<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Revision Specifiers</title><link rel="stylesheet" href="styles.css" type="text/css" /><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /><link rel="start" href="index.html" title="Version Control with Subversion" /><link rel="up" href="svn.advanced.html" title="Chapter 3. Advanced Topics" /><link rel="prev" href="svn.advanced.html" title="Chapter 3. Advanced Topics" /><link rel="next" href="svn.advanced.props.html" title="Properties" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Revision Specifiers</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="svn.advanced.html">Prev</a> </td><th width="60%" align="center">Chapter 3. Advanced Topics</th><td width="20%" align="right"> <a accesskey="n" href="svn.advanced.props.html">Next</a></td></tr></table><hr /></div><div class="sect1" lang="en" xml:lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="svn.tour.revs.specifiers"></a>Revision Specifiers</h2></div></div></div><p>As you saw in <a class="xref" href="svn.basic.in-action.html#svn.basic.in-action.revs" title="Revisions">the section called “Revisions”</a>, revision numbers in Subversion are pretty straightforward—integers that keep getting larger as you commit more changes to your versioned data. Still, it doesn't take long before you can no longer remember exactly what happened in each and every revision. Fortunately, the typical Subversion workflow doesn't often demand that you supply arbitrary revisions to the Subversion operations you perform. For operations that <span class="emphasis"><em>do</em></span> require a revision specifier, you generally supply a revision number that you saw in a commit email, in the output of some other Subversion operation, or in some other context that would give meaning to that particular number.</p><p>But occasionally, you need to pinpoint a moment in time for which you don't already have a revision number memorized or handy. So besides the integer revision numbers, <span class="command"><strong>svn</strong></span> allows as input some additional forms of revision specifiers—<em class="firstterm">revision keywords</em>, and revision dates.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>The various forms of Subversion revision specifiers can be mixed and matched when used to specify revision ranges. For example, you can use <code class="option">-r <em class="replaceable"><code>REV1</code></em>:<em class="replaceable"><code>REV2</code></em></code> where <em class="replaceable"><code>REV1</code></em> is a revision keyword and <em class="replaceable"><code>REV2</code></em> is a revision number, or where <em class="replaceable"><code>REV1</code></em> is a date and <em class="replaceable"><code>REV2</code></em> is a revision keyword, and so on. The individual revision specifiers are independently evaluated, so you can put whatever you want on the opposite sides of that colon.</p></div><div class="sect2" lang="en" xml:lang="en"><div class="titlepage"><div><div><h3 class="title"><a id="svn.tour.revs.keywords"></a>Revision Keywords</h3></div></div></div><a id="id357812" class="indexterm"></a><a id="id357824" class="indexterm"></a><a id="id357833" class="indexterm"></a><a id="id357842" class="indexterm"></a><a id="id357851" class="indexterm"></a><p>The Subversion client understands a number of revision keywords. These keywords can be used instead of integer arguments to the <code class="option">--revision (-r)</code> switch, and are resolved into specific revision numbers by Subversion:</p><div class="variablelist"><dl><dt><span class="term">HEAD</span></dt><dd><p>The latest (or “<span class="quote">youngest</span>”) revision in the repository.</p></dd><dt><span class="term">BASE</span></dt><dd><p>The revision number of an item in a working copy. If the item has been locally modified, the “<span class="quote">BASE version</span>” refers to the way the item appears without those local modifications.</p></dd><dt><span class="term">COMMITTED</span></dt><dd><p>The most recent revision prior to, or equal to, <code class="literal">BASE</code>, in which an item changed.</p></dd><dt><span class="term">PREV</span></dt><dd><p>The revision immediately <span class="emphasis"><em>before</em></span> the last revision in which an item changed. Technically, this boils down to <code class="literal">COMMITTED</code>-1.</p></dd></dl></div><p>As can be derived from their descriptions, the <code class="literal">PREV</code>, <code class="literal">BASE</code>, and <code class="literal">COMMITTED</code> revision keywords are used only when referring to a working copy path—they don't apply to repository URLs. <code class="literal">HEAD</code>, on the other hand, can be used in conjunction with both of these path types.