Fossil

<title>Deleting Content From Fossil</title>

<h2>Good Reasons for Removing Content from a Fossil Repository</h2>

Fossil is designed to keep all historical content forever. Fossil

purposely makes it difficult for users to delete content.  Old content
is part of the project's <i>*ahem*</i> fossil record and should be
maintained indefinitely to maintain an accurate history of the project.


Nevertheless, there may occasionally arise legitimate reasons for
deleting content.  Such reasons include:

  *  Spammers inserted inappropriate content into a wiki page, forum post,
     or ticket. Fossil lets you easily hide or amend such content, but
     since it is not a legitimate part of the project's history, there
     is no value in keeping it, so it is best removed permanently.

  *  A file that contains trade secrets or that is under someone else's
     copyright was accidentally committed and needs to be backed out.


  *  A malformed control artifact was inserted and is disrupting the
     operation of Fossil.


<h2>Alternatives</h2>

All of these are rare cases: Fossil is [./antibot.wiki | designed to
foil spammers up front], legally problematic check-ins should range from
rare to nonexistent, and you have to go way out of your way to force
Fossil to insert bad control artifacts. Therefore, before we get to
methods of permanently deleting content from a Fossil repos, let's give
some alternatives that usually suffice, which don't damage the project's
fossil record:

<ul>
    <li><p>When a forum post or wiki article is "deleted," what actually
    happens is that a new empty version is added to the Fossil
    [./blockchain.md | block chain]. The web interface interprets this
    as "deleted," but the prior version remains available if you go
    digging for it.</p></li>

    <li><p>When you close a ticket, it's marked in a way that causes it
    to not show up in the normal ticket reports. You usually want to
    give it a Resolution such as "Rejected" when this happens, plus
    possibly a comment explaining why you're closing it. This is all new
    information added to the ticket, not deletion.</p></li>

    <li><p>When you <tt>fossil rm</tt> a file, a new manifest is
    checked into the repository with the same file list as for the prior
    version minus the "removed" file. The file is still present in the
    repository; it just isn't part of that version forward on that
    branch.</p></li>

    <li><p>If you make a bad check-in, you can shunt it off to the side
    by amending it to put it on a different branch, then continuing
    development on the prior branch:
    <p>
    <tt>$ fossil amend abcd1234 --branch BOGUS --hide<br>
    $ fossil up trunk</tt>
    <p>
    The first command moves check-in ID <tt>abcd1234</tt> (and any
    subsequent check-ins on that branch!) to a branch called
    <tt>BOGUS</tt>, then hides it so it doesn't show up on the
    timeline. You can call this branch anything you like, and you can
    re-use the same name as many times as you like. No content is
    actually deleted: it's just shunted off to the side and hidden away.
    You might find it easier to do this from the Fossil web UI in
    the "edit" function for a check-in.
    <p>
    The second command returns to the last good check-in on that branch
    so you can continue work from that point.</p></li>

    <li><p>When the check-in you want to remove is followed by good
    check-ins on the same branch, you can't use the previous method,
    because it will move the good check-ins, too. The solution is:
    <p>
    <tt>$ fossil merge --backout abcd1234</tt>
    <p>That creates a diff in the check-out directory that backs out the
    bad check-in <tt>abcd1234</tt>. You then fix up any merge conflicts,
    build, test, etc., then check the reverting change into the
    repository. Again, nothing is actually deleted; you're just adding
    more information to the repository which corrects a prior
    check-in.</p></li>
</ul>


<h2>Shunning</h2>

Fossil provides a mechanism called "shunning" for removing content from
a repository.

Every Fossil repository maintains a list of the hash names of