The command (executable) to run. This command can not have a user interface and can not wait for user input. If it does the plugin will just hang forever.
This is the argument that is passed to the executable. The string "%fin" will be replaced with the name of the incoming file and %fout will be replaced by the name of the outgoing file. E.g. the command line '--compress -i "%fin" -o "%fout"' will be executed as '--compress -i "/tmp/input.txt" -o "/tmp/output.txt"' if the files happen to be located in /tmp. Jitterbit decides where the files are located, you only have to specify where in the command line the input and output file names go. %relfin and %relfout should be used if only the leaf of the file name should be used.
If an extension is added to the output file, set it here. E.g. if your command automatically adds ".ext" to the output file specified in the command, set this data element to ".ext". This can also be used for commands that just take an input file but appends an extension to it, such as gzip.