unterschied zwischen fetchmail -d0 -f und -d0 -f -a -v

-f <pathname> | --fetchmailrc <pathname>  
  Specify a non-default name for the ~/.fetchmailrc run control file. The pathname argument must be either "-" (a single dash, meaning to read the configuration from standard input) or a filename. Unless the --version option is also on, a named file argument must have permissions no more open than 0600 (u=rw,g=,o=) or else be /dev/null.