Creating new layer with only subset of polygons of existing layer in GRASS?

Question

Suppose I have a map with 10,000 polygons with categories 1 to 10,000 in layer 1. I would like to create a second layer with only the features in layer 1 with categories 1 to 5,000. From the online documentation, it seems I can do it with a combination of v.category, v.to.db and v.db.connect. But v.category does not provide a filtering mechanism when creating a new layer. It seems doable from this link, specifically:

If a vector object has zero categories in a layer, then it does not appear in that layer. In this fashion some vector objects may appear in some layers but not in others. Taking the example of the fields and paths, only some boundaries, but not all, might have a category value in layer 2.

I googled very hard but did not find a single example so far.

Answer 1

Maybe this will help:

# First get the id's of the polygon map with categories 1-5000
ids=$(v.edit polys tool=select cats=1-5000)
Selecting features...
5000 of 30091 features selected from vector map <polys@Arava>
v.edit complete.
# Now use v.category and filter by ids
v.category polys ids=$ids option=add layer=2 output=polys2
# and check:
v.category polys2 option=report
Layer/table: 1/polys2
type       count        min        max
point          0          0          0
line           0          0          0
boundary       0          0          0
centroid    8123          1       8123
area           0          0          0
face           0          0          0
kernel         0          0          0
all         8123          1       8123
Layer: 2
type       count        min        max
point          0          0          0
line           0          0          0
boundary       0          0          0
centroid    5000          1       5000
area           0          0          0
face           0          0          0
kernel         0          0          0
all         5000          1       5000

Note that there's no database connection for layer 2 now.

v.db.connect -p polys2
Vector map <polys2> is connected by:
layer <1/polys2> table <polys2> in database </home/micha/GIS/grass/ITM/Arava/sqlite.db> through driver <sqlite> with key <cat>