Basic Work Cycle

Basic Work Cycle
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Subversion has numerous features, options, bells, and whistles, but on a day-to-day basis, odds are that you will use only 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. This involves the use of the svn update command.
Make your changes. The most common changes that you'll make are edits to the contents of your existing files. But sometimes you need to add, remove, copy and move files and directories—the svn add, svn delete, svn copy, and svn move commands handle those sorts of structural changes within the working copy.
Review your changes. The svn status and svn diff commands are critical to reviewing the changes you've made in your working copy.
Fix your mistakes. Nobody's perfect, so as you review your changes, you may spot something that's not quite right. Sometimes the easiest way to fix a mistake is start all over again from scratch. The svn revert command restores a file or directory to its unmodified state.
Resolve any conflicts (merge others' changes). In the time it takes you to make and review your changes, others might have made and published changes, too. You'll want to integrate their changes into your working copy to avoid the potential out-of-dateness scenarios when you attempt to publish your own. Again, the svn update command is the way to do this. If this results in local conflicts, you'll need to resolve those using the svn resolve command.
Publish (commit) your changes. The svn commit command transmits your changes to the repository where, if they are accepted, they create the newest versions of all the things you modified. Now others can see your work, too!

Update Your Working Copy

When working on a project that is being modified via multiple working copies, you'll want to update your working copy to receive any changes committed from other working copies since your last update. These might be changes that other members of your project team have made, or they might simply be changes you've made yourself from a different computer. To protect your data, Subversion won't allow you commit new changes to out-of-date files and directories, so it's best to have the latest versions of all your project's files and directories before making new changes of your own.

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, it appears that someone 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, run svn help update or see svn update (up).

Make Your Changes

Now you can get to work and make changes in your working copy. You can make two kinds of changes 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, it handles binary files just as easily as it handles text files—and just as efficiently, too. Tree changes are different, and involve changes to a directory's structure. Such changes include adding and removing files, renaming files or directories, and copying files or directories to new locations. For tree changes, you use Subversion operations to “schedule” files and directories for removal, addition, copying, or moving. These changes may take place immediately in your working copy, but no additions or removals will happen in the repository until you commit them.

Versioning Symbolic Links

On non-Windows platforms, Subversion is able to version files of the special type symbolic link (or “symlink”). A symlink is a file that acts as a sort of transparent reference to some other object in the filesystem, allowing programs to read and write to those objects indirectly by performing operations on the symlink itself.

When a symlink is committed into a Subversion repository, Subversion remembers that the file was in fact a symlink, as well as the object to which the symlink “points.” When that symlink is checked out to another working copy on a non-Windows system, Subversion reconstructs a real filesystem-level symbolic link from the versioned symlink. But that doesn't in any way limit the usability of working copies on systems such as Windows that do not support symlinks. On such systems, Subversion simply creates a regular text file whose contents are the path to which the original symlink pointed. While that file can't be used as a symlink on a Windows system, it also won't prevent Windows users from performing their other Subversion-related activities.

Here is an overview of the five Subversion subcommands that you'll use most often to make tree changes:

svn add FOO: Use this to schedule the 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 want only to add FOO itself, pass the --depth=empty option.
svn delete FOO: Use this to schedule the 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 entirely removed from your working copy and the repository.^[6]
svn copy FOO BAR: 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 unless you pass the --parents option.
svn move FOO BAR: 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 unless you pass the --parents option.
svn mkdir FOO: This command is exactly the same as running mkdir FOO; svn add FOO. That is, a new directory named FOO is created and scheduled for addition.

Changing the Repository Without a Working Copy

Subversion does offer ways to immediately commit tree changes to the repository without an explicit commit action. In particular, specific uses of svn mkdir, svn copy, svn move, and svn delete can operate directly on repository URLs as well as on working copy paths. Of course, as previously mentioned, svn import always makes direct changes to the repository.

There are pros and cons to performing URL-based operations. One obvious advantage to doing so is speed: sometimes, checking out a working copy that you don't already have solely to perform some seemingly simple action is an overbearing cost. A disadvantage is that you are generally limited to a single, or single type of, operation at a time when operating directly on URLs. Finally, the primary advantage of a working copy is in its utility as a sort of “staging area” for changes. You can make sure that the changes you are about to commit make sense in the larger scope of your project before committing them. And, of course, these staged changes can be as complex or as a simple as they need to be, yet result in but a single new revision when committed.

