How to use fsck to repair file system errors in Linux Ubuntu 18.04,16.04,12.04.How to repair ubuntu Linux by fsck command.fsck fileslib. There is another scenario in which you have a LVM filesystem and you are unable to run the fsck command because your cannot activate LVM volume group in rescue mode i.e. Block Storage - iSCSI. In these cases, complete the following steps. The command "fsck" only run to unmounted filesystem. C. Check whether filesystem is used by any application. The fsck command (file system consistency check) is a utility to check and repair a Linux Filesystem. Modern file systems with journaling are designed such that tools like fsck are not readily required. However, in a few cases, fsck might be the only option to repair a 'bad' filesystem. fsck can be run on a partition that got corrupted or