AVStool uses Perl's signal handling functions to catch interrupt and quit signals. Perl, however, has an unusual syntax for denoting variables, arrays, user functions, and built-in functions. Variable substitution does not occur within single quotes. Array subscripting starts with 0 by default. An entire array is assigned by enclosing the array elements in parenthesis with each element separated by a comma.
Associative arrays are arrays that are indexed by strings.
The index string is known as the key and the datum associated with a key is called the value. Associative arrays may be assigned in a manner similar to arrays except that the elements are given as pairs of keys and values. One unusual data structure of Perl is the list. Lists are enclosed by parentheses and their elements are separated by commas. Lists are often used to access the arguments of subroutines and to assign scalar variables from the elements of an array.