The nerocmd command line utility can create an ISO or NRG image from a set of files from the command line by specifying "Image Recorder" as the drive name to record to. When you use this parameter, use the "--output_image" parameter to specify the name of the ISO or NRG image.
Use the following command for creating an NRG file:
nerocmd --write --drivename "Image Recorder" --iso "(Volume name)" --output_image "(File name).nrg" --real --recursive "(Path to fileset)"
To create an ISO image instead of an NRG image, use the following command:
nerocmd --write --drivename "Image Recorder" --iso "(Volume name)" --output_image "(File name).iso" --real --tao --recursive "(Path to fileset)"
Replace "(Volume Name)" with the name of the volume to call this, replace "(File name)" with the path & name of what to call the ISO or NRG file and finally replace "(Path to fileset)" with the path to the folder containing the files you wish to place in the ISO image.
To prevent the process from looking for any user interaction, such as if you place this into a batch file or execute it from an application and for some reason the utility is run with a missing parameters, add the argument "--no_user_interaction".