BASIC FSCK USAGE, MAN PAGES AND EXIT CODES

FSCK, otherwise known as Filesystem check for linux, is a program built into Linux operating systems that essentially takes the place of CHKDSK in Windows. While Linux rarely needs to run FSCK, it has become more or less standard at boot time on most SystemD powered Linux distributions. FSCK not only checks the bootability of your drive, it also tries to repair problems that prevent the said drive from booting. This can be orphaned inodes, bad journal files, issues with sectors and bad blocks. While many of these could prevent a drive or file system from booting anyway, FSCK is a good first step to ensure drive health and maintain a file system when problems may arise. Linux has great damage control and security already built in that users can easily access to gain more control of their distribution.

Running the command man fsck:

will return a lot of information on the command. It will return possible exit codes(more on that in a minute) and a short description of what the command does, as with all commands, most forums suggest you use the man pages first and foremost, then go to Google when you need more information. While the man page for fsck itself gives a lot of useful information, the mother program E2FSCK seems to give more info. A basic man of E2FSCK gives options that can be ran with the command FSCK to force and automatically repair whatever issues the command may find, even if the filesystem seems fine. You can also move bad blocks to latter parts of the drive, which is useful if you have an old drive on a server or desktop that isn’t dying yet, but is getting bad sectors or blocks. Man pages are there for almost any command, these are just two that I chose to explain today. Using the help flag gets you similar information or at least options.

Exit codes are often indicative of some problem with the program running initially, however, an exit code of 0 usually means that there were no errors. Every program runs with different types of output. Error codes usually ascend by number based on severity. For an example of such error codes, a list has been pulled from the manpage for fsck:

E2FSCK or FSCK can be ran from a live environment to get the filesystem health information from an installed Linux filesystem. It’s usually recommended that you run e2fsck from a live cd with sudo access to get an accurate read, using the -f option will force an unscheduled check of the filesystem while -p option will usually automatically fix anything that it finds. These options can usually be used together. For a complete list of available options, either type man E2FSCK from the same terminal window or type e2fsck –help. Usually, most modern systems running SystemD init system will run this program by default during boot time. This is usually only ran to check over fstab to ensure that everything is booted that is listed in that file in the order it is listed. This sometimes fixes issues too, but it can be a good idea to run the command manually every once in a while. To run FSCK manually without using a live environment and force FSCK to check the filesystem on boot, use the following command:

That’s it! This is a small thing that can help solve some basic boot issues in linux, it’s also something that I run each time I perform system maintenance on the linux pc. I also run the CHDSK option in Windows when I’m maintenancing one of those as well. I hope that this helps. Stay tuned for more things like this in the following days and weeks.