Flushing stdout is not going to help with this problem.
As I said in comment #17, the error is caused by /etc/init.d/dkms_autoinstaller sending text to debconf via stdout.
Flushing output within /etc/kernel/postinst.d/nvidia-common won't undo that error.
Debconf has already gotten the bad command before /etc/kernel/postinst.d/nvidia-common is started.
Patching /etc/kernel/postinst.d/dkms to redirect stdout DOES FIX the problem.
Adding "1>&2" to the invocation of /etc/init.d/dkms_autoinstaller keeps stdout clean.
Flushing stdout is not going to help with this problem. d/dkms_ autoinstaller sending text to debconf via stdout. postinst. d/nvidia- common won't undo that error. postinst. d/nvidia- common is started.
As I said in comment #17, the error is caused by /etc/init.
Flushing output within /etc/kernel/
Debconf has already gotten the bad command before /etc/kernel/
Patching /etc/kernel/ postinst. d/dkms to redirect stdout DOES FIX the problem. d/dkms_ autoinstaller keeps stdout clean.
Adding "1>&2" to the invocation of /etc/init.