--- name: "v.external.out" section: "1grass" platform: "linux" package: "grass-doc" version: "8.4.1-1" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/v.external.out" --- # v.external.out(1grass) Defines vector output format. ## NAME **v.external.out** - Defines vector output format. ## KEYWORDS vector, export, output, external, OGR, PostGIS ## SYNOPSIS **v.external.out**\ **v.external.out --help**\ **v.external.out** \[-**frpg**\] \[**output**=*string*\] \[**format**=*string*\] \[**options**=*string*\[,*string*,...\]\] \[**loadsettings**=*name*\] \[**savesettings**=*name*\] \[--**overwrite**\] \[--**help**\] \[--**verbose**\] \[--**quiet**\] \[--**ui**\] ### Flags: - **-f** List supported formats and exit - **-r** Cease using OGR/PostGIS, revert to native output and exit - **-p** Print current status - **-g** Print current status in shell script style - **--overwrite** Allow output files to overwrite existing files - **--help** Print usage summary - **--verbose** Verbose module output - **--quiet** Quiet module output - **--ui** Force launching GUI dialog ### Parameters: - **output**=*string* Name of output directory or OGR or PostGIS data source\ Examples:\         ESRI Shapefile: directory containing a shapefile\         MapInfo File: directory containing a mapinfo file\         PostGIS database: connection string, eg. ’PG:dbname=db user=grass’ - **format**=*string* Format for output vector data\ Options: *AmigoCloud, BAG, CSV, Carto, DGN, DXF, ESRI\_Shapefile, Elasticsearch, FITS, FlatGeobuf, GML, GPKG, GPSBabel, GPX, GeoJSON, GeoJSONSeq, GeoRSS, Geoconcept, Interlis\_1, Interlis\_2, JML, JSONFG, KML, LIBKML, MBTiles, MSSQLSpatial, MVT, MapInfo\_File, MapML, Memory, MiraMonVector, MySQL, NGW, ODS, OGR\_GMT, OpenFileGDB, PCIDSK, PDF, PDS4, PGDUMP, PMTiles, PostgreSQL, S57, SQLite, Selafin, VDV, VICAR, WAsP, XLSX, netCDF*\ Default: *ESRI\_Shapefile* - **options**=*string\[,string*,...\] Creation options\ Examples:\         ’SHPT=POINTZ’: create 3D point Shapefile data\         ’GEOM\_TYPE=geography’: use geography PostGIS data\         ’SCHEMA=grass’: create new PostGIS tables in ’grass’ schema - **loadsettings**=*name* Name of input file to read settings from - **savesettings**=*name* Name for output file where to save current settings ## DESCRIPTION *v.external.out* instructs GRASS to write vector maps in external data format (e.g. ESRI Shapefile, Mapinfo, and others) using OGR library. PostGIS data can be also written by built-in GRASS-PostGIS data provider. ## NOTES Number of available output formats (`v.external.out -f`) depends on OGR installation. ’PostgreSQL’ format is presented also when GRASS comes with PostgreSQL support (check for ’--with-postgres’ in `g.version -b` output). To store geometry and attribute data in PostGIS database (’PostgreSQL’ format) GRASS uses built-in *GRASS-PostGIS data* *provider*. PostGIS data can be written also by OGR library when `GRASS_VECTOR_OGR` environmental variable is defined or GRASS is not compiled with PostgreSQL support. Creation **options** refer to the output format specified by **format** option. See the list of valid creation options at OGR formats specification page, example for ESRI Shapefile or PostgreSQL/PostGIS format (section "Layer Creation Options"). Options are comma-separated pairs (`key=value`), the options are case-insensitive, eg. `options="SCHEMA=myschema,FID=cat"`. ### PostgreSQL/PostGIS Creation Options Note that built-in *GRASS-PostGIS data provider* (**format=PostgreSQL**) supports different creation **options** compared to PostgreSQL/PostGIS driver from OGR library: - • `SCHEMA=` - name of schema where to create feature tables. If schema doesn’t exists, it’s automatically created when writing PostGIS data. - • `FID=` - name of column which will be used as primary key (feature id), default: `fid` - • `GEOMETRY_NAME=` name of column which will be used for storing geometry data in feature table, default: `geom` - • `SPATIAL_INDEX=YES|NO` - enable/disable spatial index on geometry column, default: YES - • `PRIMARY_KEY=YES|NO` - enable/disable primary key on FID column, default: YES - • `SRID=` - spatial reference identifier, default: not defined - • `TOPOLOGY=YES|NO` - enable/disable native PostGIS topology, default: NO Options relevant only to topological output (`TOPOLOGY=YES`): - • `TOPOSCHEMA_NAME=` - name of PostGIS Topology schema (relevant only for `TOPOLOGY=YES`), default: `topo_` - • `TOPOGEOM_NAME=` - name of column which will be used for storing topogeometry data in feature table, default: `topo` - • `TOPO_TOLERANCE=` - tolerance for PostGIS Topology schema, see CreateTopology function for defails, default: `0` - • `TOPO_GEO_ONLY=YES|NO` - store in PostGIS Topology schema only data relevant to Topo-Geo data model, default: `NO` - • `SIMPLE_FEATURE=YES|NO` - build simple features geometry in `GEOMETRY_NAME` column from topogeometry data, default: NO Note that topological output requires **PostGIS version 2 or later**. ## EXAMPLES ### ESRI Shapefile *v.external.out* can be used along with *v.external* to process external geodata in GRASS while writing out the results directly eg. in ESRI Shapefile format:\ ``` # register Shapefile in GRASS mapset: v.external input=/path/to/shapefiles layer=cities # define output directory for GRASS calculation results: v.external.out output=$HOME/gisoutput # do something (here: spatial query), write output directly as Shapefile v.select ainput=cities atype=point binput=forests btype=area operator=within output=fcities ``` Current settings can be printed using **-p** or **-g** flag.\ ``` v.external.out -p output: /path/to/home/gisoutput format: ESRI Shapefile ``` ### PostGIS (simple features) PostGIS data can be accessed directly using *GRASS-PostGIS data* *provider* (GRASS must be compiled with PostgreSQL support).\ ``` # register PostGIS table in GRASS mapset: v.external output=PG:dbname=gisdb layer=cities # define output PostGIS database for GRASS calculation results stored as simple features: v.external.out output=PG:dbname=gisdb format=PostgreSQL # do some processing... ``` *Note:* If the environment variable `GRASS_VECTOR_OGR` is defined, or GRASS is compiled without PostgreSQL support then GRASS will use PostgreSQL driver from OGR library for reading and writing PostGIS data. ### PostGIS Topology ``` # define output PostGIS database for GRASS calculation results stored as topological elements: v.external.out output=PG:dbname=gisdb format=PostgreSQL options=topology=YES # do some processing... ``` *Note:* PostGIS topological access is supported only in built-in *GRASS-PostGIS data provider*. ### GRASS native format To restore original settings, ie. use the GRASS native format, type:\ ``` v.external.out -r ``` ### Restore settings Current settings can be stored to file by specifying **output** option.\ ``` # define output PostGIS database for GRASS calculation with # results stored as topological elements: v.external.out output=PG:dbname=gisdb format=PostgreSQL \ options=topology=YES savesettings=gisdb_topo.txt # ... and do some processing in PostGIS Topology ``` Back to native format:\ ``` v.external.out -r # do some processing in native format ``` Restore previous settings from "gisdb\_topo.txt" file by specifying **loadsettings** option.\ ``` v.external.out loadsettings=gisdb_topo.txt # ... and do some processing in PostGIS Topology ``` ## REFERENCES - • GRASS-OGR data provider - • OGR vector library C API documentation - • GRASS-PostGIS data provider - • libpq - C Library ## SEE ALSO *v.external,* *v.in.ogr,* *v.out.ogr,* *v.out.postgis* See also GRASS user wiki page for more examples. ## AUTHOR Martin Landa, Czech Technical University in Prague, Czech Republic (development supported by Fondazione Edmund Mach and Comune di Trento, Italy) ## SOURCE CODE Available at: v.external.out source code (history) Accessed: Monday Feb 24 17:51:27 2025 Main index \| Vector index \| Topics index \| Keywords index \| Graphical index \| Full index © 2003-2025 GRASS Development Team, GRASS GIS 8.4.1 Reference Manual