ﬁle is not a block or character device OK You have given fsck a regular ﬁle name by mistake. Check the type of the ﬁle speciﬁed. Possible responses to the OK prompt are: YES ignore this error condition. NO ignore this ﬁle system and continues checking the next ﬁle system given. UNDEFINED OPTIMIZATION IN SUPERBLOCK (SET TO DEFAULT) The superblock optimization parameter is neither OPT_TIME nor OPT_SPACE. Possible responses to the SET TO DEFAULT prompt are: YES The superblock is set to request optimization to minimize running time of the system. (If optimization to minimize disk space utilization is desired, it can beset using tunefs(8).) NO ignore this error condition.