NAME

       v.external  - Creates a new vector as a read-only link to OGR layer.
       Available               drivers:               ESRI               Shapefile,MapInfo               File,UK
       .NTF,SDTS,TIGER,S57,DGN,VRT,REC,Memory,BNA,CSV,NAS,GML,GPX,LIBKML,KML,GeoJSON,Interlis         1,Interlis
       2,GMT,SQLite,DODS,ODBC,PGeo,MSSQLSpatial,OGDI,PostgreSQL,MySQL,PCIDSK,XPlane,AVCBin,AVCE00,DXF,Geoconcept,GeoRSS,GPSTrackMaker,VFK,PGDump,OSM,GPSBabel,SUA,OpenAir,PDS,WFS,HTF,AeronavFAA,Geomedia,EDIGEO,GFT,SVG,CouchDB,Idrisi,ARCGEN,SEGUKOOA,SEGY,XLS,ODS,XLSX,ElasticSearch,PDF

KEYWORDS

       vector, external, import

SYNOPSIS

       v.external
       v.external help
       v.external dsn=string  [output=name]   [layer=string]   [--overwrite]  [--verbose]  [--quiet]

   Flags:
       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       dsn=string
           OGR datasource name. Examples:
                     ESRI  Shapefile:  directory containing shapefiles        MapInfo File: directory containing
           mapinfo files

       output=name
           Output vector. If not given, available layers are printed only.

       layer=string
           OGR layer name. If not given, available layers are printed only. Examples:
                     ESRI Shapefile: shapefile name          MapInfo File: mapinfo file name

DESCRIPTION

       v.external creates new vector as a link to external OGR layer (read only).  OGR (Simple Features Library)
       is part of the GDAL library, so you need to install GDAL to use v.external and external OGR layers.

   Supported OGR Vector Formats
       ESRI Shapefile
       Mapinfo File

       Further available drivers such as UK .NTF, SDTS, TIGER, IHO S-57 (ENC), DGN, GML,  AVCBin,  REC,  Memory,
       OGDI, and PostgreSQL depend on the local installation (OGR library), for details see OGR web site.

EXAMPLES

       SHAPE files

       v.external dsn=/home/user/shape_data layer=test_shape output=grass_map

       MapInfo files

       v.external dsn=./ layer=mapinfo_test output=grass_map

       SDTS files (you have to select the CATD file)

       v.external dsn=CITXCATD.DDF output=cities

       TIGER files

       v.external dsn=input/2000/56015/ layer=CompleteChain,PIP output=t56015_all

       PostGIS maps (area example)

       v.external dsn="PG:host=localhost user=postgres dbname=postgis" layer=polymap \
       output=polygons

NOTES

       The  simple  feature  data model used by OGR is very different from the topological format used by GRASS.
       Instead of true topology, so called 'pseudo topology' is created for data  linked  by  v.external.   User
       should  learn  the difference between those to formats, because some modules working correctly with GRASS
       native data, can produce wrong results with input layers created by v.external.

       See v.db.connect for an example of maintaining attributes in external DBMS in also writable mode.

REFERENCES

       OGR vector library
       OGR vector library C API documentation

SEE ALSO

       v.clean, v.db.connect, v.in.db, v.in.ogr, v.out.ogr

AUTHOR

       Radim Blazek, ITC-Irst, Trento, Italy

       Last changed: $Date: 2012-02-25 05:38:11 -0800 (Sat, 25 Feb 2012) $

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       © 2003-2013 GRASS Development Team

GRASS 6.4.3                                                                                   v.external(1grass)