kernel
 

if we install a new kernel in our linux system, will older one remove automatically or it'll be there with new one or the newer one'll upgrade the older???

if installation of new kernel will remove the older then what about that particular very short time when there is no kernel in the system....... i mean time between older one is removed and newer is ready to install.....

i knw this is very clumpsy question, but i tried best to explain u my problem.

You might be confusing the kernel with kernel modules, but after boot the kernel resides in memory, meaning you can replace or upgrade your kernel on-disk safely. If you are installing a new kernel during an update, it will replace the primary one on disk with a new kernel, and keep the old one in case there are problems. You aren't actually using the new kernel until you reboot.