sed - how to add something in front of line

1. marek@lati:/tmp$ cat test
marek
sed
awk
linux

2. make change only in output
marek@lati:/tmp$ sed 's/^/....../g' test
......marek
......sed
......awk
......linux

3. add few "." in the front of the line and save it to source file

marek@lati:/tmp$ sed -i 's/^/....../g' test
marek@lati:/tmp$ cat test
......marek
......sed
......awk
......linux