Updated: 2014-03-20 20:17 EDT

1 Due Date and Deliverables

Do not print this assignment on paper!

2 Purpose of this Assignment

Do not print this assignment on paper! On paper, you cannot follow any of the hyperlink URLs that lead you to hints and course notes relevant to answering a question.

  1. Practise with regular expressions of varying complexity
  2. Create simple shell scripts
  3. Practise with a text editor

3 Introduction and Overview

This is an overview of how you are expected to complete this assignment. Read all the words before you start working.

  1. Complete the Tasks listed below.
  2. Verify your own work before running the Checking Program.
  3. Run the Checking Program to help you find errors.
  4. Submit the output of the Checking Program to Blackboard before the due date.
  5. READ ALL THE WORDS to work effectively and not waste time.

You are given a file of somewhat random text, and a set of descriptions of sets of lines in that file. For each description, you are to produce a regular expression that will match the described set of lines. You will initially test your regular expressions on the command line, and when you are satisfied with each one, you will put the grep command in a shell script. A Checking Program is available to check your work as you go.

The following tasks (except the first three, which should be done once) are to be repeated for each description.

When you are finished the tasks, leave the files and directories in place as part of your deliverables. Do not delete any assignment work until after the term is over! Assignments may be re-marked at any time; you must have your term work available right until term end.

The prevous term’s course notes are available on the Internet here: CST8207 GNU/Linux Operating Systems I. All the notes files are also on the CLS. You can learn about how to read and search these files using the command line on the CLS under the heading Copies of the CST8207 course notes near the bottom of the page Course Linux Server.

Since I also do manual marking of student assignments, your final mark may not be the same as the mark submitted using the current version of the Checking Program. I do not guarantee that any version of the Checking Program will find all the errors in your work. Complete your assignments according to the specifications, not according to the incomplete set of the mistakes detected by the Checking Program.

3.1 The Source Directory

All references to the “Source Directory” below are to the CLS directory ~idallen/cst8177/14w/assignment03/ and that name starts with a tilde character ~ followed by a userid with no intervening slash. The leading tilde indicates to the shell that the pathname starts with the HOME directory of the account idallen (seven letters).

4 Tasks

4.1 Set Up

  1. Do a Remote Login to the Course Linux Server (CLS) from any existing computer, using the name appropriate for whether you are on-campus or off-campus. All work in this assignment must be done on the CLS.

  2. Make an assignment03 directory in the same directory as you made assignment02 in a previous assignment.

    This directory is the base directory for most pathnames in this assignment. Store your files and answers here.

  3. The file foo.txt in the Source Directory contains many lines of text. Put a soft link to this file in your new assignment03 directory. Use the same name for the link.

  4. In your new assignment03 directory create a soft link named check to the checking program assignment03check from the Source Directory.

4.2 Regular Expressions

Below, in the Labelled Descriptions section, you are given labelled descriptions of lines to find in the file foo.txt. For each labelled description you will repeat these two steps (described in detail below):

  1. On the command line, invent a grep command using a single basic regular expression that will match the described lines of text (and nothing more). Do not use any options to grep (except possibly for the last question). You do not need multiple expressions or any extended regular expressions or special expressions except possibly for the last question. Use basic regular expressions.
  2. Put the working grep command into its own shell script.

Each set of lines to be found is labelled below with a label. The label is the first word in the section, followed by a colon. For example, the following example description is labelled bar:

bar: lines that contain the word barbar

Repeat the following steps for each of the labelled descriptions:

4.2.1 Repeat these steps for each label

  1. Make your current working directory the base directory (the directory containing the new link you made to the foo.txt file) if it is not already so.

  2. You must find lines in the foo.txt file using a single grep command. Type directly at the command line your initial attempt at a grep command that finds the lines, and view the result on your screen. The correct answer in all cases will result in less than 50 lines of text on your screen.

    No pipes are allowed. Use only a single grep command.

    For the example given above with the label bar, a grep command you might try could be:

    $ grep 'barbar' foo.txt
  3. If you’re not satisfied with your initial attempt, use up-arrow to retrieve the previous command, and make changes to the regular expression, then re-run the new command. Repeat the this step until you’re satisfied with the output on your screen and want to check your answer.

  4. To check your answer, use up-arrow to retrieve the command, and modify it to pipe the output of your command into the wc program, then do the same, changing wc to sum. Compare the output of wc and sum with the values output by the Checking Program.

    For the example given above with the label bar, the checking pipelines would be done like this, in this order:

    $ grep 'barbar' foo.txt
    $ grep 'barbar' foo.txt | wc
    $ grep 'barbar' foo.txt | sum

    The 'barbar' string is the quoted regular expression.

