How to Force a Filesystem Check on a Linux Root Partition (fsck)

Root Filesystem

In this example the /dev/sda1 partition is mounted as the root filesystem ( /).

# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda1              63G   41G   19G  69% /

Running fsck /dev/sda1 on a mounted root filesystem produces an error because the device is in use.

# fsck /dev/sda1
fsck from util-linux-ng 2.17.2
e2fsck 1.41.12 (17-May-2010)
/dev/sda1 is mounted.
e2fsck: Cannot continue, aborting.

For non‑root filesystems you can simply unmount the partition and run fsck, but the root filesystem requires a different approach.

Tune2fs Output Before Reboot

Before forcing a check, examine when the root filesystem was last checked using tune2fs and grep for the word “check”.

# tune2fs -l /dev/sda1 | grep -i check
Last checked:             Mon Nov 24 12:39:44 2015
Check interval:           15552000 (6 months)
Next check after:         Sun May 22 13:39:44 2016

Last checked – the timestamp of the most recent fsck on the root filesystem.

Check interval – how often the filesystem is scheduled for a check (here, every six months).

Next check after – the future date when the next automatic check will occur.

We want to run a check immediately rather than waiting until May.

Create /forcefsck File to Force Check

To force a check on the next reboot, create an empty file named forcefsck in the root directory.

# cd /
# touch forcefsck
# ls -l /forcefsck
-rw-r--r-- 1 root root 0 Mar 9 20:15 /forcefsck

Then reboot the system.

# reboot

Tune2fs Output After Reboot

After the reboot, the system runs fsck on the root filesystem and automatically removes the /forcefsck file.

# ls -l /forcefsck
ls: cannot access /forcefsck: No such file or directory

Running tune2fs again shows the updated timestamps.

# tune2fs -l /dev/sda1 | grep -i check
Last checked:             Wed Mar 09 20:30:04 2016
Check interval:           15552000 (6 months)
Next check after:         Mon Sep 05 21:30:04 2016

The “Last checked” field now reflects the recent reboot, confirming that the forced filesystem check was performed.