local variable
A variable that is present within the current instance of the shell. It is not available to programs that are started by the shell.

loop
Enables you to execute a series of commands multiple times. Two main types of loops are the while and for loops.

ls
The command used to list the files in a directory.

main code
Consists of all the commands in a shell script that are not contained within functions.

major number
UNIX uses this to associate a block special file or a character special file with a device driver.

man page
Every version of UNIX comes with an extensive collection of online help pages called man pages (short for manual pages). The man pages are the authoritative source about your UNIX system. They contain complete information about both the kernel and all the utilities.

metacharacter
In a regular expressions, a metacharacter is a special character that is expanded to match patterns.