  5. If the word count or checksum values differ, you need to change your regular expression. Use up-arrow to retrieve the command, make your changes to the regular expression, and re-run the command.

  6. When you are satisfied with your answer as typed on the command line, use a text editor to create in your assignment03 directory an executable shell script whose name is the label name followed by .sh that simply runs your grep command without the piping of its output to the check program. Just copy the grep command from the command line into the last line of the new shell script.

    For the example given above with the label bar, the script name must be bar.sh in the assignment03 directory.

    The first few lines of every shell script must correspond exactly to the Script Header described in class.

    The last line of every script will be your grep command. Do not redirect or pipe the output of your command into anything – the script should produce the correct lines of output from foo.txt on your screen so that it can be checked.

    Do not put any lines into your script other than the Script Header, the single grep command line, and optional blank or comment lines.

  7. You can also check the output of your script using the wc and sum commands, similar to the way you checked the original grep command. The script must output exactly the same lines as the original grep command that you put into it. The results should be identical:

    $ grep 'barbar' foo.txt | wc
    $ ./bar.sh              | wc
    $ grep 'barbar' foo.txt | sum
    $ ./bar.sh              | sum
  8. Repeat the 8 steps in this section for each of the Labelled Descriptions below.

NOTE: When it comes time to create your second and subsequent scripts, copy the previous script to the new label name rather than starting from scratch every time. Run the Checking Program to make sure you have copied the Script Header correctly.

Do not put any lines into your script other than the Script Header, the single grep command line, and optional blank or comment lines.

4.3 Labelled Descriptions

Repeat the 8 steps of the above section for each of these labelled items below. None of these expressions except the very last one require any options to grep, nor multiple expressions, nor do they require any extended regular expressions.

All except the last must be solved with no options and only one single basic regular expression.

Definition: Whitespace
Spaces or space-like characters such as TABs, newlines, carriage-returns, form-feeds, etc. This is a distinct POSIX character class from blanks, which are only space and TAB. This assignment uses Whitespace, not blanks.
  1. label: description of desired grep output from in file foo.txt

  2. upper: lines containing at least one upper case alphabetic character.

  3. control: lines containing at least one control character. (When checking your output, you can make control characters visible using the -vT options to the cat command, otherwise they won’t show on your screen. Do not put the cat command in your script.)

  4. punct: lines containing at least one punctuation character.

  5. blank: blank lines. (A blank line contains only zero or more Whitespace characters and no other kinds of characters.)

  6. only_alpha: non-empty lines containing only alphabetic characters. (“Non-empty” means there has to be at least one character.)

  7. only_digit: non-empty lines containing only digits.

  8. only_alnum: non-empty lines containing only alphanumeric characters.

  9. only_upper: non-empty lines containing only upper case characters.

  10. no_white: lines containing no Whitespace characters. Another way of saying this is: lines containing zero or more only non-Whitespace characters.

  11. no_num_white: lines containing no Whitespace or digit characters. Another way of saying this is: lines containing zero or more only non-Whitespace non-digit characters.

  12. empty: empty lines. (An empty line means nothing on the line, not even Whitespace characters. The line contains no characters.)

  13. plus: lines containing at least one plus + character.

  14. question: lines containing at least one question mark ? character.

  15. backslash: lines containing at least one backslash \ character.

  16. caret: lines containing at least one circumflex/caret ^ character.

  17. star: lines containing at least one asterisk * character.

  18. dot: lines containing at least one period . character.

  19. square: lines containing at least one square bracket [ or ] character.

  20. begin_end: lines that start with the exact five characters begin and that end with the exact three characters end. (Any other characters might appear between the begin and the end.)

  21. AB: lines containing A and B, capitalized and in that order but not necessarily right next to each other. Another way of saying this is: lines containing a B following an A.

  22. first: lines that start with optional Whitespace, then the string first.

  23. capital: lines that contain the string Capital where the initial letter C must be upper-case but the rest of the letters could be either case, e.g. CAPTIAL, CaPiTaL, etc..

  24. first_last: lines that start with the exact five characters first preceded by any amount of Whitespace and that end with the exact four characters last followed by any amount of Whitespace. (Any other characters might appear between the first and the last, but only optional Whitespace is allowed before first and after last.) (Hint: Another way of saying this: The line starts with optional Whitespace, followed by first, followed by anything, followed by last, followed by optional Whitespace, and then the end of the line.)