Review Your Changes

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 compose a more accurate log message (a human-readable description of the committed changes stored alongside those changes in the repository). You may also discover that you've inadvertently changed a file, and that you need to undo that change 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 the svn status command, and you can dig into the details of those changes by using the svn diff command.

Look Ma! No Network!

You can use the commands svn status, svn diff, and svn revert without any network access even if your repository is across the network. This makes it easy to manage and review your changes-in-progress when you are working offline or are otherwise unable to contact your repository over the network.

Subversion does this by keeping private caches of pristine, unmodified versions of each versioned file inside its working copy administrative areas. This allows Subversion to report—and revert—local modifications to those files without network access. This cache (called the text-base) also allows Subversion to send the user's local modifications during a commit to the server as a compressed delta (or “difference”) against the pristine version. Having this cache is a tremendous benefit—even if you have a fast Internet connection, it's generally much faster to send only a file's changes rather than the whole file to the server.

See an overview of your changes

To get an overview of your changes, use the svn status command. You'll probably use svn status more than any other Subversion command.

Tip

Because the cvs status command's output was so noisy, and because cvs update not only performs an update, but also reports the status of your local changes, most CVS users have grown accustomed to using cvs update to report their changes. In Subversion, the update and status reporting facilities are completely separate. See the section called “Distinction Between Status and Update” for more details.

If you run svn status at the top of your working copy with no additional arguments, it will detect and report all file and tree changes you've made.

$ svn status
?       scratch.c
A       stuff/loot
A       stuff/loot/new.c
D       stuff/old.c
M       bar.c
$

In its default output mode, svn status prints seven 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. Some of the most common codes that svn status displays are:

? item: The file, directory, or symbolic link item is not under version control.
A item: The file, directory, or symbolic link item has been scheduled for addition into the repository.
C item: The 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 (and weren't resolved during the update). You must resolve this conflict before committing your changes to the repository.
D item: The file, directory, or symbolic link item has been scheduled for deletion from the repository.
M item: The 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) option, 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 letters in the first column mean the same as before, 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.

None of the prior invocations to svn status contact the repository—they merely report what is known about the working copy items based on the records stored in the working copy administrative area and on the timestamps and contents of modified files. But sometimes it is useful to see which of the items in your working copy have been modified in the repository since the last time you updated your working copy. For this, svn status offers the --show-updates (-u) option, which contacts the repository and adds information about items 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 in the previous example 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—because one of those items is also one that you have locally modified (the file README), you'll need to update and get the servers changes for that file before you commit, or the repository will reject your commit for being out of date. We discuss this in more detail later.

svn status can display 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, run svn help status or see svn status (stat, st).

Examine the details of your local modifications

Another way to examine your changes is with the svn diff command, which displays differences in file content. When you run svn diff at the top of your working copy with no arguments, Subversion will print the changes you've made to human-readable files in your working copy. It displays those changes in unified diff format, a format which describes changes as “hunks” (or “snippets”) of a file's content where each line of text is prefixed with a single-character code: a space, which means the line was unchanged; a minus sign (-), which means the line was removed from the file; or a plus sign (+), which means the line was added to the file. In the context of svn diff, those minus-sign- and plus-sign-prefixed lines show how the lines looked before and after your modifications, respectively.

Here's an example:

$ 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 its pristine text-base. Files scheduled for addition are displayed as files in which every line was added; files scheduled for deletion are displayed as if every line was removed from those files. The output from svn diff is compatible with the patch program. The patch program reads and applies patch files (or “patches”), which are files that describe differences made to one or more files. Because of this, you can share the changes you've made in your working copy with someone else without first committing those changes by creating a patch file from the redirected output of svn diff:

$ svn diff > patchfile
$

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 additional flags that it needs via the --extensions (-x) option. For example, you might want Subversion to defer its difference calculation and display to the GNU diff program, asking that program to print local modifications made to the file foo.c in context diff format (another flavor of difference format) while ignoring changes made only to the case of the letters used in the file's contents:

$ svn diff --diff-cmd /usr/bin/diff -x "-i" foo.c
…
$

Fix Your Mistakes

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. You could edit the file again and unmake all those changes. You could try to find a copy of how the file looked before you changed it, and then copy its contents atop your modified version. You could attempt to apply those changes to the file again in reverse using patch -R. And there are probably other approaches you could take.

