Linux virtualization with Qemu

Linux virtualization with Qemu
For virtualization in Linux , you have easy and powerful way!
Install Qemu:

sudo apt-get install qemu

(in other distributions that name is qemu too)

After installing Qemu , open your terminal and try it:

For making img file :

qemu-img create win7.img 10G

qemu-img create centos.img 10G

For booting and installing your OS in img file via cdrom:

qemu --boot c -cdrom /dev/cdrom -hda win7.img -user-net -m 256

For booting and installing your OS in img file via iso file:

qemu-system-x64 -boot d -cdrom /path/to/win7.iso -hda win7.img -user-net -m 256

Description:
-m : refer to memory usage
-user-net : enabling network
qemu-system-x64 : for 64 bit systems

Note : If you wanna install 64 bit system , you should do it via qemu-system-x64. and for 32 bit system , do it : qemu-system-i386
Note: in some distribution qemu-system-x64 is qemu-system-x86_64
Note : with "qemu" command you can install your OS . but it's better that you call the special commands.