Example 4-5 Automation using external bash variables

• Here we would like to modify bash script for Example 4-5 so it can take the range of years for the three structure as command line input. There are two possibility for this. In the first method, we give the beginning and ending years as arguments to our bash program. This version is done in script insn_tree_1.bash.

• In the second method, we use command read to interactively get the beginning and end years from user. This method is done in script insn_tree_2.bash