Fortunately in Subversion, undoing your work and starting over from scratch doesn't require such acrobatics. Just use the svn revert command:

$ svn status README
M       README
$ svn revert README
Reverted 'README'
$ svn status README
$

In this example, Subversion has reverted the file to its premodified state by overwriting it with the pristine version of the file cached in the text-base area. But note that svn revert can undo any scheduled operation—for example, you might decide that you don't want to add a new file after all:

$ svn status new-file.txt
?       new-file.txt
$ svn add new-file.txt
A         new-file.txt
$ svn revert new-file.txt
Reverted 'new-file.txt'
$ svn status new-file.txt
?       new-file.txt
$

Or perhaps you mistakenly removed a file from version control:

$ svn status README
$ svn delete README
D         README
$ svn revert README
Reverted 'README'
$ svn status README
$

The svn revert command offers salvation for imperfect people. It can save you huge amounts of time and energy that would otherwise be spent manually unmaking changes or, worse, disposing of your working copy and checking out a fresh one just to have a clean slate to work with again.

Resolve Any Conflicts

We've already seen how svn status -u can predict conflicts, but dealing with those conflicts is still something that remains to be done. Conflicts can occur any time you attempt to merge or integrate (in a very general sense) changes from the repository into your working copy. By now you know that svn update creates exactly that sort of scenario—that command's very purpose is to bring your working copy up to date with the repository by merging all the changes made since your last update into your working copy. So how does Subversion report these conflicts to you, and how do you deal with them?

Suppose you run svn update and you see this sort of interesting output:

$ svn update
U    INSTALL
G    README
Conflict discovered in 'bar.c'.
Select: (p) postpone, (df) diff-full, (e) edit,
        (mc) mine-conflict, (tc) theirs-conflict,
        (s) show all options:

The U (which stands for “Updated”) and G (for “merGed”) codes are no cause for concern; those files cleanly absorbed changes from the repository. A file marked with U contains no local changes but was updated with changes from the repository. One marked with G had local changes to begin with, but the changes coming from the repository didn't overlap with those local changes.

It's the next few lines which are interesting. First, Subversion reports to you that in its attempt to merge outstanding server changes into the file bar.c, it has detected that some of those changes clash with local modifications you've made to that file in your working copy but have not yet committed. Perhaps someone has changed the same line of text you also changed. Whatever the reason, Subversion instantly flags this file as being in a state of conflict. It then asks you what you want to do about the problem, allowing you to interactively choose an action to take toward resolving the conflict. The most commonly used options are displayed, but you can see all of the options by typing s:

…
Select: (p) postpone, (df) diff-full, (e) edit,
        (mc) mine-conflict, (tc) theirs-conflict,
        (s) show all options: s

  (e)  edit             - change merged file in an editor
  (df) diff-full        - show all changes made to merged file
  (r)  resolved         - accept merged version of file

  (dc) display-conflict - show all conflicts (ignoring merged version)
  (mc) mine-conflict    - accept my version for all conflicts (same)
  (tc) theirs-conflict  - accept their version for all conflicts (same)

  (mf) mine-full        - accept my version of entire file (even non-conflicts)
  (tf) theirs-full      - accept their version of entire file (same)

  (p)  postpone         - mark the conflict to be resolved later
  (l)  launch           - launch external tool to resolve conflict
  (s)  show all         - show this list

Select: (p) postpone, (df) diff-full, (e) edit,
        (mc) mine-conflict, (tc) theirs-conflict,
        (s) show all options:

Let's briefly review each of these options before we go into detail on what each option means.

(e) edit: Open the file in conflict with your favorite editor, as set in the environment variable EDITOR.
(df) diff-full: Display the differences between the base revision and the conflicted file itself in unified diff format.
(r) resolved: After editing a file, tell svn that you've resolved the conflicts in the file and that it should accept the current contents—basically that you've “resolved” the conflict.
(dc) display-conflict: Display all conflicting regions of the file, ignoring changes which were successfully merged.
(mc) mine-conflict: Discard any newly received changes from the server which conflict with your local changes to the file under review. However, accept and merge all non-conflicting changes received from the server for that file.
(tc) theirs-conflict: Discard any local changes which conflict with incoming changes from the server for the file under review. However, preserve all non-conflicting local changes to that file.
(mf) mine-full: Discard all newly received changes from the server for the file under review, but preserve all your local changes for that file.
(tf) theirs-full: Discard all your local changes to the file under review and use only the newly received changes from the server for that file.
(p) postpone: Leave the file in a conflicted state for you to resolve after your update is complete.
(l) launch: Launch an external program to perform the conflict resolution. This requires a bit of preparation beforehand.
(s) show all: Show the list of all possible commands you can use in interactive conflict resolution.

