v.out.ascii(1)

📦
version 8.4.2 · 8 versions
, in fedora 44

v.out.ascii 💖

okay bestie, welcome to the GRASS GIS User's Manual, section 1, and today's main character is v.out.ascii — she exports a vector map into a GRASS ASCII vector representation. 💅

And like, super important: by default she only exports features that have a category. Want everything? Use layer=-1. periodt.

✨ KEYWORDS ✨

vector, export, output, ASCII 🦋

🌸 SYNOPSIS 🌸

v.out.ascii
v.out.ascii --help
v.out.ascii [-ocr] input=name  [layer=string]
[type=string[,string,...]]   [output=name]   [columns=name[,name,...]]
[cats=range]   [where=sql_query]  format=string  [separator=character]
[precision=integer]   [--overwrite]  [--help]  [--verbose]  [--quiet]
[--ui]

🎀 Flags 🎀

  • -o — make an old (version 4) ASCII file. vintage vibes, iykyk
  • -c — include the column names in the output (points mode)
  • -r — only export points that fall within the current 3D region (points mode)
  • --overwrite — let output files overwrite existing files, no cap
  • --help — print the usage summary
  • --verbose — verbose module output
  • --quiet — quiet module output 🤫
  • --ui — force launching the GUI dialog

🫶 Parameters 🫶

  • input=name [required] — name of the input vector map. Or a data source for direct OGR access.
  • layer=string — layer number or name (-1 for all layers). One single vector map can be connected to multiple database tables, and this number determines which table to use. When it's used with direct OGR access, this is the layer name. Default: 1
  • type=string[,string,...] — input feature type. Options: point, line, boundary, centroid, area, face, kernel. Default: point,line,boundary,centroid,area,face,kernel
  • output=name — name for the output ASCII file, or ASCII vector name if -o is defined. If it's not given, or it's -, then standard output. 📤
  • columns=name[,name,...] — name of attribute column(s) to export (point mode). "*" for all columns.
  • cats=range — category values. Example: 1,3,7-9,13
  • where=sql_query — WHERE conditions of an SQL statement without the where keyword. Example: income < 1000 and population >= 10000
  • format=string [required] — output format. Options: point, standard, wkt. Default: point
    • point: simple point format (point per row)
    • standard: GRASS ASCII vector format
    • wkt: OGC well-known text
  • separator=character — field separator. Field separator (points mode). Default: pipe
  • precision=integer — number of significant digits (floating point only). Options: 0-32. Default: 8

💜 DESCRIPTION 💜

v.out.ascii converts a GRASS vector map in binary format into a GRASS vector map in ASCII format. And if you use flag -o, the v.out.ascii output will be in the old (version 4) ASCII format. throwback fr fr

If the output parameter isn't given, then the data gets sent to standard output. easy peasy 🍓

👑 NOTES 👑

The v.in.ascii module does the exact opposite of v.out.ascii — it converts vector maps in ASCII format to their binary format. These two companion modules are lowkey iconic: they're useful both for importing and exporting vector maps between GRASS and other software, and for transferring data between machines. 🧚

If the old version is requested, the output files from v.out.ascii get placed in the $LOCATION/$MAPSET/dig_ascii/ and $LOCATION/$MAPSET/dig_att directory.

If layer > 0 then only features with a category number will be exported. Use v.category to add them if you need to, or define layer=-1 to also export features without a category. 💅

heads up bestie!! v.out.ascii in old version mode (-o) does not copy the dig_cats file associated with the binary vector input map to the new output file name. You have to copy the dig_cats file to the new output name yourself if you want that (e.g. using the UNIX cp command). no free rides 😭

Also: you can output the coordinates of vertices in a non-points vector feature — first convert the vector feature to a points map with v.to.points, and then export with v.out.ascii in points mode. glow up achieved ✨

🌈 EXAMPLES 🌈

⭐ Standard mode

See ASCII format specification.

v.out.ascii input=quads format=standard
ORGANIZATION: US Army Const. Eng. Rsch. Lab
DIGIT DATE:   May 1987
DIGIT NAME:   grass
MAP NAME:     Quads
MAP DATE:     May 1987
MAP SCALE:    24000
OTHER INFO:
ZONE:         13
MAP THRESH:   18.288000
VERTI:
B  4
 599587.1820962 4914067.53414294
 589639.15126831 4913922.5687301
 589440.96838162 4927803.62500018
 599375.87959179 4927959.83330436
B  2
 599375.87959179 4927959.83330436
 599587.1820962 4914067.53414294
B  4
 599587.1820962 4914067.53414294
 609541.5508239 4914236.0597482
 609316.10665227 4928116.8490555
 599375.87959179 4927959.83330436
C  1 1
 594125.63    4921115.58
 1     1
C  1 1
 604433.84    4921087.1
 1     2

🦋 Point mode

v.out.ascii input=quads format=point
594125.63|4921115.58|1
604433.84|4921087.1|2

Print also selected attributes:

v.out.ascii input=geodetic_pts format=point where="cat > 5 and cat <= 8" columns=GEOD_NAME
573638.06289275|271623.25042595|6|27 WC 6
574416.81289275|274116.65542595|7|27 WC 7
575301.31189275|275303.81342595|8|27 WC 8

To print all attributes type columns=*:

v.out.ascii input=geodetic_pts format=point where="cat > 5 and cat <= 8" columns=*
573638.06289275|271623.25042595|6|6|0.00000000|0.00000000|6|6|27 WC 6|573638.09200000|271623.24100000|0.00|0|1.00000000|1.00000000
574416.81289275|274116.65542595|7|7|0.00000000|0.00000000|7|7|27 WC 7|574416.84100000|274116.64900000|0.00|0|1.00000000|1.00000000
575301.31189275|275303.81342595|8|8|0.00000000|0.00000000|8|8|27 WC 8|575301.30600000|275303.82600000|0.00|0|1.00000000|1.00000000

💀 WKT mode

WKT is abbreviation for Well-known text.

v.out.ascii input=quads format=wkt
POLYGON((599587.18209620 4914067.53414294, 589639.15126831 4913922.56873010,
         589440.96838162 4927803.62500018, 599375.87959179 4927959.83330436,
         599587.18209620 4914067.53414294))
POLYGON((599587.18209620 4914067.53414294, 599375.87959179 4927959.83330436,
         609316.10665227 4928116.84905550, 609541.55082390 4914236.05974820,
         599587.18209620 4914067.53414294))

🔥 SEE ALSO 🔥

v.category, v.in.ascii, v.to.points

GRASS ASCII vector format specification GRASS SQL interface

💖 AUTHORS 💖

  • Michael Higgins, U.S. Army Construction Engineering Research Laboratory
  • James Westervelt, U.S. Army Construction Engineering Research Laboratory
  • Radim Blazek, ITC-Irst, Trento, Italy
  • Attribute selection added by Martin Landa, Czech Technical University in Prague, Czech Republic (2008/12)

🌟 SOURCE CODE 🌟

Available at: v.out.ascii source code (history)

Accessed: Saturday Jan 17 05:41:27 2026

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© 2003-2025 GRASS Development Team, GRASS GIS 8.4.2 Reference Manual

and that's the whole thing bestie!! 🎀 this page came straight out of GRASS 8.4.2, v.out.ascii(1), and yeah we read it all — ate and left no crumbs. mwah 💋 go export something iconic 🫶

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