[GRASS-user] Error and correction for v.swathwidth

[Patton, Eric]

David,

I was testing out your script v.swathwidth and I ran into an error. I took a
look at your code and inserted echo comments and sleep statements to slow
the execution of the program down so I could see where the error was
occurring. It looks like the program is choking on the "2>&1 > /dev/null"
statement on the r.mapcalc line:

GRASS 6.1.cvs (FundyBathy):~/coderepo > v.swathwidth trackline=Drumlin_Line
elevation=Drumlins_10m_fill beamwidth=5.5 distance=100
out=Drumlin_Line_swath --o

invalid map: dev  #Critical error occurs here
invalid map: null
Syntax error
Completed r.mapcalc...

Building topology ...
1154 primitives registered
Building areas:  100%
0 areas built
0 isles built
Attaching islands:
Attaching centroids:  100%
Topology was built.
Number of nodes     :   1154
Number of primitives:   1154
Number of points    :   1154
Number of lines     :   0
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   0
Number of isles     :   0
1154 points written to output map

Completed v.to.points...

Completed v.db.addcol...
ERROR: Cannot find raster map

Completed v.what.rast...
Lines buffers ...  100%

Building parts of topology ...
Building topology ...
0 primitives registered
Topology was built.
Number of nodes     :   0
Number of primitives:   0
Number of points    :   0
Number of lines     :   0
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   -
Number of isles     :   -
Snapping boundaries ...
All vertices:     0
Registered points (unique coordinates):     0
Nodes marked as anchor     :     0
Nodes marked to be snapped :     0
Snapped vertices :     0
New vertices     :     0
Breaking boundaries ...
Intersections:     0
Removing duplicates ...
Duplicates:     0
Attaching islands ...
Building topology ...
0 areas built
0 isles built
Attaching islands:
Topology was built.
Number of nodes     :   0
Number of primitives:   0
Number of points    :   0
Number of lines     :   0
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   0
Number of isles     :   0
Attaching centroids ...
Building topology ...
Attaching centroids: Topology was built.
Number of nodes     :   0
Number of primitives:   0
Number of points    :   0
Number of lines     :   0
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   0
Number of isles     :   0
Rebuilding topology ...
Building topology ...
0 primitives registered
0 areas built
0 isles built
Attaching islands:
Attaching centroids: Topology was built.
Number of nodes     :   0
Number of primitives:   0
Number of points    :   0
Number of lines     :   0
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   0
Number of isles     :   0

Completed v.buffer...
+---------------------------------+---------------+
| Tool                            | Threshold     |
+---------------------------------+---------------+
| Break                           |  0.000000e+00 |
+---------------------------------+---------------+
Copying vector lines ...
--------------------------------------------------
Rebuilding parts of topology ...
Building topology ...
0 primitives registered
Topology was built.
Number of nodes     :   0
Number of primitives:   0
Number of points    :   0
Number of lines     :   0
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   -
Number of isles     :   -
--------------------------------------------------
Tool: Break lines at intersections
Intersections:     0
--------------------------------------------------
Rebuilding topology for output vector ...
Building topology ...
0 primitives registered
0 areas built
0 isles built
Attaching islands:
Attaching centroids: Topology was built.
Number of nodes     :   0
Number of primitives:   0
Number of points    :   0
Number of lines     :   0
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   0
Number of isles     :   0

Completed v.clean...

Completed v.category...

Writing attributes ...
Removing duplicate centroids ...Building topology ...
0 primitives registered
0 areas built
0 isles built
Attaching islands:
Attaching centroids: Topology was built.
Number of nodes     :   0
Number of primitives:   0
Number of points    :   0
Number of lines     :   0
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   0
Number of isles     :   0

Completed v.extract...

RENAME [temp_circles4] to [Drumlin_Line_swath]
WARNING: The vector 'Drumlin_Line_swath' already exists and will be
         overwritten.
Swath width map written to: Drumlin_Line_swath


Commenting out the 2>&1 /dev/null part of your r.mapcalc line fixes the
error, and the program completes successfully.

~ Eric.