As we mentioned earlier, the repository is like a time machine. It keeps a record of every change ever committed, and allows you to explore this history by examining previous versions of files and directories as well as the metadata that accompanies them. With a single Subversion command, you can check out the repository (or restore an existing working copy) exactly as it was at any date or revision number in the past. However, sometimes you just want to peer into the past instead of going into the past.
There are several commands that can provide you with historical data from the repository:
Shows you broad information: log messages with date and author information attached to revisions, and which paths changed in each revision.
Shows you the specific details of how a file changed over time.
This is used to retrieve any file as it existed in a particular revision number and display it on your screen.
Displays the files in a directory for any given revision.
To find information about the history of a file or directory, use the svn log command. svn log will provide you with a record of who made changes to a file or directory, at what revision it changed, the time and date of that revision, and, if it was provided, the log message that accompanied the commit.
$ svn log ------------------------------------------------------------------------ r3 | sally | Mon, 15 Jul 2002 18:03:46 -0500 | 1 line Added include lines and corrected # of cheese slices. ------------------------------------------------------------------------ r2 | harry | Mon, 15 Jul 2002 17:47:57 -0500 | 1 line Added main() methods. ------------------------------------------------------------------------ r1 | sally | Mon, 15 Jul 2002 17:40:08 -0500 | 1 line Initial import ------------------------------------------------------------------------
Note that the log messages are printed in
reverse chronological order by default.
If you wish to see a different range of revisions in a
particular order, or just a single revision, pass the
--revision (-r)
switch:
$ svn log --revision 5:19 # shows logs 5 through 19 in chronological order $ svn log -r 19:5 # shows logs 5 through 19 in reverse order $ svn log -r 8 # shows log for revision 8
You can also examine the log history of a single file or directory. For example:
$ svn log foo.c … $ svn log http://foo.com/svn/trunk/code/foo.c …
These will display log messages only for those revisions in which the working file (or URL) changed.
If you want even more information about a file or
directory, svn log also takes a
--verbose (-v) switch.
Because Subversion allows you to move and copy files and
directories, it is important to be able to track path changes
in the filesystem, so in verbose mode, svn
log will include a list of changed paths in a
revision in its output:
$ svn log -r 8 -v ------------------------------------------------------------------------ r8 | sally | 2002-07-14 08:15:29 -0500 | 1 line Changed paths: M /trunk/code/foo.c M /trunk/code/bar.h A /trunk/code/doc/README Frozzled the sub-space winch. ------------------------------------------------------------------------
svn log also takes a --quiet
(-q) switch, which suppresses the body of the
log message. When combined with --verbose, it
gives just the names of the changed files.
We've already seen svn diff before—it displays file differences in unified diff format; it was used to show the local modifications made to our working copy before committing to the repository.
In fact, it turns out that there are three distinct uses of svn diff:
Examine local changes
Compare your working copy to the repository
Compare repository to repository
As we've seen, invoking svn diff with
no switches will compare your working files to the cached
“pristine” copies in
the .svn area:
$ svn diff Index: rules.txt =================================================================== --- rules.txt (revision 3) +++ rules.txt (working copy) @@ -1,4 +1,5 @@ Be kind to others Freedom = Responsibility Everything in moderation -Chew with your mouth open +Chew with your mouth closed +Listen when others are speaking $
If a single --revision
(-r) number is passed, then your
working copy is compared to the specified revision in the
repository.
$ svn diff --revision 3 rules.txt Index: rules.txt =================================================================== --- rules.txt (revision 3) +++ rules.txt (working copy) @@ -1,4 +1,5 @@ Be kind to others Freedom = Responsibility Everything in moderation -Chew with your mouth open +Chew with your mouth closed +Listen when others are speaking $
If two revision numbers, separated by a colon, are
passed via --revision
(-r), then the two revisions are directly
compared.
$ svn diff --revision 2:3 rules.txt Index: rules.txt =================================================================== --- rules.txt (revision 2) +++ rules.txt (revision 3) @@ -1,4 +1,4 @@ Be kind to others -Freedom = Chocolate Ice Cream +Freedom = Responsibility Everything in moderation Chew with your mouth open $
Not only can you use svn diff to compare files in your working copy to the repository, but if you supply a URL argument, you can examine the differences between items in the repository without even having a working copy. This is especially useful if you wish to inspect changes in a file when you don't have a working copy on your local machine:
$ svn diff --revision 4:5 http://svn.red-bean.com/repos/example/trunk/text/rules.txt … $
If you want to examine an earlier version of a file and not necessarily the differences between two files, you can use svn cat:
$ svn cat --revision 2 rules.txt Be kind to others Freedom = Chocolate Ice Cream Everything in moderation Chew with your mouth open $
You can also redirect the output directly into a file:
$ svn cat --revision 2 rules.txt > rules.txt.v2 $
You're probably wondering why we don't just use svn update --revision to update the file to the older revision. There are a few reasons why we might prefer to use svn cat.
First, you may want to see the differences between two revisions of a file using an external diff program (perhaps a graphical one, or perhaps your file is in such a format that the output of unified diff is nonsensical). In this case, you'll need to grab a copy of the old revision, redirect it to a file, and pass both that and the file in your working copy to your external diff program.
Sometimes it's easier to look at an older version of a file in its entirety as opposed to just the differences between it and another revision.
The svn list command shows you what files are in a repository directory without actually downloading the files to your local machine:
$ svn list http://svn.collab.net/repos/svn README branches/ clients/ tags/ trunk/
If you want a more detailed listing, pass the
--verbose (-v) flag to get
output like this:
$ svn list --verbose http://svn.collab.net/repos/svn 2755 harry 1331 Jul 28 02:07 README 2773 sally Jul 29 15:07 branches/ 2769 sally Jul 29 12:07 clients/ 2698 harry Jul 24 18:07 tags/ 2785 sally Jul 29 19:07 trunk/
The columns tell you the revision at which the file or directory was last modified, the user who modified it, the size if it is a file, the date it was last modified, and the item's name.
In addition to all of the above commands, you can use
svn update and svn
checkout with the --revision switch
to take an entire working copy “back in time”
[7]:
$ svn checkout --revision 1729 # Checks out a new working copy at r1729 … $ svn update --revision 1729 # Updates an existing working copy to r1729 …