<Ul> <Li> By pressing e, it is possible to edit parameters for the selected operating system before the operating system is started . Typically, this is used to change kernel parameters for a Linux system . The reason for doing this in GRUB (i.e. not editing the parameters in an already booted system) can be an emergency case: the system has failed to boot . Using the kernel parameters line it is possible, among other things, to specify a module to be disabled (blacklisted) for the kernel . This could be required if the specific kernel module is broken and thus prevents boot - up . For example, to blacklist the kernel module nvidia - current, one could append modprobe. blacklist = nvidia - current at the end of the kernel parameters . </Li> <Li> By pressing c, the user enters the GRUB command line . The GRUB command line is not a regular Linux shell, like e.g. bash, and accepts only certain GRUB - specific commands, documented by various Linux distributions . </Li> </Ul> <Li> By pressing e, it is possible to edit parameters for the selected operating system before the operating system is started . Typically, this is used to change kernel parameters for a Linux system . The reason for doing this in GRUB (i.e. not editing the parameters in an already booted system) can be an emergency case: the system has failed to boot . Using the kernel parameters line it is possible, among other things, to specify a module to be disabled (blacklisted) for the kernel . This could be required if the specific kernel module is broken and thus prevents boot - up . For example, to blacklist the kernel module nvidia - current, one could append modprobe. blacklist = nvidia - current at the end of the kernel parameters . </Li> <Li> By pressing c, the user enters the GRUB command line . The GRUB command line is not a regular Linux shell, like e.g. bash, and accepts only certain GRUB - specific commands, documented by various Linux distributions . </Li> <P> Once boot options have been selected, GRUB loads the selected kernel into memory and passes control to the kernel . Alternatively, GRUB can pass control of the boot process to another boot loader, using chain loading . This is the method used to load operating systems such as Microsoft Windows, that do not support the Multiboot Specification or are not supported directly by GRUB . </P>

What is the function of grub in linux