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\" =========================================================================
\" llsearch.1 - The manual page for the llsearch program.
\" Copyright (c) 1997,1998 Fred M. Erickson
\"
\" This program is free software; you can redistribute it and/or modify
\" it under the terms of the GNU General Public License as published by
\" the Free Software Foundation; either version 2, or (at your option)
\" any later version.
\"
\" This program is distributed in the hope that it will be useful,
\" but WITHOUT ANY WARRANTY; without even the implied warranty of
\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
\" GNU General Public License for more details.
\"
\" You should have received a copy of the GNU General Public License
\" along with this program; if not, write to the Free Software
\" Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
\" =========================================================================
.TH LLSEARCH 1 \" -*- nroff -*-
.SH NAME
llsearch \- Search a GNIS file for place names within a given block of latitude/longitude
.SH SYNOPSIS
.B llsearch
latitude_low longitude_low latitude_high longitude_high
.SH DESCRIPTION
The U.S. Geological Survey supports sites on the Internet with
Geographic Names Information System (GNIS) files.
These files contain lists of place names, complete with their latitude/longitude and other information.
There is generally one file per U.S. state, and each file contains many, many, many place names.
If you want to use this data with
.I drawmap,
it is useful to reduce the data to only the items that you need.
.I Llsearch
lets you filter a GNIS file and winnow out only those place names that fall within
the latitude/longitude boundaries that you specify.
Latitudes and longitudes are positive for north latitude and east longitude, and negative
for south latitude and west longitude.
.I Llsearch
expects you to enter them in decimal degrees.
(The latitudes and longitudes in the GNIS file are in degrees-minutes-seconds format, followed
by 'N', 'S', 'E', or 'W'. However, there are two available file formats, and one of the formats
also contains the latitudes/longitudes in decimal degrees.)
Typical usage is as follows:
.TP
gunzip -c california.gz | llsearch 33 -118 34 -117 > gnis_santa_ana_west
.PP
Once you have reduced the data to some subset of interest, you can search for
particular items via the
.I grep
or
.I perl
commands, or you can simply edit the results with your favorite text editor.
The search commands are useful in reducing the sheer volume of data to
a more manageable size (by extracting, say, all mountain summits or all
streams), but you will probably ultimately end up looking through the remaining
data manually.
There is considerable
redundancy in place names, and human intelligence is useful in sorting
things out. While I was writing
.I drawmap
and
.I llsearch,
I frequently gazed out my office window, where I could spot at least
two, and possibly three Baldy Mountains. There are also quite a
few Beaver Creeks, Bear Canyons, Saddle Buttes, and Springfields out there.
By taking a close look at the information associated with each place name,
you can find the particular locations that interest you.
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