In this article, we are going to review the fsck utility and its usage to help you repair disk errors.<\/p>\n
When to Use fsck in Linux<\/h4>\n
There are different scenarios when you will want to run fsck. Here are few examples:<\/p>\n
- \n
- The system fails to boot.<\/li>\n
- Files on the system become corrupt (often you may see input\/output error).<\/li>\n
- Attached drive (including flash drives\/SD cards) is not working as expected.<\/li>\n<\/ul>\n
fsck Available options<\/h4>\n
Fsck command needs to be run with superuser privileges or\u00a0root<\/strong>. You can use it with different arguments. Their usage depend on your specific case. Below you will see some of the more important options:<\/p>\n
- \n
- \n
- \n
-A<\/code>\u00a0\u2013 Used for checking all filesystems. The list is taken from\u00a0\/etc\/fstab<\/code>.<\/li>\n-C<\/code>\u00a0\u2013 Show progress bar.<\/li>\n-l<\/code>\u00a0\u2013 Locks the device to guarantee no other program will try to use the partition during the check.<\/li>\n-M<\/code>\u00a0\u2013 Do not check mounted filesystems.<\/li>\n-N<\/code>\u00a0\u2013 Only show what would be done \u2013 no actual changes are made.<\/li>\n-P<\/code>\u00a0\u2013 If you want to check filesystems in parallel, including root.<\/li>\n-R<\/code>\u00a0\u2013 Do not check root filesystem. This is useful only with \u2018-A<\/code>\u2018.<\/li>\n-r<\/code>\u00a0\u2013 Provide statistics for each device that is being checked.<\/li>\n-T<\/code>\u00a0\u2013 Does not show the title.<\/li>\n-t<\/code>\u00a0\u2013 Exclusively specify the filesystem types to be checked. Types can be comma separated list.<\/li>\n-V<\/code>\u00a0\u2013 Provide description what is being done.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\nHow to Run fsck to Repair Linux File System Errors<\/h3>\n
In order to run\u00a0fsck<\/strong>, you will need to ensure that the partition you are going to check is not mounted. For the purpose of this article, I will use my second drive\u00a0
\/dev\/sdb<\/code>\u00a0mounted in\u00a0\/mnt<\/code>.<\/p>\nHere is what happens if I try to run\u00a0fsck<\/strong>\u00a0when the partition is mounted.<\/p>\n
# fsck \/dev\/sdb\r\n<\/pre>\n
![\"Run](\"https:\/\/www.tecmint.com\/wp-content\/uploads\/2018\/09\/Run-fsck-on-Mounted-Partition.png\")
<\/a><\/p>\nRun fsck on Mounted Partition<\/p>\n<\/div>\n
To avoid this unmount the partition using.<\/p>\n
# umount \/dev\/sdb\r\n<\/pre>\n
Then\u00a0fsck<\/strong>\u00a0can be safely ran with.<\/p>\n
# fsck \/dev\/sdb\r\n<\/pre>\n
![\"Run](\"https:\/\/www.tecmint.com\/wp-content\/uploads\/2018\/09\/Run-fsck-on-Linux-Partition.png\")
<\/a><\/p>\nRun fsck on Linux Partition<\/p>\n<\/div>\n
Understanding fsck exit codes<\/h4>\n
After running\u00a0fsck<\/strong>, it will return an exit code. These cods can be seen in fsck\u2019s manual by running:<\/p>\n
# man fsck<\/strong>\r\n\r\n0 No errors\r\n1 Filesystem errors corrected\r\n2 System should be rebooted\r\n4 Filesystem errors left uncorrected\r\n8 Operational error\r\n16 Usage or syntax error\r\n32 Checking canceled by user request\r\n128 Shared-library error \r\n<\/pre>\n
Repair Linux Filesystem Errors<\/h4>\n
Sometimes more than one error can be found on a filesystem. In such cases you may want\u00a0fsck<\/strong>\u00a0to automatically attempt to correct the errors. This can be done with:<\/p>\n
