.\" Copyright (c) 1983, 1990 Regents of the University of California.
.\" All rights reserved.
.\"
.\" %sccs.include.redist.roff%
.\"
.\"     @(#)lookbib.1	6.5 (Berkeley) 07/29/91
.\"
.Dd 
.Dt LOOKBIB 1
.Os BSD 4.2
.Sh NAME
.Nm indxbib , lookbib
.Nd build inverted index for a bibliography,
find references in a bibliography
.Sh SYNOPSIS
.Nm indxbib
.Ar database ...
.Nm lookbib
.Op Fl n
.Ar database
.Sh DESCRIPTION
.Nm Indxbib
builds an inverted index to the named
.Ar databases
(or files), which can then be
used by
.Nm lookbib
and
.Xr refer  1  .
The files are assumed to be
.Xr refer
style bibliographic databases
(see
.Xr addbib 1 ) .
.Pp
.Nm Indxbib
is a shell script which calls
.Nm mkey
and
.Nm inv .
The first program,
.Nm mkey ,
truncates words to 6 characters,
and maps upper case to lower case.
It also discards words shorter than 3 characters,
words among the 100 most common English words,
and numbers (dates) < 1900 or > 2000.
These parameters can be changed; see page 4 of a
.Em Refer
document by Mike Lesk (See the SEE ALSO section below).
The second program,
.Nm inv ,
creates an entry file
.Pq Ar file Ns .ia ,
a posting file
.Pq Ar file Ns .ib ,
and a tag file
.Pq Ar file Ns .ic ,
all in the working directory.
.Pp
.Nm Lookbib
uses an inverted index made by
.Nm indxbib
to find sets of bibliographic references.
It reads keywords typed after the ``>'' prompt on the terminal,
and retrieves records containing all these keywords.
If nothing matches, nothing is returned except another ``>'' prompt.
.Pp
.Nm Lookbib
will ask if you need instructions, and will print some brief information if
you reply ``y''.  The
.Fl n
flag turns off the prompt for instructions.
.Pp
It is possible to search multiple databases,
as long as they have a common index made by
.Nm indxbib .
In that case, only the first argument given to
.Nm indxbib
is specified to
.Nm lookbib .
.Pp
If
.Nm lookbib
does not find the index files (the
.Ar file Ns .i[abc]
files),
it looks for a reference file with the same name as the argument,
without the suffixes.
It creates a file with a
`.ig' suffix, suitable for use with
.Xr fgrep 1 .
It then uses this fgrep file to find references.
This method is simpler to use, but the
.Ar file Ns ig
is slower to use
than the
.Ar file Ns .i[abc]
files, and does not allow the use of multiple reference files.
.Sh FILES
.Bl -tag -width /usr/libexec/mkey -compact
.It Pa \&*.ia
Entry file.
.It Pa \&*.ib
Posting file.
.It Pa \&*.ic
Tag file.
.It Pa \&*.ig
Ascii file created if index files not found.
.It Pa /usr/libexec/mkey
Make keys program.
.It Pa /usr/libexec/inv
Hash and invert program.
.El
.Sh SEE ALSO
.Xr refer 1 ,
.Xr addbib 1 ,
.Xr sortbib 1 ,
.Xr roffbib 1 ,
.Xr lookbib 1
.Sh BUGS
More than one blank line in between citations
can wreak havoc.
.Pp
Probably all dates should be indexed,
since many disciplines refer to literature
written in the 1800s or earlier.
.Sh HISTORY
A
.Nm lookbib
command appeared in
.At 32v .