A tutorial on Fsck Command in Linux for file system repair

fsck (File system check) Is a command-line utility that allows you to perform consistency checks and interactive fixes on one or more Linux file systems. Fsck uses its own program for each type of system file it checks.

You can use commands fsck For repairing corrupted system files in cases where the system fails to boot, or the partition cannot be loaded or read.

In this article we will talk about commands fsck With usage examples.

How to use the fsck

Command fsck It takes the following general form

fsck [OPTIONS] [FILESYSTEM]

Only root or user with rights sudo Which can clear the buffer.

When there is no FILESYSTEM As an argument, fsck It will check the devices registered in the file fstab.

Never run fsck On the attached section (Vehicle) Because it can corrupt system files. Before trying to scan or repair system files, always use the command unmount Before using the fsck tool.

Command fsck It is a versatile tool for many Linux system file scanners (fsck.*) And accept different options depending on the type of file system.

Check out the guy pages for more information on the specific checkers game. For example, to see the options available for fsck.ext4, Type:

man fsck.ext4

How to repair corrupted system files

The fsck command is the simplest use case for repairing system files ext3 or ext4 Damaged.

  1. If you do not know the name of the device, use it fdisk, dfOr, another tool to find it.
  2. Unmount the device to be scanned:
    sudo umount /dev/sdc1
    
  3. Run the commandfsck To repair a file system:
    sudo fsck -p /dev/sdc1
    

    Selection -p I tell you fsck To automatically fix problems that can be fixed safely without user intervention.

  4. After repairing the file system, install the partition with the following command:
    sudo mount /dev/sdc1
    

How to fix a root file system

fsck The root system files could not be checked on a running device because they cannot be dismounted.

If you want to scan or repair root system files, you have several options. You can manage fsck To boot at boot up, boot the system into recovery mode or use a live CD.

How do you run fsck In recovery mode:

  1. Enter the boot menu and select Advanced options
  2. Select recovery mode thenfsck“.
  3. When prompted to re-mount the root file system, selectYes“.
  4. Once done, proceed with the normal boot.

escape from fsck From direct CD:

  1. Play live CD.
  2. use fdisk or parted Find the name of the root partition.
  3. Open a terminal and run:
    sudo fsck -p /dev/sda1
  4. Once done, restart your system and boot up.

How to check file systems during operation

On most Linux distributions, fsck It will run at boot time if marked “dirty” on system files or after a specified number of boot processes or time.

To find out the current download number, check the frequency number, check the interval, the last scan time for a particular section, use the tooltune2fs:

sudo tune2fs -l /dev/sdc1 | grep -i 'last checked|mount count'
Mount count:              292
Maximum mount count:      -1
Last checked:             Tue Jul 24 11:10:07 2018
Check interval:           0 (<none>)
  • “Maximum mount count” is the number of downloads after which the file system will be scanned. Score 0 or -1 Which means fsck will never work.
  • The “verification interval” is the maximum time between two file system scans.

If you want to run, for example fsck After every 25 shoes, write:

sudo tune2fs -c 25 /dev/sdc1

You can also set the maximum time between two tests. For example, to set it to 1 month, run the following command:

sudo tune2fs -i 1m /dev/sdc1

Determination fsck Boot Up On Boot into SystemD Distribution Use the following parameters in kernel boot:

fsck.mode=force
fsck.repair=yes

In old Linux distributions, fsck It will run at boot if /forcefsck exist:

sudo touch /forcefsck

Internal option fstab

fstab A configuration file that tells the system how and where to install partitions.

Files /etc/fstab It contains the list of entries as follows:

sudo nano /etc/fstab
# [File System] [Mount Point] [File System Type] [Options] [Dump] [PASS]
/dev/sda1       /             ext4               defaults  0      1
/dev/sda2       /home         ext4               defaults  0      2
server:/dir     /media/nfs    nfs                defaults  0      0

Last sixth column ([PASS]) Is an option that controls the order in which system files are scanned upon restart.

  • 0 – Don’t check.
  • 1 – The file system is checked first one by one.
  • 2 All other system files are scanned later and (maybe) in parallel.

All root filesystems must have a value 1, And any other system files you want to check should have value 2

Conclusion

fsck It is a command-line tool to optionally check and repair Linux file systems.

Learn more about orders fsck, Visit the fsck man page or type man fsck At your stop.

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