We'll cover these commands in more detail now, grouping them together by related functionality.

Viewing conflict differences interactively

Before deciding how to attack a conflict interactively, odds are that you'd like to see exactly what is in conflict. Two of the commands available at the interactively conflict resolution prompt can assist you here. The first is the “diff-full” command (df), which displays all the local modifications to the file in question plus any conflict regions:

…
Select: (p) postpone, (df) diff-full, (e) edit,
        (mc) mine-conflict, (tc) theirs-conflict,
        (s) show all options: df
--- .svn/text-base/sandwich.txt.svn-base      Tue Dec 11 21:33:57 2007
+++ .svn/tmp/tempfile.32.tmp     Tue Dec 11 21:34:33 2007
@@ -1 +1,5 @@
-Just buy a sandwich.
+<<<<<<< .mine
+Go pick up a cheesesteak.
+=======
+Bring me a taco!
+>>>>>>> .r32
…

The first line of the diff content shows the previous contents of the working copy (the BASE revision), the next content line is your change, and the last content line is the change that was just received from the server (usually the HEAD revision).

The second command is similar to the first, but the “display-conflict” (dc) command shows only the conflict regions, not all the changes made to the file. Additionally, this command uses a slightly different display format for the conflict regions which allows you to more easily compare the file's contents in those regions as they would appear in each of three states: original and unedited; with your local changes applied and the server's conflicting changes ignored; and with only the server's incoming changes applied and your local, conflicting changes reverted.

After reviewing the information provided by these commands, you're ready to move on to the next action.

Resolving conflict differences interactively

There are several different ways to resolve conflicts interactively—two of which allow you to selectively merge and edit changes, the rest of which allow you to simply pick a version of the file and move along.

If you wish to choose some combination of your local changes, you can use the “edit” command (e) to manually edit the file with conflict markers in a text editor (configured per the instructions in the section called “Using External Editors”). After you've edited the file, if you're satisfied with the changes you've made, you can tell Subversion that the edited file is no longer in conflict by using the “resolve” command (r).

Regardless of what your local Unix snob will likely tell you, editing the file by hand in your favorite text editor is a somewhat low-tech way of remedying conflicts (see the section called “Merging conflicts by hand” for a walkthrough). For this reason, Subversion provides the “launch” resolution command (l) to fire up a fancy graphical merge tool instead (see the section called “External merge”).

If you decide that you don't need to merge any changes, but just want to accept one version of the file or the other, you can either choose your changes (a.k.a. “mine”) by using the “mine-full” command (mf) or choose theirs by using the “theirs-full” command (tf).

Finally, there is also a pair of compromise options available. The “mine-conflict” (mc) and “theirs-conflict” (tc) commands instruct Subversion to select your local changes or the server's incoming changes, respectively, as the “winner” for all conflicts in the file. But, unlike the “mine-full” and “theirs-full” commands, these commands preserve both your local changes and changes received from the server in regions of the file where no conflict was detected.

Postponing conflict resolution

This may sound like an appropriate section for avoiding marital disagreements, but it's actually still about Subversion, so read on. If you're doing an update and encounter a conflict that you're not prepared to review or resolve, you can type p to postpone resolving a conflict on a file-by-file basis when you run svn update. If you know in advance that you don't want to resolve any conflicts interactively, you can pass the --non-interactive option to svn update, and any file in conflict will be marked with a C automatically.

The C (for “Conflicted”) means that the changes from the server overlapped with your own, and now you have to manually choose between them after the update has completed. When you postpone a conflict resolution, svn typically does three things 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 that delimit the “sides” of the conflict—into the file to visibly demonstrate the overlapping areas. (Subversion uses the svn:mime-type property to decide whether 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.mine

This is the file as it existed in your working copy before you began the update process. It contains any local modifications you had made to the file up to that point. (If Subversion considers the file to be unmergeable, the .mine file isn't created, since it would be identical to the working file.)

filename.rOLDREV

This is the file as it existed in the BASE revision—that is, the unmodified revision of the file in your working copy before you began the update process—where OLDREV is that base revision number.

filename.rNEWREV

This is the file that your Subversion client just received from the server via the update of your working copy, where NEWREV corresponds to the revision number to which you were updating (HEAD, unless otherwise requested).

