do you mean like loggin you're scans ? if so just do this make a directory if you wish

nmap -sS -v -O (ip address goes here) > /home/prodikal/scan.log/(what you call the file).txt &

that will log it in to a specific directory replacing prodikal with the name of you're home directory and the name of the directory where you want to log to NOTE you must be root for a lot of types of scan's