fcuk is a rather blatant abbreviation for a few different things, but I'm not aware of any server definition associated with it. You might be looking for fsck however, which is, according to about.com:
DESCRIPTION fsck is used to check and optionally repair one or more Linux file systems. filesys can be a device name (e.g. /dev/hdc1, /dev/sdb2), a mount point (e.g. /, /usr, /home), or an ext2 label or UUID specifier (e.g. UUID=8868abf6-88c5-4a83-98b8-bfc24057f7bd or LABEL=root). Normally, the fsck program will try to run filesystems on different physical disk drives in parallel to reduce total amount time to check all of the filesystems.
In lamens terms: The linux equivilant of Scandisc, but more powerful (or so it would seem).