missed to paste the error on dos command prompt. here it is -
D:\Downloads>cat VBox_EM12R3_1of3.ova VBox_EM12R3_2of3.ova VBox_EM12R3_3of3.ova
'cat' is not recognized as an internal or external command,
operable program or batch file.
On Windows you can concatenate the 3 ova files from the command line with the following command:
type VBox_EM12R3_1of3.ova VBox_EM12R3_2of3.ova VBox_EM 12R3_3of3.ova > EM12cR3VM.ova
On my laptop, it took quite a while.
Hope that helps.
you could try the following:
type VM1.ova VM2.ova VM3.ova > VM.ova
D:\DATA\Downloads\EM12cR3>type VBox_EM12R3_1of3.ova VBox_EM12R3_2of3.ova VBox_EM 12R3_3of3.ova > EM12cR3VM.ova