man FSCK

NAME
       fsck - check and repair a Linux file system

SYNOPSIS
       fsck [-lsAVRTMNP] [-C [fd]] [-t fstype] [filesys...]  [--] [fs-specific-options]

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 handle filesystems on different physical disk drives in parallel to reduce the total amount of time
       needed to check all of the filesystems.

       If no filesystems are specified on the command line, and the -A option is not specified, fsck  will  default  to  checking  filesystems  in
       /etc/fstab serially.  This is equivalent to the -As options.

       The exit code returned by fsck is the sum of the following conditions:
            0    - No errors
            1    - File system errors corrected
            2    - System should be rebooted
            4    - File system errors left uncorrected
            8    - Operational error
            16   - Usage or syntax error
            32   - Fsck canceled by user request
            128  - Shared library error
       The exit code returned when multiple file systems are checked is the bit-wise OR of the exit codes for each file system that is checked.

       In  actuality,  fsck  is simply a front-end for the various file system checkers (fsck.fstype) available under Linux.  The file system-spe‐
       cific checker is searched for in /sbin first, then in /etc/fs and /etc, and finally in the directories listed in the PATH environment vari‐
       able.  Please see the file system-specific checker manual pages for further details.