For example, Sally makes changes to the file sandwich.txt, but does not yet commit those changes. Meanwhile, Harry commits changes to that same file. Sally updates her working copy before committing and she gets a conflict, which she postpones:

$ svn update
Conflict discovered in 'sandwich.txt'.
Select: (p) postpone, (df) diff-full, (e) edit,
        (mc) mine-conflict, (tc) theirs-conflict,
        (s) show all options: p
C    sandwich.txt
Updated to revision 2.
Summary of conflicts:
  Text conflicts: 1
$ ls -1
sandwich.txt
sandwich.txt.mine
sandwich.txt.r1
sandwich.txt.r2

At this point, Subversion will not allow Sally 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've postponed a conflict, you need to resolve the conflict before Subversion will allow you to commit your changes. You'll do this with the svn resolve command and one of several arguments to the --accept option.

If you want to choose the version of the file that you last checked out before making your edits, choose the base argument.

If you want to choose the version that contains only your edits, choose the mine-full argument.

If you want to choose the version that your most recent update pulled from the server (and thus discarding your edits entirely), choose the theirs-full argument.

However, if you want to pick and choose from your changes and the changes that your update fetched from the server, merge the conflicted text “by hand” (by examining and editing the conflict markers within the file) and then choose the working argument.

svn resolve removes the three temporary files and accepts the version of the file that you specified with the --accept option, and Subversion no longer considers the file to be in a state of conflict:

$ svn resolve --accept working sandwich.txt
Resolved conflicted state of 'sandwich.txt'

Merging conflicts by hand

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 conflict. 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, equals 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. 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 commit, 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 use svn resolve, and you're ready to commit your changes:

$ svn resolve --accept working sandwich.txt
Resolved conflicted state of 'sandwich.txt'
$ svn commit -m "Go ahead and use my sandwich, discarding Sally's edits."

Note that svn resolve, unlike most of the other commands we deal with in this chapter, requires that you explicitly list any filenames that you wish to resolve. In any case, you want to be careful and use svn resolve only 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.

Discarding your changes in favor of a newly fetched revision

If you get a conflict and decide that you want to throw out your changes, you can run svn resolve --accept theirs-full CONFLICTED-PATH and Subversion will discard your edits and remove the temporary files:

$ svn update
Conflict discovered in 'sandwich.txt'.
Select: (p) postpone, (df) diff-full, (e) edit,
        (mc) mine-conflict, (tc) theirs-conflict,
        (s) show all options: p
C    sandwich.txt
Updated to revision 2.
Summary of conflicts:
  Text conflicts: 1
$ ls sandwich.*
sandwich.txt  sandwich.txt.mine  sandwich.txt.r2  sandwich.txt.r1
$ svn resolve --accept theirs-full sandwich.txt
Resolved conflicted state of 'sandwich.txt'
$

Punting: using svn revert

If you decide that you want to throw out your changes and start your edits again (whether this occurs after a conflict or anytime), 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 use svn resolve.

Commit Your Changes

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 (-m) option:

$ 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 in some other text file as you work, you may want to tell Subversion to get the message from that file by passing its filename as the value of 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 (-m) or --file (-F) option, Subversion will automatically launch your favorite editor (see the information on editor-cmd in the section called “Config”) for composing a log message.

	Tip
	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 all the text, save again, and then abort: $ 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 whether your changes make any sense as a whole; it checks only to make sure 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 are out of date:

$ svn commit -m "Add another rule"
Sending        rules.txt
svn: Commit failed (details follow):
svn: File '/sandwich.txt' is out of date
…

(The exact wording of this error message depends on the network protocol and server you're using, but the idea is the same in all cases.)

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. Subversion offers many other features 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 fairly often.

^[6]Of course, nothing is ever totally deleted from the repository—just from its HEAD revision. You may continue to access the deleted item in previous revisions. Should you desire to resurrect the item so that it is again present in HEAD, see the section called “Resurrecting Deleted Items”.

^[7]And if you ask them for it, they may very well ride you out of town on a rail.

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