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 .
 54.It Ar is announce
 55Is announced (shared).
 56.It Ar announce of
 57Limit prevous match to only specified actor or domain name.
 58.El
 59.Pp
 60The following actions may be applied.
 61Multiple actions may be applied, but some are subsumed by others.
 62.Bl -tag -width tenletters
 63.It Ar reject
 64Reject this message entirely.
 65.It Ar skip media
 66Don't include images or attachments.
 67.It Ar hide
 68Remove this message from most feeds.
 69.It Ar collapse
 70Show only a short summary with click to view content.
 71.It Ar rewrite
 72Rewrite message content, using
 73.Ar replace
 74replacement text.
 75.El
 76.Pp
 77The
 78.Ar text
 79and
 80.Ar rewrite
 81fields are case insensitive word anchored regular expressions.
 82Specifically, an argument
 83.Ql re
 84will be automatically rewritten as
 85.Ql \\\b(?i:re)\\\b .
 86The
 87.Ar replace
 88text may refer to submatches using $1, etc.
 89.Pp
 90A post marked sensitive that does not otherwise contain a summary will
 91have an invisible summary of
 92.Dq unspecified horror
 93that can be matched against and will appear if the post is collapsed.
 94.Pp
 95An optional expiration may be specified as a duration.
 96XdYhZm for X days, Y hours, and Z minutes.
 97.Sh SEE ALSO
 98.Xr honk 1
 99.Sh CAVEATS
100Not seeing is not erasing.