Subversion has numerous features, switches, bells and whistles, but on a day-to-day basis, odds are that you will only use a few of them. In this section we'll run through the most common things that you might find yourself doing with Subversion in the course of a day's work.
The typical work cycle looks like this:
Update your working copy
svn update
Make changes
svn add
svn delete
svn copy
svn move
Examine your changes
svn status
svn diff
Possibly undo some changes
svn revert
Resolve Conflicts (Merge Others' Changes)
svn update
svn resolved
Commit your changes
svn commit
When working on a project with a team, you'll want to update your working copy to receive any changes made since your last update by other developers on the project. Use svn update to bring your working copy into sync with the latest revision in the repository.
$ svn update U foo.c U bar.c Updated to revision 2.
In this case, someone else checked in modifications to
both foo.c and bar.c
since the last time you updated, and Subversion has updated
your working copy to include those changes.
When the server sends changes to your working copy via svn update, a letter code is displayed next to each item to let you know what actions Subversion performed to bring your working copy up-to-date. To find out what these letters mean, see svn update
Now you can get to work and make changes in your working copy. It's usually most convenient to decide on a discrete change (or set of changes) to make, such as writing a new feature, fixing a bug, etc. The Subversion commands that you will use here are svn add, svn delete, svn copy, svn move, and svn mkdir. However, if you are merely editing files that are already in Subversion, you may not need to use any of these commands until you commit.
There are two kinds of changes you can make to your working copy: file changes and tree changes. You don't need to tell Subversion that you intend to change a file; just make your changes using your text editor, word processor, graphics program, or whatever tool you would normally use. Subversion automatically detects which files have been changed, and in addition handles binary files just as easily as it handles text files—and just as efficiently too. For tree changes, you can ask Subversion to “mark” files and directories for scheduled removal, addition, copying, or moving. While these changes may take place immediately in your working copy, no additions or removals will happen in the repository until you commit them.
Here is an overview of the five Subversion subcommands that you'll use most often to make tree changes.
Schedule file, directory, or symbolic link
foo to be added to the repository.
When you next commit, foo will
become a child of its parent directory. Note that if
foo is a directory, everything
underneath foo will be scheduled
for addition. If you only want to add
foo itself, pass the
--non-recursive (-N) option.
Schedule file, directory, or symbolic link
foo to be deleted from the
repository. If foo is a file or
link, it is immediately deleted from your working copy.
If foo is a directory, it is not
deleted, but Subversion schedules it for deletion. When
you commit your changes, foo will
be removed from your working copy and the repository.
[4]
Create a new item bar as a
duplicate of foo and automatically
schedule bar for addition.
When bar is added to the
repository on the next commit, its copy history is
recorded (as having originally come from
foo). svn copy
does not create intermediate directories.
This command is exactly the same as running
svn copy foo bar; svn delete foo.
That is, bar is scheduled for
addition as a copy of foo, and
foo is scheduled for removal.
svn move does not create intermediate
directories.
This command is exactly the same as running
mkdir blort; svn add blort. That is,
a new directory named blort is
created and scheduled for addition.
Once you've finished making changes, you need to commit them to the repository, but before you do so, it's usually a good idea to take a look at exactly what you've changed. By examining your changes before you commit, you can make a more accurate log message. You may also discover that you've inadvertently changed a file, and this gives you a chance to revert those changes before committing. Additionally, this is a good opportunity to review and scrutinize changes before publishing them. You can see an overview of the changes you've made by using svn status, and dig into the details of those changes by using svn diff.
Subversion has been optimized to help you with this task,
and is able to do many things without communicating with the
repository. In particular, your working copy contains a
secret cached “pristine” copy of each version
controlled file within the .svn area.
Because of this, Subversion can quickly show you how your
working files have changed, or even allow you to undo your
changes without contacting the repository.
To get an overview of your changes, you'll use the svn status command. You'll probably use svn status more than any other Subversion command.
If you run svn status at the top of
your working copy with no arguments, it will detect all file
and tree changes you've made. Below are a few examples of
the most common status codes that svn
status can return. (Note that the text following
# is not
actually printed by svn status.)
A stuff/loot/bloo.h # file is scheduled for addition C stuff/loot/lump.c # file has textual conflicts from an update D stuff/fish.c # file is scheduled for deletion M bar.c # the content in bar.c has local modifications
In this output format svn status prints six columns of characters, followed by several whitespace characters, followed by a file or directory name. The first column tells the status of a file or directory and/or its contents. The codes we listed are:
A itemThe file, directory, or symbolic link
item has been scheduled for
addition into the repository.