</p><p>Here are some examples of revision keywords in action:</p><pre class="screen"> $ svn diff -r PREV:COMMITTED foo.c # shows the last change committed to foo.c $ svn log -r HEAD # shows log message for the latest repository commit $ svn diff -r HEAD # compares your working copy (with all of its local changes) to the # latest version of that tree in the repository $ svn diff -r BASE:HEAD foo.c # compares the unmodified version of foo.c with the latest version of # foo.c in the repository $ svn log -r BASE:HEAD # shows all commit logs for the current versioned directory since you # last updated $ svn update -r PREV foo.c # rewinds the last change on foo.c, decreasing foo.c's working revision $ svn diff -r BASE:14 foo.c # compares the unmodified version of foo.c with the way foo.c looked # in revision 14 </pre></div><div class="sect2" lang="en" xml:lang="en"><div class="titlepage"><div><div><h3 class="title"><a id="svn.tour.revs.dates"></a>Revision Dates</h3></div></div></div><a id="id358010" class="indexterm"></a><p>Revision numbers reveal nothing about the world outside the version control system, but sometimes you need to correlate a moment in real time with a moment in version history. To facilitate this, the <code class="option">--revision (-r)</code> option can also accept as input date specifiers wrapped in curly braces (<code class="literal">{</code> and <code class="literal">}</code>). Subversion accepts the standard ISO-8601 date and time formats, plus a few others. Here are some examples. (Remember to use quotes around any date that contains spaces.)</p><pre class="screen"> $ svn checkout -r {2006-02-17} $ svn checkout -r {15:30} $ svn checkout -r {15:30:00.200000} $ svn checkout -r {"2006-02-17 15:30"} $ svn checkout -r {"2006-02-17 15:30 +0230"} $ svn checkout -r {2006-02-17T15:30} $ svn checkout -r {2006-02-17T15:30Z} $ svn checkout -r {2006-02-17T15:30-04:00} $ svn checkout -r {20060217T1530} $ svn checkout -r {20060217T1530Z} $ svn checkout -r {20060217T1530-0500} … </pre><p>When you specify a date, Subversion resolves that date to the most recent revision of the repository as of that date, and then continues to operate against that resolved revision number:</p><pre class="screen"> $ svn log -r {2006-11-28} ------------------------------------------------------------------------ r12 | ira | 2006-11-27 12:31:51 -0600 (Mon, 27 Nov 2006) | 6 lines … </pre><div class="sidebar"><p class="title"><b>Is Subversion a Day Early?</b></p><p>If you specify a single date as a revision without specifying a time of day (for example <code class="literal">2006-11-27</code>), you may think that Subversion should give you the last revision that took place on the 27th of November. Instead, you'll get back a revision from the 26th, or even earlier. Remember that Subversion will find the <span class="emphasis"><em>most recent revision of the repository</em></span> as of the date you give. If you give a date without a timestamp, like <code class="literal">2006-11-27</code>, Subversion assumes a time of 00:00:00, so looking for the most recent revision won't return anything on the day of the 27th.</p><p>If you want to include the 27th in your search, you can either specify the 27th with the time (<code class="literal">{"2006-11-27 23:59"}</code>), or just specify the next day (<code class="literal">{2006-11-28}</code>).</p></div><p>You can also use a range of dates. Subversion will find all revisions between both dates, inclusive:</p><pre class="screen"> $ svn log -r {2006-11-20}:{2006-11-29} … </pre><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>Since the timestamp of a revision is stored as an unversioned, modifiable property of the revision (see <a class="xref" href="svn.advanced.props.html" title="Properties">the section called “Properties”</a>, revision timestamps can be changed to represent complete falsifications of true chronology, or even removed altogether. Subversion's ability to correctly convert revision dates into real revision numbers depends on revision datestamps maintaining a sequential ordering—the younger the revision, the younger its timestamp. If this ordering isn't maintained, you will likely find that trying to use dates to specify revision ranges in your repository doesn't always return the data you might have expected.</p></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="svn.advanced.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="svn.advanced.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="svn.advanced.props.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 3. Advanced Topics </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Properties</td></tr></table></div></body></html>