# fsck -y \/dev\/sdb\r\n<\/pre>\n
The\u00a0
-y<\/code>\u00a0flag, automatically\u00a0\u201cyes\u201d<\/code>\u00a0to any prompts from fsck to correct an error.<\/p>\nSimilarly, you can ran the same on all filesystems (without\u00a0root<\/strong>):<\/p>\n
$ fsck -AR -y \r\n<\/pre>\n
How to Run fsck on Linux Root Partition<\/h3>\n
In some cases, you may need to run\u00a0fsck<\/strong>\u00a0on the\u00a0root<\/strong>\u00a0partition of your system. Since you cannot run\u00a0fsck<\/strong>\u00a0while the partition is mounted, you can try one of these options:<\/p>\n
- \n
- Force fsck upon system boot<\/li>\n
- Run fsck in rescue mode<\/li>\n<\/ul>\n
We will review both situations.<\/p>\n
Force fsck Upon System Boot<\/h4>\n
This is relatively easy to complete, the only thing you need to do is create a file called\u00a0forcefsck<\/strong>\u00a0in the root partition of your system. Use the following command:<\/p>\n
# touch \/forcefsck\r\n<\/pre>\n
Then you can simply force or schedule a reboot of your system. During the next bootup, the\u00a0fsck<\/strong>\u00a0will be performed. If downtime is critical, it is recommended to plan this carefully, since if there are many used inodes on your system,\u00a0fsck<\/strong>\u00a0may take some extra time.<\/p>\n
After your system boots, check if the file still exists:<\/p>\n
# ls \/forcefsck\r\n<\/pre>\n
If it does, you may want to remove it in order to avoid\u00a0fsck<\/strong>\u00a0on every system boot.<\/p>\n
Run fsck in Rescue Mode<\/h4>\n
Running\u00a0fsck<\/strong>\u00a0in\u00a0rescue mode<\/strong>\u00a0requires few more steps. First prepare your system for\u00a0reboot<\/strong>. Stop any critical services like\u00a0MySQL\/MariaDB<\/strong>\u00a0etc and then type.<\/p>\n
# reboot\r\n<\/pre>\n
During the boot, hold down the\u00a0
shift<\/code>\u00a0key so that the grub menu is shown. Select the \u201cAdvanced options<\/strong>\u201d.<\/p>\n![\"Grub](\"https:\/\/www.tecmint.com\/wp-content\/uploads\/2018\/09\/Grub-Advance-Options.png\")
<\/a><\/p>\nGrub Advance Options<\/p>\n<\/div>\n
Then choose \u201cRecovery mode<\/strong>\u201d.<\/p>\n
![\"Select](\"https:\/\/www.tecmint.com\/wp-content\/uploads\/2018\/09\/Select-Linux-Recovery-Mode.png\")
<\/a><\/p>\nSelect Linux Recovery Mode<\/p>\n<\/div>\n
In the next menu select \u201cfsck<\/strong>\u201d.<\/p>\n
![\"Select](\"https:\/\/www.tecmint.com\/wp-content\/uploads\/2018\/09\/Select-fsck-Utility.png\")
<\/a><\/p>\nSelect fsck Utility<\/p>\n<\/div>\n
You will be asked if you wish to have your\u00a0
\/<\/code>\u00a0filesystem remounted. Select\u00a0\u201cyes\u201d<\/code>.<\/p>\n![\"Confirm](\"https:\/\/www.tecmint.com\/wp-content\/uploads\/2018\/09\/Confirm-Root-Filesystem.png\")
<\/a><\/p>\nConfirm Root Filesystem<\/p>\n<\/div>\n
You should see something similar to this.<\/p>\n
![\"Running](\"https:\/\/www.tecmint.com\/wp-content\/uploads\/2018\/09\/Running-fsck-Filesystem-Check.png\")
<\/a><\/p>\nRunning fsck Filesystem Check<\/p>\n<\/div>\n
You can then resume to normal boot, by selecting\u00a0\u201cResume\u201d<\/strong>.<\/p>\n
![\"Select](\"https:\/\/www.tecmint.com\/wp-content\/uploads\/2018\/09\/Select-Normal-Boot.png\")
<\/a><\/p>\nSelect Normal Boot<\/p>\n<\/div>\n
Conclusion<\/h5>\n
In this tutorial you learned how to use fsck and run consistency checks on different Linux filesystem.<\/p>\n
- \n