10-03-2004
If you can create a readable version of the special file that corresponds to a mounted filesystem, you could then read the raw disk to learn the contents of all of the files. If it's writable, you can destroy the filesystem. Reading a private version of /dev/mem would let you view kernel structures. A writable version of /dev/mem would allow you to easily crash the system. All "mesg n" does is render a tty device file unwritable. If you can create your own copy, you can bypass that. The list goes on...
fsck changes stuff on the disk. A mounted file system has stuff in core. When the in core stuff gets flushed it will conflict with the changes made by fsck. Also think about an allocated inode which in not in a directory. That could be perfectly ok for a mounted file system. But it's an error if it happens on an unmounted filesystem. fsck is designed to treat that as an error.
There are ways to see what a filesystem looks like now. And some of them are usable by normal users. But you can't see the way it used to be. If you captured some info before that change, you might have a shot. But you won't be able to see historical data. And not everything changable by root is viewable by normal users.
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LEARN ABOUT HPUX
fsck.minix
FSCK.MINIX(8) System Administration FSCK.MINIX(8)
NAME
fsck.minix - check consistency of Minix filesystem
SYNOPSIS
fsck.minix [options] device
DESCRIPTION
fsck.minix performs a consistency check for the Linux MINIX filesystem.
The program assumes the filesystem is quiescent. fsck.minix should not be used on a mounted device unless you can be sure nobody is writ-
ing to it. Remember that the kernel can write to device when it searches for files.
The device name will usually have the following form:
/dev/hda[1-63] IDE disk 1
/dev/hdb[1-63] IDE disk 2
/dev/sda[1-15] SCSI disk 1
/dev/sdb[1-15] SCSI disk 2
If the filesystem was changed, i.e., repaired, then fsck.minix will print "FILE SYSTEM HAS CHANGED" and will sync(2) three times before
exiting. There is no need to reboot after check.
WARNING
fsck.minix should not be used on a mounted filesystem. Using fsck.minix 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.minix on a
mounted filesystem, such as the root filesystem, make sure nothing is writing to the disk, and that no files are "zombies" waiting for
deletion.
OPTIONS
-l, --list
List all filenames.
-r, --repair
Perform interactive repairs.
-a, --auto
Perform automatic repairs. This option implies --repair and serves to answer all of the questions asked with the default. Note
that this can be extremely dangerous in the case of extensive filesystem damage.
-v, --verbose
Be verbose.
-s, --super
Output super-block information.
-m, --uncleared
Activate MINIX-like "mode not cleared" warnings.
-f, --force
Force a filesystem check even if the filesystem was marked as valid. Marking is done by the kernel when the filesystem is
unmounted.
-V, --version
Display version information and exit.
-h, --help
Display help text and exit.
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.minix will print "unable to read super block". If the device exists, but is not a MINIX filesystem,
fsck.minix will print "bad magic number in super-block".
EXIT CODES
The exit code returned by fsck.minix is the sum of the following:
0 No errors
3 Filesystem errors corrected, system should be rebooted if filesystem was mounted
4 Filesystem errors left uncorrected
7 Combination of exit codes 3 and 4
8 Operational error
16 Usage or syntax error
AUTHORS
Linus Torvalds <torvalds@cs.helsinki.fi>
Error code values by Rik Faith <faith@cs.unc.edu>
Added support for filesystem valid flag: Dr. Wettstein <greg%wind.uucp@plains.nodak.edu>.
Check to prevent fsck of mounted filesystem added by Daniel Quinlan <quinlan@yggdrasil.com>.
Minix v2 fs support by Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>, updated by Nicolai Langfeldt <janl@math.uio.no>.
Portability patch by Russell King <rmk@ecs.soton.ac.uk>.
SEE ALSO
fsck(8), fsck.ext2(8), mkfs(8), mkfs.ext2(8), mkfs.minix(8), reboot(8)
AVAILABILITY
The fsck.minix command is part of the util-linux package and is available from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils
/util-linux/>.
util-linux June 2015 FSCK.MINIX(8)