C itemThe file item is in a state
of conflict. That is, changes received from the
server during an update overlap with local changes
that you have in your working copy. You must resolve
this conflict before committing your changes to the
repository.
D itemThe file, directory, or symbolic link
item has been scheduled for
deletion from the repository.
M itemThe contents of the file item
have been modified.
If you pass a specific path to svn status, you get information about that item alone:
$ svn status stuff/fish.c D stuff/fish.c
svn status also has a
--verbose (-v) switch, which will show you
the status of every item in your
working copy, even if it has not been changed:
$ svn status -v
M 44 23 sally README
44 30 sally INSTALL
M 44 20 harry bar.c
44 18 ira stuff
44 35 harry stuff/trout.c
D 44 19 ira stuff/fish.c
44 21 sally stuff/things
A 0 ? ? stuff/things/bloo.h
44 36 harry stuff/things/gloo.c
This is the “long form” output of svn status. The first column remains the same, but the second column shows the working-revision of the item. The third and fourth columns show the revision in which the item last changed, and who changed it (these columns are not to be confused with the columns of characters that we just discussed).
None of the above invocations to svn
status contact the repository, they work only
locally by comparing the metadata in the
.svn directory with the working copy.
Finally, there is the --show-updates (-u)
option, which contacts the repository and adds information
about things that are out-of-date:
$ svn status -u -v
M * 44 23 sally README
M 44 20 harry bar.c
* 44 35 harry stuff/trout.c
D 44 19 ira stuff/fish.c
A 0 ? ? stuff/things/bloo.h
Status against revision: 46
Notice the two asterisks: if you were to run
svn update at this point, you would
receive changes to README
and trout.c. This tells you some very
useful information—you'll need to update and get the
server changes on README before you
commit, or the repository will reject your commit for being
out-of-date. (More on this subject later.)
svn status displays much more information about the files and directories in your working copy than we've shown here—for an exhaustive description of svn status and its output, see svn status.
Another way to examine your changes is with the svn diff command. You can find out exactly how you've modified things by running svn diff with no arguments, which prints out file changes in unified diff format:
$ svn diff
Index: bar.c
===================================================================
--- bar.c (revision 3)
+++ bar.c (working copy)
@@ -1,7 +1,12 @@
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <stdio.h>
int main(void) {
- printf("Sixty-four slices of American Cheese...\n");
+ printf("Sixty-five slices of American Cheese...\n");
return 0;
}
Index: README
===================================================================
--- README (revision 3)
+++ README (working copy)
@@ -193,3 +193,4 @@
+Note to self: pick up laundry.
Index: stuff/fish.c
===================================================================
--- stuff/fish.c (revision 1)
+++ stuff/fish.c (working copy)
-Welcome to the file known as 'fish'.
-Information on fish will be here soon.
Index: stuff/things/bloo.h
===================================================================
--- stuff/things/bloo.h (revision 8)
+++ stuff/things/bloo.h (working copy)
+Here is a new file to describe
+things about bloo.
The svn diff command produces this
output by comparing your working files against the cached
“pristine” copies within the
.svn area. Files scheduled for
addition are displayed as all added-text, and files
scheduled for deletion are displayed as all deleted
text.
Output is displayed in unified diff
format. That is, removed lines are prefaced
with a - and added lines are prefaced
with a +. svn diff
also prints filename and offset information useful to the
patch program, so you can generate
“patches” by redirecting the diff output to a
file:
$ svn diff > patchfile
You could, for example, email the patch file to another developer for review or testing prior to commit.
Subversion uses its internal diff engine, which produces
unified diff format, by default. If you want diff output in
a different format, specify an external diff program using
--diff-cmd and pass any flags you'd like to
it using the --extensions (-x) switch. For
example, to see local differences in file
foo.c in context output format while
ignoring case differences, you might run svn diff
--diff-cmd /usr/bin/diff --extensions '-i'
foo.c.
Suppose while viewing the output of svn diff you determine that all the changes you made to a particular file are mistakes. Maybe you shouldn't have changed the file at all, or perhaps it would be easier to make different changes starting from scratch.