  25. phone: lines that contain a seven-(or more)-digit number with one or more dashes between the group of three (or more) digits and the group of four (or more) digits. These should match: 555-1212, 555555-----121212121212, x555-1212x, x555---1212x, x999555-1212x, x555-1212999x x999555-1212999x, but these would not match: 555-121x, x55-1212, 5551212

  26. better_phone: lines that contain a seven-digit number, surrounded before and after with non-digit characters, with one or more underscores, dashes, or periods between the third and fourth digits. These should match: x555-1212x, x555.1212x, x555_-.1212x, x555--__..-_.1212x but these would not match: 555555-----121212121212, x999555-1212x, x555-1212999x x999555-1212999x, 555-121x, x55-1212, 5551212

  27. password: lines containing password or passwd, with the p optionally capitalized. These would match: Password, password, Passwd, but these would not match Pass, passwD, paSsword, passw, or passd. (Hint: There is a solution to this that permits grep to use multiple search patterns, or you can use a single extended regular expression. This is the only question in which you may use an option or extended regexp.)

4.4 Additional Testing

I’ve added a second test file bar.txt to the Source Directory containing additional test material designed to find more problems in your regular expressions that weren’t detected by the foo.txt file. Error messages from the checking program will tell you which file is being read to detect the errors in your script.

Your scripts must also give the correct output word count and checksum results when searching in this bar.txt test file. If the output is incorrect, you will be told what the correct values should be in the error message. Do not save this message - the bar.txt file may change at any time and your scripts must still match the correct lines.

Write the basic regular expressions to match the given pattern specifications, not to match the particular set of lines in the given test files. I may come up with other test cases even after the due date of the assignment; your script loses marks if it fails these tests because it doesn’t do what the specification says it must do. You may have to write your own test cases, to be sure you got it right.

I’ve also set up the checking program to detect failure to protect special characters from shell GLOB expansion. If your expression works in your account but not when the checking script runs it, this may be your problem. You may also see “Permission denied” errors if this is the problem. Fix your script.

4.5 When you are done

That is all the tasks you need to do.

Check your work a final time using the Checking Program and save the output as described below. Submit your mark following the directions below.

5 Checking, Marking, and Submitting your Work

Summary: Do some tasks, then run the checking program to verify your work as you go. You can run the checking program as often as you want. When you have the best mark, upload the marks file to Blackboard.

  1. There is a Checking Program named assignment03check in the Source Directory on the CLS. Create a [Symbolic Link] to this program named check under your new assignment03 directory so that you can easily run the program to check your work and assign your work a mark. Note: You can create a symbolic link to this executable program but you do not have permission to read or copy the program file.

  2. Execute the above “check” program using its new symbolic link. (Review the Search Path notes if you forget how to run a program by pathname from the command line.) This program will check your work, assign you a mark, and display the output on your screen. (You may want to paginate the long output so you can read all of it.)

    You may run the “check” program as many times as you wish, to correct mistakes and get the best mark. Some task sections require you to finish the whole section before running the checking program at the end; you may not always be able to run the checking program successfully after every single task step.

  3. When you are done with checking this assignment, and you like what you see on your screen, redirect the output of the Checking Program into the text file assignment03.txt under your assignment03 directory. Use the exact name assignment03.txt in your assignment03 directory. Case (upper/lower case letters) matters. Be absolutely accurate, as if your marks depended on it. Do not edit the file. Make sure the file actually contains the output of the checking program!

  4. Transfer the above assignment03.txt file from the CLS to your local computer and verify that the file still contains all the output from the checking program. Do not edit this file! No empty files, please! Edited or damaged files will not be marked. You may want to refer to your File Transfer notes.

  5. Submit the assignment03.txt file under the correct Assignment area on Blackboard (with the exact name) before the due date. Upload the file via the assignment03 “Upload Assignment” facility in Blackboard: click on the underlined assignment03 link in Blackboard. Use “Attach File” and “Submit” to upload your plain text file.

    No word-processor documents. Do not send email. Use only “Attach File”. Do not enter any text into the Submission or Comments boxes on Blackboard; I do not read them. Use only the “Attach File” section followed by the Submit button. (If you want to send me comments about your assignment, use email.)

  6. Your instructor may also mark the assignment03 directory in your CLS account after the due date. Leave everything there on the CLS. Do not delete any assignment work from the CLS until after the term is over!

Use the exact file name given above. Upload only one single file of plain text, not HTML, not MSWord. No fonts, no word-processing. Plain text only.

Did I mention that the format is plain text (suitable for VIM/Nano/Pico/Gedit or Notepad)?


No marks are awarded for submitting under the wrong assignment number or for using the wrong file name. Use the exact name given above.

WARNING: Some inattentive students don’t read all these words. Don’t make that mistake! Be exact.


| Todd Kelly and
| Ian! D. Allen  -  idallen@idallen.ca  -  Ottawa, Ontario, Canada
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