One of the best features of nnBackup is ability to fine-tune the program's behavior to suit your specific needs. Settings of nnBackup are stored in a configuration file named backup.ini. Most of command line options have corresponding variables in backup.ini which define the default behavior of the program and make it unnecessary to use the same command line options over and over again (see Variables Set in backup.ini).
At startup, nnBackup first tries to find backup.ini in the current working directory, then in the HomeDir and if it fails to find it there, it checks the nnBackup's program directory (where nnbackup.exe has been started). This allows you to specify not just global nnBackup's variables, but also "local" variables, used in processing specific directories. Use exclusive masks (e.g. -x *backup.ini) to avoid copying configuration files when copying the rest of the files in a directory.
You can state explicitly in the command line which configuration file should be used by nnBackup. For this purpose you can use command line option -ini.
It is important to keep in mind that command line options (and options listed in a text file with startup parameters) have higher priority that variables in backup.ini. In other words, command line options override variables of backup.ini; it was arranged this way in order to enable users to cancel certain variables of backup.ini for a particular backup session.