From ‘man fsck’:
-N Don't execute, just show what would be done.
Options to different filesystem-specific fsck's are not standardized. If in doubt, please consult the man
pages of the filesystem-specific checker. Although not guaranteed, the following options are supported by most
file system checkers:
-n For some filesystem-specific checkers, the -n option will cause the fs-specific fsck to avoid attempting
to repair any problems, but simply report such problems to stdout. This is however not true for all
filesystem-specific checkers. In particular, fsck.reiserfs(8) will not report any corruption if given
this option. fsck.minix(8) does not support the -n option at all.
-n Open the filesystem read-only, and assume an answer of 'no' to all questions. Allows e2fsck to be used
non-interactively. This option may not be specified at the same time as the -p or -y options.
From: rhelv6-list-bounces redhat com [mailto:rhelv6-list-bounces redhat com]
On Behalf Of francis picabia
On Thu, Dec 21, 2017 at 2:48 PM, Tim Mooney <Tim Mooney ndsu edu> wrote:
Well, I think they make the -n/-N flag in fsck for some purpose other than don't do it.
It is designed to be run on a system to check it without modifying.
My conclusion is it is only useful for seeing an error such as orphaned
inodes which are persistent across multiple runs of fsck -n
If there are other checksums and such that don't seem correct, that would be expected
on a live filesystem.