Version Control with Subversion

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Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

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Chapter 7: Advanced Topics

svn:keywords

Subversion has the ability to substitute keywords—pieces of useful, dynamic infor-

mation about a versioned file—into the contents of the file itself. Keywords gener-

ally describe information about the last time the file was known to be modified.

Because this information changes each time the file changes, and more importantly,

just after the file changes, it is a hassle for any process except the version control sys-

tem to keep the data completely up-to-date. Left to human authors, the information

would inevitably grow stale.

Assume you have a document in which you would like to display the last date on

which it was modified. You could burden every author of that document to, just before

committing their changes, also tweak the part of the document that describes when it

was last changed. But, sooner or later, someone would forget to do that. Instead, sim-

ply ask Subversion to perform keyword substitution on the

LastChangedDate keyword.

You control where the keyword is inserted into your document by placing a keyword

anchor at the desired location in the file. This anchor is just a string of text formatted as

$KeywordName$.

Subversion defines the list of keywords available for substitution. That list contains

the following five keywords,