To perform a file system check, please proceed as follows:

1. Determine which hard disk is to be checked.
   
   fdisk -l
Disk /dev/sda: 15 heads, 57 sectors, 790 cylinders
Units = cylinders of 855 * 512 bytes
Device Boot Begin Start End Blocks Id System
/dev/sda1 1 1 24 10231+ 82 Linux swap
/dev/sda2 25 25 48 10260 83 Linux native

   IMPORTANT !!!
   The hard disk must not be mounted!
   
   
2. Execute the filesystem check via the command fsck -y /dev/<device>.
   Checking the swap partition is not possible via fsck and is usually unnecessary. To check the 2nd partition enter the command:
   
   fsck -y /dev/sda2