PS2 variable
A shell variable whose content is usually the > character. The contents of the PS2 variable is displayed by the shell as a secondary prompt that indicates the previous command was not complete and the current command line is a continuation of that command line.

pwd
The pwd command prints the absolute path of the current directory.

quoting
Literally, to enclose selected text within some type of quotation marks. When applied to shell commands, quoting means to disable shell interpretation of special characters by enclosing the character within single or double quotes or by escaping the character.

read permission
The read permission of a file or directory determines which users can view the contents of that file or directory.

regular expression
A string that can describe several sequences of characters.

regular file
The most common type of files you will encounter. These files store any kind of data. This data may be stored in plain text, an application-specific format, or a special binary format that the system can execute.

relative path
Relative pathnames let you access files and directories by specifying a path to that file or directory relative to your current directory.

remainder function
The remainder of a division operation, which is the amount that is left over and thus not evenly divisible.

reserved word
A nonquoted word that is used in grouping commands or selectively executing them, such as: if, then, else, elif, fi, case, esac, for, while, until, do, or done.