Heart failure (HF), often referred to as congestive heart failure (CHF), occurs when the heart is unable to pump sufficiently to maintain blood flow to meet the body's needs. The terms chronic heart failure (CHF) or congestive cardiac failure (CCF) are often used interchangeably with congestive heart failure.
GRUB Rescue Shell. GRUB Rescue offers a limited set of commands to help you configure a one-time normal boot and repair GRUB from your operating system. Just because GRUB doesn't load properly doesn't mean your operating system is unbootable; the Linux filesystem is usually still intact and in good condition.
GRUB is GRand Unified Bootloader, the default bootloader in Linux. GRUB can be used to boot Linux in single user mode. The single user mode is the restricted mode, that is used for maintenance purposes. In single user mode, the only user available is the root user, and in RHEL, no password is asked for login.