[GRASSLIST:3890] How to generate merge key in Grass to enable merging data in R?

[Craig Aumann]

In more detail, I have read some vector data containing lines into
GRASS:
----------------------

SHPDIR=/home/caumann/amedata/evergreen/data
DBFDIR=/home/caumann/amedata/evergreen/data

SHPFILE="seismic"
DBFFILE="seismic"
ATT=_att

ATTNAME="$SHPFILE$ATT"
    
echo "$SHPFILE"
echo "$DBFFILE"
    
v.in.ogr -o dsn="$SHPDIR" output="$SHPFILE" layer="$SHPFILE"

db.copy from_driver=dbf from_database=$DBFDIR \
    from_table=$DBFFILE \
    to_driver=pg to_database="dbname=alpac_netdown,user=caumann" \
    to_table=$ATTNAME

v.db.connect -o  map="$SHPFILE" table="$ATTNAME" key=LINK_KEY \
driver=pg database="dbname=alpac_netdown,user=caumann"

v.out.ascii input="$SHPFILE" output=seismic.txt

----------------------------

What I then do is read the text file "seismic.txt" into R and find the
center of the line.  What I want to do now is link these centers to the
attribute data which is sitting in the attribute database.  Reading the
attribute database into R is easy:

-----------
conn <- dbConnect(PgSQL(), dbname="alpac_netdown", user="caumann")
dbListTables(conn)
seis <- dbReadTable(conn, "seismic_att")
dbDisconnect(conn)
-----------

What I can't figure out is how to create a unique "key" in BOTH the
attribute database "seismic_att" AND in the exported shape file
"seismic.txt" so I can then link the line centers created in R to the
associated attribute information for a given line using that key. 

I hope this is trivial...  Its just that I can't figure it out what I
need to do on the GRASS57 side of things!

Cheers!
Craig