MyLinuxNote4

dd if=/dev/zero of=filename bs=1024 count=2 [ This will create a 2MB file.]

iptables -A INPUT -S 192.168.1.50 -p icmp -j DROP

echo "Hello root" | mail -v -s hello root@server1

cat bootdisk.img > /dev/fd0

dd if=bootdisk.img of=/dev/fd0

raid 0 -> striping.
raid 1 -> mirroring.
raid 5 -> striping with parity.


Different TTY output at the time of redhat linux installation:

alt-f1 -> the installer program in text mode
alt-f2 -> a bash shell
alt-f3 -> a log of installer messages
alt-f4 -> a log of kernel messages
alt-f5 -> stdout from mke2fs and grub command
alt-f7 -> The installer program in graphical mode