Directories/folders you wish to open and compare in UltraCompare must be specified on the command line as follows:
uc - d c:\ temp\test c:\temp\test1
The - d flag indicates that directories/folders, and not files, should be opened for comparison.
If UltraCompare has NOT been added to your PATH you would need to reference the full path to the application in order to invoke it from the command line, i.e.:
" c:\program files\ultracompare\uc" - d c:\ temp\test c:\temp\test1
Please note that only UltraCompare Pro supports Command Line Options. UltraCompare Lite does not support opening/comparing directories/folders.