If the memory is very full (on Linux), you may execute the following command:

sync; echo 3 > /proc/sys/vm/drop_caches

All the caches are cleared now. Your system may respond a bit slower now, while the caches are being refilled.

To start a ‘fsck’ (for Windows users: a ‘checkdisk’ for Linux), you may execute the following command in your shell:

touch /forcefsck

fsck will run at next boot.

This command creates a file called ‘forcefsck’ in the root folder (‘/’). At boot time, fsck checks whether this file exists. When it does, fsck checks the harddisk.