they commit the final version to a shared repository. Some projects have people who act as gatekeepers; they apply changes from other people to a repository to which those others don't have access.</p><p id="x_532"></a>Mercurial makes it easy to send changes over email for review or application, via its <code class="literal">patchbomb</code> extension. The extension is so named because changes are formatted as patches, and it's usual to send one changeset per email message. Sending a long series of changes by email is thus much like <span class="quote">“<span class="quote">bombing</span>”</span> the recipient's inbox, hence <span class="quote">“<span class="quote">patchbomb</span>”</span>.</p><p id="x_533"></a>As usual, the basic configuration of the <code class="literal">patchbomb</code> extension takes just one or two lines in your <code class="filename"> /.hgrc</code>.</p><pre class="programlisting">[extensions]patchbomb =</pre><p id="x_534"></a>Once you've enabled the extension, you will have a new command available, named <span class="command"><strong>email</strong></span>.</p><p id="x_535"></a>The safest and best way to invoke the <span class="command"><strong>email</strong></span> command is to <span class="emphasis"><em>always</em></span> run it first with the <code class="option">hg -n</code> option. This will show you what the command <span class="emphasis"><em>would</em></span> send, without actually sending anything. Once you've had a quick glance over the changes and verified that you are sending the right ones, you can rerun the same command, with the <code class="option">hg -n</code> option removed.</p><p id="x_536"></a>The <span class="command"><strong>email</strong></span> command accepts the same kind of revision syntax as every other Mercurial command. For example, this command will send every revision between 7 and <code class="literal">tip</code>, inclusive.</p><pre class="programlisting">hg email -n 7:tip</pre><p id="x_537"></a>You can also specify a <span class="emphasis"><em>repository</em></span> to compare with. If you provide a repository but no revisions, the <span class="command"><strong>email</strong></span> command will send all revisions in the local repository that are not present in the remote repository. If you additionally specify revisions or a branch name (the latter using the <code class="option">hg -b</code> option), this will constrain the revisions sent.</p><p id="x_538"></a>It's perfectly safe to run the <span class="command"><strong>email</strong></span> command without the names of the people you want to send to: if you do this, it will just prompt you for those values interactively. (If you're using a Linux or Unix-like system, you should have enhanced <code class="literal">readline</code>-style editing capabilities when entering those headers, too, which is useful.)</p><p id="x_539"></a>When you are sending just one revision, the <span class="command"><strong>email</strong></span> command will by default use the first line of the changeset description as the subject of the single email message it sends.</p><p id="x_53a"></a>If you send multiple revisions, the <span class="command"><strong>email</strong></span> command will usually send one message per changeset. It will preface the series with an introductory message, in which you should describe the purpose of the series of changes you're sending.</p><div class="sect2" title="14.4.1. Changing the behavior of patchbombs"><div class="titlepage"><div><div><h3 class="title"><a name="id3072184"></a>14.4.1. Changing the behavior of patchbombs</h3></div></div></div><p id="x_53b"></a>Not every project has exactly the same conventions for sending changes in email; the <code class="literal">patchbomb</code> extension tries to accommodate a number of variations through command line options.</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p id="x_53c"></a>You can write a subject for the introductory message on the command line using the <code class="option">hg -s</code> option. This takes one argument, the text of the subject to use.</p></li><li class="listitem"><p id="x_53d"></a>To change the email address from which the messages originate, use the <code class="option">hg -f</code> option. This takes one argument, the email address to use.</p></li><li class="listitem"><p id="x_53e"></a>The default behavior is to send unified diffs (see <a class="xref" href="managing-change-with-mercurial-queues.html#sec:mq:patch" title="12.4. Understanding patches">Section 12.4, “Understanding patches”</a> for a description of the format), one per message. You can send a binary bundle instead with the <code class="option">hg -b</code> option.</p></li><li class="listitem"><p id="x_53f"></a>Unified diffs are normally prefaced with a metadata header. You can omit this, and send unadorned diffs, with the <code class="option">hg --plain</code> option.</p></li><li class="listitem"><p id="x_540"></a>Diffs are normally sent <span class="quote">“<span class="quote">inline</span>”</span>, in the same body part as the description of a patch. This makes it easiest for the largest number of readers to quote and respond to parts of a diff, as some mail clients will only quote the first MIME body part in a message. If you'd prefer to send the description and the diff in separate body parts, use the <code class="option">hg -a</code> option.</p></li><li class="listitem"><p id="x_541"></a>Instead of sending mail messages, you can write them to an <code class="literal">mbox</code>-format mail folder using the <code class="option">hg -m</code> option. That option takes one argument, the name of the file to write to.</p></li><li class="listitem"><p id="x_542"></a>If you would like to add a <span class="command"><strong>diffstat</strong></span>-format summary to each patch, and one to the introductory message, use the <code class="option">hg -d</code> option. The <span class="command"><strong>diffstat</strong></span> command displays a table containing the name of each file patched, the number of lines affected, and a histogram showing how much each file is modified. This gives readers a qualitative glance at how complex a patch is.</p></li></ul></div></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="advanced-uses-of-mercurial-queues.html">Prev</a> </td><td width="20%" align="center"> </td><td width="40%" align="right"> <a accesskey="n" href="migrating-to-mercurial.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 13. Advanced uses of Mercurial Queues </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Appendix A. Migrating to Mercurial</td></tr></table></div></body></html>