fsck
Linux Command – fsck ใช้ในการตรวจสอบและซ่อมแซม file system
คำสั่ง
1. ตรวจสอบ file system และ disk partition
$ fsck /dev/sda6
fsck from util-linux 2.20.1
e2fsck 1.42 (29-Nov-2011)
/dev/sda6: clean, 95/2240224 files, 3793506/4476416 blocks
ผลลัพธ์ exit code ที่ได้มีดังนี้
- 0 – No errors
- 1 – Filesystem errors corrected
- 2 – System should be rebooted
- 4 – Filesystem errors left uncorrected
- 8 – Operational error
- 16 – Usage or syntax error
- 32 – Fsck canceled by user request
- 128 – Shared-library error
$ fsck /dev/sda2
fsck from util-linux 2.20.1
fsck: fsck.ntfs: not found
fsck: error 2 while executing fsck.ntfs for /dev/sda2
2. ตรวจสอบ file system ทั้งหมด
ใช้ option -A ในการตรวจสอบ file system ภายใต้ /etc/fstab ทั้งหมด
$ fsck -AR -y
fsck from util-linux 2.20.1
e2fsck 1.42 (29-Nov-2011)
/dev/sda6: clean, 95/2240224 files, 3793506/4476416 blocks
dosfsck 3.0.12, 29 Oct 2011, FAT32, LFN
/dev/sda7: 8 files, 50/1463400 clusters
3. ตรวจสอบเฉพาะ file system type ที่ต้องการ
ใช้ option -t
$ fsck -AR -t ext2 -y
fsck from util-linux 2.20.1
e2fsck 1.42 (29-Nov-2011)
/dev/sda6: clean, 11/2240224 files, 70327/4476416 blocks
4. ตรวจสอบ file system ด้วยการ force run
ใช้ option -f ในการตรวจสอบถึงแม้ว่าจะ clean แล้ว
$ fsck /dev/sda6
fsck from util-linux 2.20.1
e2fsck 1.42 (29-Nov-2011)
/dev/sda6: clean, 95/2240224 files, 3793503/4476416 blocks
$ fsck /dev/sda6 -f
fsck from util-linux 2.20.1
e2fsck 1.42 (29-Nov-2011)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/sda6: 95/2240224 files (7.4% non-contiguous), 3793503/4476416 blocks
5. แก้ไขปัญหาหลังจากตรวจสอบแล้ว
ใช้ option -y
$ fsck -y /dev/sda6
fsck from util-linux 2.20.1
e2fsck 1.42 (29-Nov-2011)
/dev/sda6 contains a file system with errors, check forced.
Pass 1: Checking inodes, blocks, and sizes
Inode 2060353 is a unknown file type with mode 0137642 but it looks
like it is really a directory.
Fix? yes
Pass 2: Checking directory structure
Entry 'test' in / (2) has deleted/unused inode 49059. Clear? yes
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/sda6: ***** FILE SYSTEM WAS MODIFIED *****
/dev/sda6: 96/2240224 files (7.3% non-contiguous), 3793508/4476416 blocks
โครงสร้างคำสั่ง
fsck [-lsAVRTMNP] [-r [fd]] [-C [fd]] [-t fstype] [filesystem...] [--] [fs-specific-options]
รายละเอียด
เป็นคำสั่งที่ใช้ตรวจสอบและซ่อมแซม file system ทำงานตั้งแต่เริ่ม boot เครื่อง ซึ่งถ้ามีสิ่งผิดปกติเกิดขึ้นจะเข้าสู่ consistent state ซึ่งทางผู้ดูแลสามารถใช้คำสั่ง fsck เพื่อแก้ไขปัญหาได้ เนื่องจากเป็นคำสั่งที่อันตรายเนื่องจากเกี่ยวข้องกับ file system จึงจำเป็นต้องใช้ user ในระดับ root หรือ super user ในการทำงาน
Option
-l Create an exclusive flock(2) lock file (/run/fsck/<diskname>.lock) for whole-disk device. This option can be used with one device only (this means that -A and -l are mutu‐ ally exclusive). This option is recommended when more fsck(8) instances are executed in the same time. The option is ignored when used for multiple devices or for non- rotating disks. fsck does not lock underlying devices when executed to check stacked devices (e.g. MD or DM) – this feature is not implemented yet. -r [fd] Report certain statistics for each fsck when it completes. These statistics include the exit status, the maximum run set size (in kilobytes), the elapsed all-clock time and the user and system CPU time used by the fsck run. For example: /dev/sda1: status 0, rss 92828, real 4.002804, user 2.677592, sys 0.86186 GUI front-ends may specify a file descriptor fd, in which case the progress bar information will be sent to that file descriptor in a machine parseable format. For example: /dev/sda1 0 92828 4.002804 2.677592 0.86186 -s Serialize fsck operations. This is a good idea if you are checking multiple filesystems and the checkers are in an interactive mode. (Note: e2fsck(8) runs in an interac‐ tive mode by default. To make e2fsck(8) run in a non-interactive mode, you must either specify the -p or -a option, if you wish for errors to be corrected automatically, or the -n option if you do not.) -t fslist Specifies the type(s) of filesystem to be checked. When the -A flag is specified, only filesystems that match fslist are checked. The fslist parameter is a comma-separated list of filesystems and options specifiers. All of the filesystems in this comma-separated list may be prefixed by a negation operator 'no' or '!', which requests that only those filesystems not listed in fslist will be checked. If none of the filesystems in fslist is prefixed by a negation operator, then only those listed filesystems will be checked. Options specifiers may be included in the comma-separated fslist. They must have the format opts=fs-option. If an options specifier is present, then only filesystems which contain fs-option in their mount options field of /etc/fstab will be checked. If the options specifier is prefixed by a negation operator, then only those filesystems that do not have fs-option in their mount options field of /etc/fstab will be checked. For example, if opts=ro appears in fslist, then only filesystems listed in /etc/fstab with the ro option will be checked. For compatibility with Mandrake distributions whose boot scripts depend upon an unauthorized UI change to the fsck program, if a filesystem type of loop is found in fslist, it is treated as if opts=loop were specified as an argument to the -t option. Normally, the filesystem type is deduced by searching for filesys in the /etc/fstab file and using the corresponding entry. If the type can not be deduced, and there is only a single filesystem given as