Deleting Content From Fossil

<title>Deleting Content From Fossil</title>
<h1 align="center">Deleting Content From Fossil</h1>

Fossil is designed to keep all historical content forever.  Users
of Fossil are discouraged from "deleting" content simply because it
has become obsolete.  Old content is part of the historical record
(part of the "fossil record") and should be maintained indefinitely.  
Such is the design intent of Fossil.

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

  *  Spammers have inserted inappropriate content into a wiki page
     or ticket that needs to be removed.

  *  A file that contains trade secrets or that is under copyright
     may have been accidentally committed and needs to be backed
     out.

  *  A malformed control artifact may have been inserted and is
     disrupting the operation of Fossil.

<h2>Shunning</h2>

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

Every Fossil repository maintains a list of the SHA1 hash names of
"shunned" artifacts.
Fossil will refuse to push or pull any shunned artifact.  
Furthermore, all shunned artifacts (but not the shunning list
itself) are removed from the
repository whenever the repository is reconstructed using the
"rebuild" command.

<h3>Shunning lists are local state</h3>

The shunning list is part of the local state of a Fossil repository.
In other words, shunning does not propagate using the normal "sync"
mechanism.  An artifact can be
shunned from one repository but be allowed to exist in another.  The fact that
the shunning list does not propagate is a security feature.  If the
shunning list propagated then a malicious user (or
a bug in the fossil code) might introduce a shun record that would
propagate through all repositories in a network and permanently 
destroy vital information.  By refusing to propagate the shunning list,
Fossil insures that no remote user will ever be able to remove 
information from your personal repositories without your permission.

The shunning list does not propagate by the normal "sync" mechanism,
but it is still possible to copy shuns from one repository to another
using the "configuration" command:

    <b>fossil configuration pull shun</b> <i>remote-url</i><br>
    <b>fossil configuration push shun</b> <i>remote-url</i>

The two command above will pull or push shunning lists from or to
the <i>remote-url</i> indicated and merge the lists on the receiving
end.  "Admin" privilege on the remote server is required in order to
push a shun list.  

Note that the shunning list remains in the repository even after the
shunned artifact has been removed.  This is to prevent the artifact
from being reintroduced into the repository the next time it syncs with
another repository that has not shunned the artifact.

<h3>Managing the shunning list</h3>

The complete shunning list for a repository can be viewed by a user
with "admin" privilege on the "/shunned" URL of the web interface to Fossil.  
That URL is accessible under the "Admin" button on the default menu
bar.  Items can be added to or removed from the shunning list.  "Sync"
operations are inhibited as soon as the artifact is added to the
shunning list, but the content of the artifact is not actually removed
from the repository until the next time the repository is rebuilt.

When viewing individual artifacts with the web interface, "admin"
users will usually see a "Shun" option in the submenu that will take
them directly to the shunning page and enable that artifact to be
shunned with a single additional mouse click.