Sed: get lines beginning with some prefix

Try doing this :

awk '/^RIM-COD/' file.txt

Or

grep "^RIM-COD" file.txt

Or

sed -n '/^RIM-COD/p' file.txt

Use sed -n and only print lines that match RIM-COD.

sed -n -e '/^RIM-COD-/p' yourfile.txt