an argument to the -t option, fsck will use the specified filesystem type. If this type is not available, then the default filesystem type (currently ext2) is used. -A Walk through the /etc/fstab file and try to check all filesystems in one run. This option is typically used from the /etc/rc system initialization file, instead of multiple commands for checking a single filesystem. The root filesystem will be checked first unless the -P option is specified (see below). After that, filesystems will be checked in the order specified by the fs_passno (the sixth) field in the /etc/fstab file. Filesystems with a fs_passno value of 0 are skipped and are not checked at all. Filesystems with a fs_passno value of greater than zero will be checked in order, with filesystems with the lowest fs_passno number being checked first. If there are multiple filesystems with the same pass number, fsck will attempt to check them in parallel, although it will avoid running multiple filesystem checks on the same physical disk. fsck does not check stacked devices (RAIDs, dm-crypt, ...) in parallel with any other device. See below for FSCK_FORCE_ALL_PARALLEL setting. The /sys filesystem is used to detemine dependencies between devices. Hence, a very common configuration in /etc/fstab files is to set the root filesystem to have a fs_passno value of 1 and to set all other filesystems to have a fs_passno value of 2. This will allow fsck to automatically run filesystem checkers in parallel if it is advantageous to do so. System administrators might choose not to use this configuration if they need to avoid multiple filesystem checks running in parallel for some reason – for example, if the machine in question is short on memory so that excessive paging is a concern. fsck normally does not check whether the device actually exists before calling a filesystem specific checker. Therefore non-existing devices may cause the system to enter filesystem repair mode during boot if the filesystem specific checker returns a fatal error. The /etc/fstab mount option nofail may be used to have fsck skip non-existing devices. fsck also skips non-existing devices that have the special filesystem type auto. -C [fd] Display completion/progress bars for those filesystem checkers (currently only for ext[234]) which support them. fsck will manage the filesystem checkers so that only one of them will display a progress bar at a time. GUI front-ends may specify a file descriptor fd, in which case the progress bar information will be sent to that file descriptor. -M Do not check mounted filesystems and return an exit code of 0 for mounted filesystems. -N Don't execute, just show what would be done. -P When the -A flag is set, check the root filesystem in parallel with the other filesystems. This is not the safest thing in the world to do, since if the root filesystem is in doubt things like the e2fsck(8) executable might be corrupted! This option is mainly provided for those sysadmins who don't want to repartition the root filesystem to be small and compact (which is really the right solution). -R When checking all filesystems with the -A flag, skip the root filesystem. (This is useful in case the root filesystem has already been mounted read-write.) -T Don't show the title on startup. -V Produce verbose output, including all filesystem-specific commands that are executed. fs-specific-options Options which are not understood by fsck are passed to the filesystem-specific checker. These options must not take arguments, as there is no way for fsck to be able to properly guess which options take arguments and which don't. Options and arguments which follow the -- are treated as filesystem-specific options to be passed to the filesystem-specific checker. Please note that fsck is not designed to pass arbitrarily complicated options to filesystem-specific checkers. If you're doing something complicated, please just execute the filesystem-specific checker directly. If you pass fsck some horribly complicated options and arguments, and it doesn't do what you expect, don't bother reporting it as a bug. You're almost certainly doing something that you shouldn't be doing with fsck. 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 filesystem checkers: -a Automatically repair the filesystem without any questions (use this option with caution). Note that e2fsck(8) supports -a for backward compatibility only. This option is mapped to e2fsck's -p option which is safe to use, unlike the -a option that some filesystem checkers support. -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. -r Interactively repair the filesystem (ask for confirmations). Note: It is generally a bad idea to use this option if multiple fsck's are being run in parallel. Also note that this is e2fsck's default behavior; it supports this option for backward compatibility reasons only. -y For some filesystem-specific checkers, the -y option will cause the fs-specific fsck to always attempt to fix any detected filesystem corruption automatically. Sometimes an expert may be able to do better driving the fsck manually. Note that not all filesystem-specific checkers implement this option. In particular fsck.minix(8) and fsck.cramfs(8) do not support the -y option as of this writing.
กลุ่มคำสั่ง
fstab(5), mkfs(8), fsck.ext2(8) or fsck.ext3(8) or e2fsck(8), cramfsck(8), fsck.minix(8), fsck.msdos(8), fsck.jfs(8), fsck.nfs(8), fsck.vfat(8), fsck.xfs(8), reiserfsck(8).
Reference:
Author: Suphakit Annoppornchai
Credit: https://saixiii.com
