[GRASSLIST:4835] close vector polylines

[Praktikant]

Hello,

I have imported a shape-file with lines and I want to create Polygons from
these lines.
The lines are arranged in a way that I only need to connect one end of the
line with the other end in order to close a polygon.

1. Is there a modul that automizes this task (connecting one end of a line
with the other end of the same line)?

2. How can I assign a single Value to the polygons created in the procedure
mentioned in 1. ?

Thank you for any helpful suggestions.

Richard