DISPLAY not set.Set DISPLAY environment variable, then re-run.
Cause:
Display variable is not set and so dbca cannot be invoked
[oracle@dgprim01 bin]$ ./dbca
DISPLAY not set.
Set DISPLAY environment variable, then re-run.
[oracle@dgprim01 bin]$ export DISPLAY=localhost:10.0
Workaround:
Set DISPLAY variable
[oracle@dgprim01 bin]$ export DISPLAY=localhost:10.0
[oracle@dgprim01 bin]$ ./dbca