Install GRASS extension with g.extension and Rstudio

Question

I want to use GRASS in Rstudio to crop my DEM with my GRASS region definited. I tried to install r.clipextension on GRASS with g.extension to realise this. But when I use the function g.extension to import r.clip in GRASS I have error ERREUR : Variable 'LOCATION_NAME' non définie. My code is :

install.packages("rgrass7")
library(rgrass7)

# Creation Grass environment 
initGRASS("C:/Program Files/GRASS GIS 7.6",
          override = TRUE,
          gisDbase = "GRASS_TEMP",
          home = tempdir(),
          mapset = "PERMANENT",
          remove_GISRC = TRUE)

# To install extension 
execGRASS(cmd = "g.extension",
          flags = "s",
          parameters = list(extension = "r.clip", operation = "add"))

And the code to install extension return this error :

> execGRASS(cmd = "g.extension",
+           flags = "s",
+           parameters = list(extension = "r.clip", operation = "add"))

ATTENTION: Extension <r.clip> already installed. Re-installing...
Downloading precompiled GRASS Addons <r.clip>...
ERREUR :Variable 'LOCATION_NAME' non définie
ERREUR :Variable 'LOCATION_NAME' non définie
ERREUR :Variable 'LOCATION_NAME' non définie
Traceback (most recent call last):
  File "C:/Program Files/GRASS GIS 7.6/scripts/g.extension.py", line 1748, in <module>
    sys.exit(main())
  File "C:/Program Files/GRASS GIS 7.6/scripts/g.extension.py", line 1727, in main
    install_extension(source=source, url=url, xmlurl=xmlurl)
  File "C:/Program Files/GRASS GIS 7.6/scripts/g.extension.py", line 702, in install_extension
    blist = install_extension_xml(xmlurl, mlist)
  File "C:/Program Files/GRASS GIS 7.6/scripts/g.extension.py", line 922, in install_extension_xml
    write_xml_modules(xml_file, tree)
  File "C:/Program Files/GRASS GIS 7.6/scripts/g.extension.py", line 601, in write_xml_modules
    libgis_revison = grass.version()['libgis_revision']
KeyError: 'libgis_revision'

> execGRASS(cmd = "r.clip",
+           flags = "overwrite",
+           parameters = list (input = "GRASS_MNS",
+                              output = "GRASS_MNT_crop"))

Error : XML content does not seem to be XML: ' No such file or directory'
De plus : Warning message:
In system(cmd0, intern = TRUE) :
  l'exécution de la commande 'r.clip.bat --interface-description' renvoie un statut 2
Error in parseGRASS(cmd, legacyExec = legacyExec) : r.clip not parsed

When I check the manuel of the g.extension function, I saw that -s argument in flags can to be use but the system administrator rights are necessary. So I have given the right at my folder where GRASS 7.6 is installed and I'm administrator of my computer.

When I install r.clip in Grass interface, installation is successfully finished but it's impossible to find r.clip extension in extension list of Grass.

But when I research r.clip extension in Rstudio with code below, I find it !

> execGRASS(cmd = "g.extension",
+           flags = "l")

ATTENTION: GRASS_ADDON_BASE is not defined, installing to ~/.grass7/addons
List of available extensions (modules):
r.clip
...

I use GRASS 7.6.1 installed in C:/Program Files/GRASS GIS 7.6 and R 3.6.1.

Answer 1

GRASS extensions should be manually downloaded and installed on MS Windows.

• Download r.clip from here: https://wingrass.fsv.cvut.cz/grass76/x86_64/addons/grass-7.6.1/ (since you have 7.6).
• Unzip the files in YOUR_USER\AppData\Roaming\GRASS7\addons

Now r.clip should work.