This is a perfect opportunity to use svn revert:
$ svn revert README Reverted 'README'
Subversion reverts the file to its pre-modified state by
overwriting it with the cached “pristine” copy
from the .svn area. But also note that
svn revert can undo
any scheduled operations—for
example, you might decide that you don't want to add a new
file after all:
$ svn status foo ? foo $ svn add foo A foo $ svn revert foo Reverted 'foo' $ svn status foo ? foo
svn revert
ITEM has exactly the same
effect as deleting ITEM from
your working copy and then running svn update -r
BASE ITEM. However,
if you're reverting a file, svn revert
has one very noticeable difference—it doesn't have
to communicate with the repository to restore your
file.
Or perhaps you mistakenly removed a file from version control:
$ svn status README
README
$ svn delete README
D README
$ svn revert README
Reverted 'README'
$ svn status README
README
We've already seen how svn status -u can predict conflicts. Suppose you run svn update and some interesting things occur:
$ svn update U INSTALL G README C bar.c Updated to revision 46.
The U and
G codes are no cause for
concern; those files cleanly absorbed changes from the
repository. The files marked with
U contained no local changes
but were Updated with changes
from the repository. The G
stands for merGed, which
means that the file had local changes to begin with, but the
changes coming from the repository didn't overlap with the local
changes.
But the C stands for
conflict. This means that the changes from the server overlapped
with your own, and now you have to manually choose between
them.
Whenever a conflict occurs, three things typically occur to assist you in noticing and resolving that conflict:
Subversion prints a C
during the update, and remembers that the file is in a
state of conflict.
If Subversion considers the file to be mergeable,
it places conflict
markers—special strings of text which
delimit the “sides” of the
conflict—into the file to visibly demonstrate the
overlapping areas. (Subversion uses the
svn:mime-type property to decide if a
file is capable of contextual, line-based merging. See
the section called “File Content Type” to learn more.)
For every conflicted file, Subversion places three extra unversioned files in your working copy:
filename.mineThis is your file as it existed in your working
copy before you updated your working copy—that
is, without conflict markers. This file has only
your latest changes in it. (If Subversion considers
the file to be unmergeable, then the
.mine file isn't created, since
it would be identical to the working file.)
filename.rOLDREVThis is the file that was the
BASE revision before you updated
your working copy. That is, the file that you
checked out before you made your latest
edits.
filename.rNEWREVThis is the file that your Subversion client
just received from the server when you updated your
working copy. This file corresponds to the
HEAD revision of the
repository.
Here OLDREV is the revision number
of the file in your .svn directory
and NEWREV is the revision number of
the repository HEAD.
For example, Sally makes changes to the file
sandwich.txt in the repository. Harry has
just changed the file in his working copy and checked it in.
Sally updates her working copy before checking in and she gets
a conflict:
$ svn update C sandwich.txt Updated to revision 2. $ ls -1 sandwich.txt sandwich.txt.mine sandwich.txt.r1 sandwich.txt.r2
At this point, Subversion will not
allow you to commit the file sandwich.txt
until the three temporary files are removed.
$ svn commit -m "Add a few more things" svn: Commit failed (details follow): svn: Aborting commit: '/home/sally/svn-work/sandwich.txt' remains in conflict
If you get a conflict, you need to do one of three things:
Merge the conflicted text “by hand” (by examining and editing the conflict markers within the file).
Copy one of the temporary files on top of your working file.
Run svn revert <filename> to throw away all of your local changes.
Once you've resolved the conflict, you need to let Subversion know by running svn resolved. This removes the three temporary files and Subversion no longer considers the file to be in a state of conflict.[6]
$ svn resolved sandwich.txt Resolved conflicted state of 'sandwich.txt'
Merging conflicts by hand can be quite intimidating the first time you attempt it, but with a little practice, it can become as easy as falling off a bike.
Here's an example. Due to a miscommunication, you and
Sally, your collaborator, both edit the file
sandwich.txt at the same time. Sally
commits her changes, and when you go to update your working
copy, you get a conflict and you're going to have to edit
sandwich.txt to resolve the conflicts.
