There are two other constructs we can use within our configuration files. They are #include and #exec.
The #include construct tells Asterisk to read in the contents of another configuration file, and act as though the contents were at this location in this configuration file. The syntax is #include filename, where filename is the name of the file you'd like to include. This construct is most often used to break a large configuration file into smaller pieces, so that it's more manageable.
The #exec takes this one step further. It allows you to execute an external program, and place the output of that program into the current configuration file. The syntax is #exec program, where program is the name of the program you'd like to execute.
Let's look at example of both constructs in action.