cp
The command used to copy files.

daemon
A system-related background process that often runs with the permissions of root and services requests from other processes.

debugging hook
A function or set of commands that executes only when a shell script executes with a special argument. Debugging hooks provide a convenient method for tracing the execution of a script in order to fix problems.

default behavior
The output that is generated when a command runs as a simple command is called the default behavior of that command.

directory
A type of file used to store other files. For users familiar with Windows or Mac OS, UNIX directories are equivalent to folders.

directory tree
UNIX uses a hierarchical structure for organizing files and directories. This structure is often referred to as a directory tree. The tree has a single root node, the slash character (/), and all other directories are contained below it.

environment variable
A variable that is available to any program that is started by the shell.

escape sequence
A special sequence of characters that represents another character.