Length of lines

[N R A]

Can anyone help on this query - I've loaded our rivers as a vector data 
set, but the users want to determine the length of river between two 
points. This is the length including all the bends, not just the 'as the 
crow flys' one.

Is there any GRASS function that can do this ?

Thanks for any help,

Steve Culshaw
NRA North West
e-mail : nra at cix.compulink.co.uk (use this for general usage)
or         sculshaw at cix.compulink.co.uk (Private - only checked at best 
biweekly)