CSCI 243 Midterm Exam

Fall 2007

Instructions: Write your name in the space provided at the top of the page and answer the questions below. This exam is closed book, closed notes, closed neighbor, closed internet, open (hopefully!) minds. Be complete but concise in your answers and write legibly—if I can’t decipher it, then it’s wrong! Write your answers in the space provided. If you need more room, write them on the back of one of the test pages and leave a note so I’ll know where to find it. Read through the entire exam before starting to answer any questions in order to plan your strategy to maximize your score. There are 100 points on the exam, not counting bonuses, and each question is worth 3 points. You have 50 minutes to complete it. Good luck and have fun!

I. UNIX COMMANDS

a. Write a Unix command to list all the files in the current directory, including those whose names begin with a period.

b. Write a Unix command that renames the file foo to bar (both in the current directory).

c. Write a Unix command to list all the processes being run by user don.

d. Write a Unix command to change the permissions on file foo in the current directory to allow read and write access by the owner, read access by other group members, and no access to anyone else.

e. Write a Unix command to force a program to end whose process ID is 15482 and whose parent process ID is 13021.

f. Write a Unix command that creates an empty file named foo with a time stamp of the current date and time.

g. Write a Unix command that compares two files, foo and bar, and prints the differences as a series of change commands.

h. What Unix command allows you to change your password?

i. Write a Unix command to find all occurrences of the string Linux in files foo and bar.

j. Write a Unix command to list all files in the current directory that start with a lower case a.

k. What Unix command allows a program to continue running after you have logged off?

l. What Unix command lists a file a page at a time, pausing between pages?

m. What Unix command displays and allows you to set the date and time?

n. What Unix command copies the file foo from the current directory to the parent of the current directory?

o. If the current directory is not in your path, what Unix command runs the program foo which is in the current directory?

p. What command displays the number of letters, words, and lines in file bar?

q. What command lists all the current users who are logged in?

r. What command runs the program foo in the background, allowing you to do other tasks in the shell window concurrently?

s. What command recursively removes all files and subdirectories (except those starting with a period) from the current directory?

t. What command displays the contents of a file as hex values, characters, octal values, etc?

II. UNIX COMMAND SEQUENCES

a. What command or sequence of commands eliminates duplicate lines in a file? You may rearrange the lines of the file as needed.

b. What command sequence creates a file if necessary, and enters the text you type in the file, all without using a text editor?

c. What do you type in vi to replace every occurrence of the word foo with the word bar?

d. What would you type to run the program foo and capture the output to the file bar?

e. What command sequence runs the program foo and the program bar, and uses the output of the program foo as input to the program bar?

III. MISCELLANEOUS QUESTIONS

a. What do you type in the input window to abort the program you are running?

b. What do you type to indicate end of input?

c. What character indicates the beginning of a line in a regular expression?

d. In lex, how do you specify white space?

e. What token does the regular expression [a-z_A-Z][a-z_A-Z0-9]* specify in lex?

f. How are the three parts of a lex file separated?

g. What key sequence inserts text at the end of the current line in vi?

h. What are the three I/O streams that any running program has?

i. In what programming language is most of the Unix operating system written?

j. Who is the creator (and maintainer of the kernel) of the Linux operating system?