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<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>
