Chapter 12 in your Unix textbook has a program that reverses strings (p389). Implement it, that is, type the program (or get it from the book's website), compile it, and run it a few times with different input. Make sure to retain the comments indicating where it came from.
Chapter 12 in your textbook also tells you how to prepare reusable functions. You will need to create reverse.c, reverse.h and a main function (e.g. main1.c) separately. (Note that there is a program called "reverse.c" in your C book, too, but that is a completely different program.) When you create the files, modify the program to prompt users to input words to be reversed. Then compile and link the files into an executable file (give it a name e.g main1). Use ls -l to print the information of it in your script. Then run it a few times with different inputs to make sure it works. In this part, make sure that you use -c and that the .o files are created.
In this part, you will need to create a make file and create the interdependencies related to your executable file (e.g. "main1"). First, remove all of the object modules and the executable files that you created before. Use ls to show that they are removed. Next, run the make command on your Makefile to re-create the object modules and executable file. Use ls to verify that the files are created. Then run the new executable files a few times with different inputs to make sure it works the same as before.