.\" $Revision: 1.9 $
.TH PRUNEHISTORY 8
.SH NAME
prunehistory \- remove file names from Usenet history file
.SH SYNOPSIS
.B prunehistory
[
.BI \-f " filename"
]
[
.B \-p
]
[
.I input
]
.SH DESCRIPTION
.I Prunehistory
modifies the
.IR history (5)
text file to ``remove'' a set of filenames from it.
The filenames are removed by overwriting them with spaces, so that the
size and position of any following entries does not change.
.PP
.I Prunehistory
reads the named
.I input
file, or standard input if no file is given.
The input is taken as a set of lines.
Blank lines and lines starting with a number sign (``#'') are ignored.
All other lines are should consist of a Message-ID followed by zero or
more filenames.
.PP
The Messge-ID is used as the
.IR dbz (3)
key to get an offset into the text file.
If no filenames are mentioned on the input line, then all filenames in
the text are ``removed.''
If any filenames are mentioned, they are converted into the history file
notation.
If they appear in the line for the specified Message-ID then they are removed.
.PP
Since
.IR innd (8)
only appends
to the text file,
.I prunehistory
does not need to have any interaction with it.
.SH OPTIONS
.TP
.B \-p
.I Prunehistory
will normally complain about lines that do not follow the correct format.
If the ``\-p'' flag is used, then the program will silently print any
invalid lines on its standard output.
(Blank lines and comment lines are also passed through.)
This can be useful when
.I prunehistory
is used as a filter for other programs such as
.IR reap .
.TP
.B \-f
The default name of the history file is
.\" =()<.IR @<_PATH_HISTORY>@ ;>()=
.IR /var/lib/news/history ;
to specify a different name, use the ``\-f'' flag.
.SH EXAMPLES
.PP
It is a good idea to delete purged entries and rebuild the
.I dbz
database every so often by using a script like the following:
.PP
.RS
.nf
ctlinnd throttle "Rebuilding history database"
.\" =()<cd @<_PATH_NEWSLIB>@>()=
cd /var/lib/news
awk 'NF > 2 {
	printf "%s\et%s\et%s", $1, $2, $3;
	for (i = 4; i <= NF; i++)
		printf " %s", $i;
	print "\en";
}' <history >history.n
if makehistory \-r \-f history.n ; then
    mv history.n history
    mv history.n.pag history.pag
    mv history.n.dir history.dir
else
    echo 'Problem rebuilding history; old file not replaced'
f\&i
ctlinnd go "Rebuilding history database"
.fi
.RE
.PP
Note that this keeps no record of expired articles.
.SH HISTORY
Written by Rich $alz <rsalz@uunet.uu.net> for InterNetNews.
.de R$
This is revision \\$3, dated \\$4.
..
.R$ $Id: prunehistory.8,v 1.9 1996/10/29 23:25:05 brister Exp $
.SH "SEE ALSO"
dbz(3),
history(5),
innd(8).