First, let's take a look at the file:
$ cat sandwich.txt Top piece of bread Mayonnaise Lettuce Tomato Provolone <<<<<<< .mine Salami Mortadella Prosciutto ======= Sauerkraut Grilled Chicken >>>>>>> .r2 Creole Mustard Bottom piece of bread
The strings of less-than signs, equal signs, and greater-than signs are conflict markers, and are not part of the actual data in conflict. You generally want to ensure that those are removed from the file before your next commit. The text between the first two sets of markers is composed of the changes you made in the conflicting area:
<<<<<<< .mine Salami Mortadella Prosciutto =======
The text between the second and third sets of conflict markers is the text from Sally's commit:
======= Sauerkraut Grilled Chicken >>>>>>> .r2
Usually you won't want to just delete the conflict markers and Sally's changes—she's going to be awfully surprised when the sandwich arrives and it's not what she wanted. So this is where you pick up the phone or walk across the office and explain to Sally that you can't get sauerkraut from an Italian deli.[7] Once you've agreed on the changes you will check in, edit your file and remove the conflict markers.
Top piece of bread Mayonnaise Lettuce Tomato Provolone Salami Mortadella Prosciutto Creole Mustard Bottom piece of bread
Now run svn resolved, and you're ready to commit your changes:
$ svn resolved sandwich.txt $ svn commit -m "Go ahead and use my sandwich, discarding Sally's edits."
Note that svn resolved, unlike most of the other commands we deal with in this chapter, requires an argument. In any case, you want to be careful and only run svn resolved when you're certain that you've fixed the conflict in your file—once the temporary files are removed, Subversion will let you commit the file even if it still contains conflict markers.
If you ever get confused while editing the conflicted file, you can always consult the three files that Subversion creates for you in your working copy—including your file as it was before you updated. You can even use a third-party interactive merging tool to examine those three files.
If you get a conflict and decide that you want to throw out your changes, you can merely copy one of the temporary files created by Subversion over the file in your working copy:
$ svn update C sandwich.txt Updated to revision 2. $ ls sandwich.* sandwich.txt sandwich.txt.mine sandwich.txt.r2 sandwich.txt.r1 $ cp sandwich.txt.r2 sandwich.txt $ svn resolved sandwich.txt
If you get a conflict, and upon examination decide that you want to throw out your changes and start your edits again, just revert your changes:
$ svn revert sandwich.txt Reverted 'sandwich.txt' $ ls sandwich.* sandwich.txt
Note that when you revert a conflicted file, you don't have to run svn resolved.
Finally! Your edits are finished, you've merged all changes from the server, and you're ready to commit your changes to the repository.
The svn commit command sends all of
your changes to the repository. When you commit a change, you
need to supply a log message,
describing your change. Your log message will be attached to
the new revision you create. If your log message is brief,
you may wish to supply it on the command line using the
--message (or -m)
switch:
$ svn commit -m "Corrected number of cheese slices." Sending sandwich.txt Transmitting file data . Committed revision 3.
However, if you've been composing your log message as you
work, you may want to tell Subversion to get the message from
a file by passing the filename with the
--file (-F) option:
$ svn commit -F logmsg Sending sandwich.txt Transmitting file data . Committed revision 4.
If you fail to specify either the
--message or --file switch,
then Subversion will automatically launch your favorite editor
(see the editor-cmd section in
the section called “Config”) for composing a log
message.
If you're in your editor writing a commit message and decide that you want to cancel your commit, you can just quit your editor without saving changes. If you've already saved your commit message, simply delete the text, save again, then quit.
$ svn commit Waiting for Emacs...Done Log message unchanged or not specified a)bort, c)ontinue, e)dit a $
The repository doesn't know or care if your changes make any sense as a whole; it only checks to make sure that nobody else has changed any of the same files that you did when you weren't looking. If somebody has done that, the entire commit will fail with a message informing you that one or more of your files is out-of-date:
$ svn commit -m "Add another rule" Sending rules.txt svn: Commit failed (details follow): svn: Your file or directory 'sandwich.txt' is probably out-of-date …
At this point, you need to run svn update, deal with any merges or conflicts that result, and attempt your commit again.
That covers the basic work cycle for using Subversion. There are many other features in Subversion that you can use to manage your repository and working copy, but most of your day-to-day use of Subversion will involve only the commands that we've discussed so far in this chapter. We will, however, cover a few more commands that you'll use just fairly often.
[4] Of course, nothing is ever totally
deleted from the repository—just from the
HEAD of the repository. You can get
back anything you delete by checking out (or updating
your working copy) a revision earlier than the one in
which you deleted it. Also see the section called “Resurrecting Deleted Items”>
[5] And also that you don't have a WAN card. Thought you got us, huh?
[6] You can always remove the temporary files yourself, but would you really want to do that when Subversion can do it for you? We didn't think so.
[7] And if you ask them for it, they may very well ride you out of town on a rail.