Name:

Full E-mail Address:

UNIX System Used:

1. Insert separating commas in a large integer number, so that "1000000"
becomes 1,000,000 and "10000" becomes 10,000.  To do this efficiently,
search and  replace several times by means of a while loop, making use
of the fact that a substitution instruction returns a true value if a
substitution actually took place.

2. The /etc/passwd file has a single line per user.  Each line consists
of 7 colon-delimited fields:
loginname:password:userid(UID):groupid(GID):username:directory:shell
   Copy /etc/passwd into your home directory with a suitable name.

(a) Write a program that reads each line from your password file.  Use
the split function to split the scalar containing a password entry into
an array with 7 entries.

(b) Create an array, each of whose elements is a reference to an array
consisting of the 7 fields from a password entry.  After the array is
fully loaded, print the entries from this array that corresponds to
YOUR login name and root.

(c) Make a copy of the program in part (b). Modify the copy to use
hashes, instead of arrays, for the password records (lines).  You
should generate an array of hashes.  Consider using the field names
(See at beginning of exercise) as the keys.  Create a function that
will return a list of the keywords.

(d) Make a copy of the program in part (c).  Modify the copy to use a
hash, instead of an array to hold the records (lines).  You should
generate a two-dimensional hash.  The loginname makes a good key for
this hash.  Create a print function that takes a single argument (a
loginname) and prints the loginname followed by the key/value pairs
from the corresponding record (line).

3.  Discuss the differences among the following:
(a) system ("ls")       (b) exec ("ls"  )               (c) `ls`

4. Write a script that formats the paragraphs of all files specified in
the command line in a left-justified manner.  The line length is to be a
maximum of 40 characters;  indentation is not required.  Read the entire
input stream into a string, replace all newlines not followed by
newlines with empty strings, and feed the result to Text::Wrap::wrap

5. Write a script to output the days of the current calendar week in the
format:
Mon     Tue     Wed     Thu      Fri    Sat     Sun
21      22      23      24       25     26      27
Use Date::Manip to find the date of last Monday (if today is Monday,
use today's date) and walk step by step seven days into the future.

6. Between February 1st and March 15, 2000, you want to read a 400 page
book.  Write a script called pages.pl that, if called at an arbitrary
day of this interval, shows how much time has elapsed and which page
you should accordingly have reached in your reading.  On February 1st,
the output should read:
                0.0% of time - page 0
On March 15th it should read:
                100.0% of time - page 400
Make use of Date::Manip to calculate the number of days between start
date and current date and between start date and end date to determine
percentages and ratios.

7. Write a CGI Script to implement a very simple "guestbook"-like
feature that allows users to post one-line comments to a Web page.
Keep track of all past  postings (as a file).  You can assume the
existence of an HTML form with two  elements:a text field called
mail for the E-mail address of the poster, and a text  field
called comment for comments by the poster. Indicate the URL to
run your script.

Questions about the questions? Robert Katz: katz@ned.highline.edu
Last Update May 12, 2003