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+====== Command line expansion =====
+When you type a command the shell does a few things before executing the command.  Before we get to that we need a new command, called ''echo'' which simply prints its output to standard output:
+<code bash>
+$ echo this is a test
+this is a test
+</code>
+Now here's an interesting example that might get you scratching your heads:
+<code bash>
+$ echo *
+copy_of_file.txt my_file.txt my_file2.txt subdirectory
+</code>
+To understand what happened here, recall that ''*'' is a wildcard that will match any character, and so before applying the echo command, the wildcard was expanded to match any file name in your current directory.

NSCI 580A3 fall 2017