SVNBOOK Chap2 Basic Work Cycle Examine Your Changes

Look Ma! No Network!

The commands svn status, svn diff, and svn revert can be used without any network access even if your repository is across the network. This makes it easy to manage your changes-in-progress when you are somewhere without a network connection, such as travelling on an airplane, riding a commuter train or hacking on the beach.[5]

Subversion does this by keeping private caches of pristine versions of each versioned file inside of the .svn 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 net connection, it's much faster to send only a file's changes rather than the whole file to the server.

CVS Users: Hold That Update!

You're probably used to using cvs update to see what changes you've made to your working copy. svn status will give you all the information you need regarding what has changed in your working copy—without accessing the repository or potentially incorporating new changes published by other users.

In Subversion, update does just that—it updates your working copy with any changes committed to the repository since the last time you've updated your working copy. You may have to break the habit of using the update command to see what local modifications you've made.

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

• 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. 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

None of the prior invocations to svn status contact the repository—instead, they compare 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

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.

Output is displayed in unified diff format. That is, removed lines are prefaced with - and added lines are prefaced with +. 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.