FSCK(8)

NAME
fsck - a file system consistency checker for Linux

SYNOPSIS
fsck [ -larvsm ] device

DESCRIPTION
fsck performs a consistency check for the Linux MINIX filesystem. The current version supports the 14 character and 30 character filename options. The program assumes the file system is quiescent. fsck should not be used on a mounted device unless you can be sure nobody is writing to it (and remember that the kernel can write to it when it searches for files). The device will usually have the following form:
    /dev/hda[1-8]
    /dev/hdb[1-8]
    /dev/sda[1-8]
    /dev/sdb[1-8]
If the file system was changed (i.e., repaired), then fsck will print "FILE SYSTEM HAS CHANGED" and will sync(2) three times before exiting. Since Linux does not currently have raw devices, there is no need to reboot at this time (versus a system which does have raw devices).

WARNING
fsck should not be used on a mounted filesystem. Using fsck on a mounted filesystem is very dangerous, due to the possibility that deleted files are still in use, and can seriously damage a perfectly good filesystem! If you absolutely have to run fsck on a mounted filesystem (i.e., the root filesystem), make sure nothing is writing to the disk, and that no files are "zombies" waiting for deletion.

OPTIONS

-l  Lists all filenames

-r  Performs interactive repairs

-a  Performs automatic repairs (this option implies -r), and serves to answer all of the questions asked with the default. Note that this can be extremely dangerous in the case of extensive file system damage.

-v  Verbose

-s  Outputs super-block information

-m  Activates MINIX-like "mode not cleared" warnings

SEE ALSO
mkfs(8), efsck(8), emkfs(8), reboot(8)

DIAGNOSTICS
There are numerous diagnostic messages. The ones mentioned here are the most commonly seen in normal usage. If the device does not exist, fsck will print "unable to read super block". If the device exists, but is not a MINIX file system, fsck will print "bad magic number in super-block".

AUTHOR
Linus Torvalds (torvalds@cs.helsinki.fi)