SVN Reverting and Undo — What to Do When Something Goes Wrong

1. Telling the several kinds of “revert” apart

When you use SVN, “reverting” can mean different things:

These three scenarios are handled in completely different ways; each is explained below.

2. Undoing a local, uncommitted change

Undoing a single file

svn revert src/main.cpp

The file goes back to the state it had at the last svn update or svn commit. Note: this cannot be undone.

Undoing a whole directory

svn revert -R .

Recursively undoes the changes to every file under the current directory.

Undoing a new file that was added but not committed

svn revert new-file.txt

For a file that was svn add-ed but not committed, svn revert cancels the addition.

Checking what is about to be reverted

It is best to confirm before you revert:

svn diff src/main.cpp
svn status

3. Undoing a change that has already been committed (reverse merge)

A change that has already been committed to the repository cannot be deleted directly; it is undone by means of a “reverse merge”.

Finding the revision number you want to undo

svn log -l 10

Suppose you want to undo the change in revision r1234:

svn merge -c -1234 .

-c -1234 means applying the change from revision 1234 in reverse. This operation produces a “reverse change” in your local working copy.

Confirming and committing

svn diff     # Check that the reversal is correct
svn commit -m "Undo the change in r1234, which introduced a login bug"

Undoing several revisions

To undo the three consecutive revisions r1234, r1235 and r1236:

svn merge -r 1236:1233 .

The meaning is: apply the changes between revision 1236 and 1233 in reverse (from a higher revision to a lower one = reverse).

4. Rolling the whole repository back to a historical revision

If all the changes from some period are problematic and the repository needs to go back to an earlier state:

# Suppose you want to return to the state at r1000
svn merge -r HEAD:1000 .
svn commit -m "Roll the repository back to revision r1000"

This operation applies all the changes made after r1000 in reverse.

5. Undoing a merge

Undoing a merge that has not been committed

svn revert -R .

Undoing a merge that has been committed

# Look at the merge's commit log
svn log --stop-on-copy

# Suppose the merge commit is r2000
svn merge -c -2000 .
svn commit -m "Undo the merge in r2000"

Seeing which revisions have already been merged

svn mergeinfo ^/branches/feature-a --show-revs merged

6. Practical tips

Using the TortoiseSVN graphical interface

TortoiseSVN’s “Show Log” dialog offers an intuitive way to revert revisions:

• Right-click the revision you want to undo → “Revert changes from this revision”
• You can select several revisions at once and revert them in bulk

Making a backup before you revert

# Create a patch of the current state
svn diff > backup.patch

# Or create a branch directly as a backup
svn copy ^/trunk ^/branches/backup-before-revert -m "Backup before reverting"

Seeing what a particular commit changed

svn diff -c r1234

Before doing a reverse merge, first see clearly which files that commit actually changed.

7. Handling common mistakes

Reverting local changes by mistake

If you use svn revert and accidentally undo changes you had not backed up, then unfortunately a local revert in SVN cannot be recovered. This shows once again:

• Check more before committing: svn diff and svn status
• Commit frequently: do not pile up too many changes

Still have changes after a revert?

svn revert only undoes changes to file contents; it does not delete new files that are not under version control. These files show up in svn status as ?, and they must be deleted by hand or added to .svnignore.

# List files that are not under version control
svn status | grep "^?"

# Clean them up by hand
rm unversioned-file.txt

8. Quick reference

Remember the core principle: a committed change cannot be deleted, only reverse-merged. This is an important difference between SVN and Git.

One small step forward every day is a new height!