1) File system must be unmounted, you cannot repair it while it is running. Take system down to runlevel one (make sure you run all command as root user):
# init 1
2)Unmount file system, for example if it is /home (/dev/sda3) file system then type command:
# umount /home
OR
# umount /dev/sda3
3) Now run fsck on the partition:
# fsck /dev/sda3
However be sure to specify the file system type using -t option. Otherwise, Result would be more corruption as fsck by default assumes ext2 …

If you are using Red Hat Linux then use up2date command to install most common modules:
# up2date module-name
Use following command to list all supported modules:
# up2date –showall | grep -i ‘perl’
OR use yum command under CentOS/RHEL 5/Fedora core:
# yum list available ‘perl’
If you are using Debian Linux, try to use apt-get command to install common perl module. However following is the recommended way to install a perl module.
A) Start CPAN Shell:
# perl -MCPAN -e shell
B) Install a perl module:
At cpan> …

Maintaining yum
The yum system does not require any routine maintenance. To ensure that yum operations are carried out at optimal speed, disable or remove repository definitions which you no longer require. You may also clear the files from the yum caches in order to recover disk space.
 
 
Disabling or …

Focus of this Article
This Linux Security HOWTO is intended for a technical audience, Linux system administrators, and security people in corporations and organizations that have to use commercial Linux distributions for their production environment. If you are a Linux expert then you may find familiar material here, but you will have difficulties to find documentation on various topics like restricting su access to system and shared accounts only as covered in this article, see Restricting su Access to System and …