On debain you have by default three programs to maintain your installed software packages:
dselect : a curses based frontend to the other programs
dpkg : maintain software, like installing packages, purging , updateing etc.
apt-get: to install software directly from the media or the net and to maintain it

# Permission
7 full
6 read and write
5 read and execute
4 read only
3 write and execute
2 write
1 execute
0 none
In the command, the first number refers to your permissions, the second refers to group, and the third refers to general users. Typing the command:
chmod 751 filename
gives you full access, the group read and execute, and all others execute only permission

df -ah | grep -e [8-9][0-9]% -h - to check drives usage that are in the range of 80 to 99 percent capacity

Using modules
Perl comes with some internal modules. There are also two other resources for finding Perl modules: Debian and CPAN. CPAN is the Comprehensive Perl Archive Network; one of its primary functions is to serve as a repository of Perl modules.

Linux IDE naming conventions:
/dev/hda 1st (Primary) IDE controller Master
/dev/hdb 1st (Primary) IDE controller Slave
/dev/hdc 2nd (Secondary) IDE controller Master
/dev/hdd 2nd (Secondary) IDE controller Slave
SCSI disks are labeled /dev/sda, /dev/sdb, /dev/sdc etc... to represent the first, second, third
SCSI hard drive partitions are represented by an additional number. i.e. First drive first partition, /dev/sda1, second partition, /dev/sda2,...

date -s "12 MAR 2008 16:07:00" - to set date