ECS 30
Practice Midterm
The questions in this document may have appeared in midterms in previous years when
this class was taught by different instructors.
1. UNIX commands
a. (10 points) You just printed something to printer hexus, and find that it's printing a
bunch of garbage. What are the steps you take to cancel the print job?
b. (5 points) What UNIX command would you type to see a list of all of the files (including
the hidden files) in directory hw1?
c. (5 points) You just wrote and saved the file test2.c. Now you want to make sure that
only you can read and write it. What UNIX command would you type to make test.c
only readable and writeable by you?
d. (5 points) You want to move all of your C source files (ending in .c) and header files
(ending in .h) from your hw1 subdirectory to your mid1 subdirectory. What UNIX
command should you type?
e. (5 points) You want to view the file test3.c a screen at a time. What UNIX
command would you type?
2. (50 points) Write a complete, warning-free, C program that lists all of the common
factors of two positive integers. The program will prompt the user for the two
numbers, and then list on one line all the factors that the numbers have in
common. A factor of a number divides into that number with a remainder of zero.
The program will continue to ask the user for more pairs of numbers until the first
number entered is zero. Your prompts and formats should match that shown.
User input is in bold.
Please enter two positive integers: 20 12
1 2 4
Please enter two positive integers: 60 120
1 2 3 4 5 6 10 12 15 20 30 60
Please enter two positive integers: 8 9
1
Please enter two positive integers: 0 230
Done.
