Table of Contents (3.3.22)

# Undoing mistakes

## Mistakes happen

Breezy has been designed to make it easy to recover from mistakes as explained below.

## Dropping the revision history for a project

If you accidentally put the wrong tree under version control, simply delete the `.brz` directory.

## Deregistering a file or directory

If you accidentally register a file using `add` that you don’t want version controlled, you can use the `remove` command to tell Breezy to forget about it.

`remove` has been designed to Do the Safe Thing in that it will not delete a modified file. For example:

    brz add foo.html
    (oops - didn't mean that)
    brz remove foo.html

This will complain about the file being modified or unknown. If you want to keep the file, use the `--keep` option. Alternatively, if you want to delete the file, use the `--force` option. For example:

    brz add foo.html
    (oops - didn't mean that)
    brz remove --keep foo.html
    (foo.html left on disk, but deregistered)

On the other hand, the unchanged `TODO` file is deregistered and removed from disk without complaint in this example:

    brz add TODO
    brz commit -m "added TODO"
    (hack, hack, hack - but don't change TODO)
    brz remove TODO
    (TODO file deleted)

Note: If you delete a file using your file manager, IDE or via an operating system command, the `commit` command will implicitly treat it as removed.

## Undoing changes since the last commit

One of the reasons for using a version control tool is that it lets you easily checkpoint good tree states while working. If you decide that the changes you have made since the last `commit` ought to be thrown away, the command to use is `revert` like this:

    brz revert

As a precaution, it is good practice to use `brz status` and `brz diff` first to check that everything being thrown away really ought to be.

## Undoing changes to a file since the last commit

If you want to undo changes to a particular file since the last commit but keep all the other changes in the tree, pass the filename as an argument to `revert` like this:

    brz revert foo.py

## Undoing the last commit

If you make a commit and really didn’t mean to, use the `uncommit` command to undo it like this:

    brz uncommit

Unlike `revert`, `uncommit` leaves the content of your working tree exactly as it is. That’s really handy if you make a commit and accidently provide the wrong error message. For example:

    brz commit -m "Fix bug #11"
    (damn - wrong bug number)
    brz uncommit
    brz commit -m "Fix bug #1"

Another common reason for undoing a commit is because you forgot to add one or more files. Some users like to alias `commit` to `commit --strict` so that commits fail if unknown files are found in the tree.

Tags for uncommitted revisions are removed from the branch unless `--keep-tags` was specified.

Note: While the `merge` command is not introduced until the next chapter, it is worth noting now that `uncommit` restores any pending merges. (Running `brz status` after `uncommit` will show these.) `merge` can also be used to effectively undo just a selected commit earlier in history. For more information on `merge`, see Merging changes in the next chapter and the Breezy User Reference.

## Undoing multiple commits

You can use the -r option to undo several commits like this:

    brz uncommit -r -3

If your reason for doing this is that you really want to back out several changes, then be sure to remember that `uncommit` does not change your working tree: you’ll probably need to run the `revert` command as well to complete the task. In many cases though, it’s arguably better to leave your history alone and add a new revision reflecting the content of the last good state.

## Reverting to the state of an earlier version

If you make an unwanted change but it doesn’t make sense to uncommit it (because that code has been released to users say), you can use `revert` to take your working tree back to the desired state. For example:

    % brz commit "Fix bug #5"
    Committed revision 20.
    (release the code)
    (hmm - bad fix)
    brz revert -r 19
    brz commit -m "Backout fix for bug #5"

This will change your entire tree back to the state as of revision 19, which is probably only what you want if you haven’t made any new commits since then. If you have, the `revert` would wipe them out as well. In that case, you probably want to use Reverse cherrypicking instead to back out the bad fix.

Note: As an alternative to using an absolute revision number (like 19), you can specify one relative to the tip (-1) using a negative number like this:

    brz revert -r -2

## Correcting a tag

If you have defined a tag prematurely, use the `--force` option of the `tag` command to redefine it. For example:

    brz tag 2.0-beta-1
    (oops, we're not yet ready for that)
    (make more commits to include more fixes)
    brz tag 2.0-beta-1 --force

## Clearing a tag

If you have defined a tag and no longer want it defined, use the `--delete` option of the `tag` command to remove it. For example:

    brz tag 2.0-beta-4
    (oops, we're not releasing a 4th beta)
    brz tag 2.0-beta-4 --delete