[GRASS5] [bug #3302] (grass) cs2cs with GRASS and NTv2 grid fails

[Harmish Bowman via RT]

`g.proj -jf` fails to report path to GRASS's grid files, so using it in a
cs2cs command string fails.

> A solution seems to be changing the output of 'g.proj -j' to prepend
> "$GISBASE/etc/nad/" to the grid file name


g.proj uses PROJ.4's pj_get_def() to get the string, then loops through it
printing one char at a time & replacing ' ' with '\n' if you didn't chose the
-f flat output flag. How to parse for "+nadgrids=" within the string and
replace with "+nadgrids=$GISBASE/etc/nad/"? (verbatim) Then we can use cs2cs
automatically in scripts, etc.

cs2cs needs the full path to the grid file if it isn't in PROJ's PROJ_LIB dir.
Setting the enviro variable to anything but PROJ's default pretty much breaks
PROJ. If the full path to the grid file is given, this isn't a problem.

Finding & placing the GRASS grid files in wherever PROJ is doesn't seem like a
robust solution.

"$GISBASE/etc/nad/" is obviously a GRASSism, so it has to be changed in GRASS
and not PROJ.4. (?)



thanks,
Hamish


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