outlet - an opening that permits escape or release; he blocked the way out; the canyon had only one issue. exit, way out, issue. opening - a vacant or unobstructed space that is man-made; they left a small opening for the cat at the bottom of the door.
Differences between grep, pgrep, egrep, and fgrep (Linux): grep grep is an acronym that stands for Global Regular Expressions Print. grep is a program which scans a specified file or files line by line, returning lines that contain a pattern. A pattern is an expression that specifies a set of strings by interpreting characters as meta-characters.
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.