fsck原理

 

  fsck在文件系统结构检查上做的动作基本等同于PC上的scandisk，当发现有占用的inode，但没有相应的file entry，就是说第一个inode没了，造成某些空间被占用，但没有任何合法的文件、目录指向它，此所谓lost。这些空间就被赋予一个inode头，做成一个文件，此所谓found，被放进lost+found目录

Generally, fsck is run automatically at boot time when the operating system detects that a file system is in an inconsistent state, indicating a non-graceful shutdown, such as a or power loss. As the command must be tailored specifically to the design of the file system, the exact behavior of various fsck implementations will vary. Typically, fsck utilities provide options for either interactively repairing damaged file systems (the user must decide how to fix specific problems), automatically deciding how to fix specific problems (so the user doesn't have to answer any questions), or reviewing the problems that need to be resolved on a file system without actually fixing them.

A can also run fsck manually if there is believed to be a problem with the file system. Because running fsck to repair a file system which is mounted for read/write operations can potentially cause severe data corruption/loss, the file system is normally checked while unmounted, mounted read-only, or with the system in a special maintenance mode that limits the risk of such damage.

A is designed such that tools such as fsck do not need to be run after unclean shutdown (i.e. crash). The Filesystem in has background fsck, so it is usually not necessary to wait for fsck to finish before accessing the disk.

The equivalent programs are and .