An Operating Systems Vade Mecum

Exercises 2556 EXERCISES1. Describe the features available in a command language with which you are familiar.What features described in this chapter are not available? Are these omissionsdue to design outside the command interpreter, or could they be added? Forthose that could be added, suggest a syntax. For those that cannot be added,explain why.2. In what way are the commands one might give an interactive file manager similarto the commands one might give a text editor? In what way are they different?3. If the operating system does not provide for any inter-process data transfer, howcan the command interpreter establish a pipeline that directs the output of one processinto the input of another?4. How do pipelines of processes and the ability for processes to start subordinateprocesses interfere with each other?5. Find out what computer networks are accessible to your computer. What is theform of a mail address on these networks?6. A message sent to someone’s terminal can be a nuisance to the recipient. Designsome mechanism to allow users to restrict incoming messages.7. It was recently discovered that the ability to send arbitrary messages to someone’sterminal can introduce security problems. The problem arises because a debuggingfeature of the terminal allows it to enter a mode in which it echoes all data comingfrom the computer back to the computer. How do the two features, messages andterminal debugging, combine to create a problem?8. Some operating systems allow programs to load the terminal input buffer withcharacters as if the user had typed them in. These characters are then displayed;the user can modify them and activate the line. When would such a facility be useful?When would it be harmful?