<?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>Directory Versions</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.forcvs.html" title="Appendix B. Subversion for CVS Users" /><link rel="prev" href="svn.forcvs.revnums.html" title="Revision Numbers Are Different Now" /><link rel="next" href="svn.forcvs.disconnected.html" title="More Disconnected Operations" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Directory Versions</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="svn.forcvs.revnums.html">Prev</a> </td><th width="60%" align="center">Appendix B. Subversion for CVS Users</th><td width="20%" align="right"> <a accesskey="n" href="svn.forcvs.disconnected.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.forcvs.directories"></a>Directory Versions</h2></div></div></div><p>Subversion tracks tree structures, not just file contents.
It's one of the biggest reasons Subversion was written to
replace CVS.</p><p>Here's what this means to you, as a former CVS user:</p><div class="itemizedlist"><ul type="disc"><li><p>The <span class="command"><strong>svn add</strong></span> and <span class="command"><strong>svn
delete</strong></span> commands work on directories now, just as
they work on files. So do <span class="command"><strong>svn copy</strong></span> and
<span class="command"><strong>svn move</strong></span>. However, these commands do
<span class="emphasis"><em>not</em></span> cause any kind of immediate change
in the repository. Instead, the working items are simply
“<span class="quote">scheduled</span>” for addition or deletion. No
repository changes happen until you run <span class="command"><strong>svn
commit</strong></span>.</p></li><li><p>Directories aren't dumb containers anymore; they have
revision numbers like files. (Or more properly, it's
correct to talk about “<span class="quote">directory
<code class="filename">foo/</code> in revision 5</span>”.)</p></li></ul></div><p>Let's talk more about that last point. Directory versioning
is a hard problem; because we want to allow mixed-revision
working copies, there are some limitations on how far we can
abuse this model.</p><p>From a theoretical point of view, we define “<span class="quote">revision
5 of directory <code class="filename">foo</code></span>” to mean a
specific collection of directory-entries and properties. Now
suppose we start adding and removing files from
<code class="filename">foo</code>, and then commit. It would be a lie
to say that we still have revision 5 of
<code class="filename">foo</code>. However, if we bumped
<code class="filename">foo</code>'s revision number after the commit,
that would be a lie too; there may be other changes to
<code class="filename">foo</code> we haven't yet received, because we
haven't updated yet.</p><p>Subversion deals with this problem by quietly tracking
committed adds and deletes in the <code class="filename">.svn</code>
area. When you eventually run <span class="command"><strong>svn update</strong></span>,
all accounts are settled with the repository, and the
directory's new revision number is set correctly.
<span class="emphasis"><em>Therefore, only after an update is it truly safe to
say that you have a “<span class="quote">perfect</span>” revision of a
directory.</em></span> Most of the time, your working copy will
contain “<span class="quote">imperfect</span>” directory revisions.</p><p>Similarly, a problem arises if you attempt to commit
property changes on a directory. Normally, the commit would
bump the working directory's local revision number. But again,
that would be a lie, because there may be adds or deletes that
the directory doesn't yet have, because no update has happened.
<span class="emphasis"><em>Therefore, you are not allowed to commit
property-changes on a directory unless the directory is
up-to-date.</em></span></p><p>For more discussion about the limitations of directory
versioning, see <a class="xref" href="svn.basic.in-action.html#svn.basic.in-action.mixedrevs" title="Mixed Revision Working Copies">the section called “Mixed Revision Working Copies”</a>.</p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="svn.forcvs.revnums.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="svn.forcvs.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="svn.forcvs.disconnected.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Revision Numbers Are Different Now </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> More Disconnected Operations</td></tr></table></div></body></html>
