how to change automatic boot order, if i have dual boot kali and debian installed on pc. i want to boot debian automatically, but kali is booting automatically as i have installed kali after debian installation.
Even with dual-boot, your machine is only booting one OS at a time. So have two OSes doesn't increase boot time at all. Now, if you are booting one of those OSes in a VM, that changes things but still not the initial boot time.
With respect John, I think you are misreading what the OP is after.
Raman do you think you will want to boot Debian each time, for the long term? Or do you think that you may want to simply boot to the Distro that you were last working on, to continue work there?
Either option can simply involve making small changes to a file called
with a Text Editor, run as Root or using sudo.
If you want to have Debian back on top of your Grub Menu, and booting into that automatically, then it involves some simple steps at startup, using the Advanced Options in your Grub Menu, and we can put Debian back on top and as the default.
Another option that is available is to use a utility by Daniel Richter called Grub Customizer, which is OK with 2 Linux, but if you ever install more it can be very slow and tedious, and can be difficult to remove.
Yet another option is to install Timeshift on each of Debian and Kali (which I recommend as a matter of course anyway), and then use Timeshift to take a snapshot of both, and restore Debian.