1.\"
  2.\" Copyright (c) 2019 Ted Unangst
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 16.Dd $Mdocdate$
 17.Dt HFCS 1
 18.Os
 19.Sh NAME
 20.Nm hfcs
 21.Nd honk filtering and censorship system
 22.Sh DESCRIPTION
 23The honk filtering and censorship system,
 24.Nm hfcs ,
 25controls what messages are seen and how they are presented to the user.
 26Filter rules are based on a series of matches and actions.
 27It is accessed via the
 28.Pa filters
 29menu item.
 30.Pp
 31Each filter has an optional
 32.Ar name
 33and
 34.Ar notes
 35for user defined purposes.
 36.Pp
 37The following match types are possible.
 38All nonempty criteria must match.
 39.Bl -tag -width include-audience
 40.It Ar who
 41Match an actor or domain name.
 42Matches against
 43.Fa Ar actor
 44property.
 45.It Ar include audience
 46Previous match is applied against
 47.Fa to
 48and
 49.Fa cc
 50fields as well.
 51.It Ar text
 52Regular expression match against the post
 53.Fa content .
 54The special value of "." will match any post with a summary only.
 55.It Ar is reply
 56A reply to another post.
 57.It Ar is announce
 58Is announced (shared).
 59.It Ar announce of
 60Limit prevous match to only specified actor or domain name.
 61.El
 62.Pp
 63The following actions may be applied.
 64Multiple actions may be applied, but some are subsumed by others.
 65.Bl -tag -width tenletters
 66.It Ar reject
 67Reject this message entirely.
 68.It Ar skip media
 69Don't include images or attachments.
 70.It Ar hide
 71Remove this message from most feeds.
 72.It Ar collapse
 73Show only a short summary with click to view content.
 74.It Ar rewrite
 75Rewrite message content, using
 76.Ar replace
 77replacement text.
 78.El
 79.Pp
 80The
 81.Ar text
 82and
 83.Ar rewrite
 84fields are case insensitive word anchored regular expressions.
 85Specifically, an argument
 86.Ql re
 87will be automatically rewritten as
 88.Ql \\\b(?i:re)\\\b .
 89The
 90.Ar replace
 91text may refer to submatches using $1, etc.
 92.Pp
 93A post marked sensitive that does not otherwise contain a summary will
 94have an invisible summary of
 95.Dq unspecified horror
 96that can be matched against and will appear if the post is collapsed.
 97.Pp
 98An optional expiration may be specified as a duration.
 99XdYhZm for X days, Y hours, and Z minutes.
100.Sh SEE ALSO
101.Xr honk 1
102.Sh CAVEATS
103Not seeing is not erasing.