Review

Know the Concepts

• Describe the lifecycle of a file descriptor.

• What are the standard file descriptors and what are they used for?

• What is a buffer?

• What is the difference between the .data section and the .bss section?

• What are the system calls related to reading and writing files?

Use the Concepts

• Modify the toupper program so that it reads from STDIN and writes to STDOUT instead of using the files on the command-line.

• Change the size of the buffer.

• Rewrite the program so that it uses storage in the .bss section rather than the stack to store the file descriptors.

• Write a program that will create a file called heynow.txt and write the words "Hey diddle diddle!" into it.

Going Further

• What difference does the size of the buffer make?

• What error results can be returned by each of these system calls?

• Make the program able to either operate on command-line arguments or use STDIN or STDOUT based on the number of command-line arguments specified by ARGC.

• Modify the program so that it checks the results of each system call, and prints out an error message to STDOUT when it occurs.