Suppose a UNIX a system has been set up so that each student and the instructor have their own ID and all are in the same group (with no other users). The files used by the course are on a timesharing system used by other courses.

a. What permissions should a student have on a file that contains a homework solution?

b. What permissions should the instructo9r have on a file that contains course grades?

c. What permissions should be assigned to file (owned by the instructor) that is readable and writable by the instructor, executable by a student in the course, and inaccessible to any other student?

d. Suppose the instructor wants a directory in which each student can write a solution file, but only the instructor can read the files. What permission should the directory have?