Updated: 2017-01-20 00:52 EST

1 Due Date and DeliverablesIndexup to index

Do not print this assignment on paper!

WARNING: Some inattentive students upload Assignment #08 into the Assignment #07 upload area. Don’t make that mistake! Be exact.

2 Purpose and BackgroundIndexup to index

This assignment is based on your weekly Class Notes and covers these topics:

  1. Practice with setting Permissions.
  2. Practice setting Umask.

As noted above in the Prerequisites, parts of this assignment come from your answers in Worksheet #08 PDF.

3 How to complete this AssignmentIndexup to index

For full marks, follow these directions exactly:

  1. These tasks must be done in your account via Remote Login to the Course Linux Server.

  2. Do the tasks in order, from top to bottom. Do not skip steps. Most tasks are independent, but some depend on successful completion of a previous task.

  3. READ ALL THE WORDS in each task before you begin the task, especially all the Hints and links.

  4. Verify your own work before running the Checking Program. You won’t have a checking program at your job interview and the Checking Program is not guaranteed to check everything.

  5. Run the Checking Program at the end of the task to grade your work and help you find some of your errors. A perfect mark from the Checking Program does not mean your answers are correct.

  6. When you are done with this Assignment, submit the output of the Checking Program to Blackboard before the due date, following the directions given at the end of this Assignment.

3.1 Notes on doing assignment workIndexup to index

  1. You can use the Checking Program to check your work after you have completed each task.

    Most task sections below require you to finish the whole task section before running the Checking Program. You may not always be able to run the Checking Program successfully in the middle of a task or after every single task sub-step. The assignment tells you where you can safely check your work.

  2. You will create file system structure in your CLS home directory containing various directories and files. When you are finished the tasks, leave the files and directories in place on the CLS as part of your deliverables for your instructor to verify.

    Assignments may be re-marked at any time on the CLS; you must have your term work available on the CLS right until term end. Do not delete any assignment work until after the term is over!

  3. You can modify your work and check it with the Checking Program as often as you like before you submit your final mark to Blackboard. You can upload your marks to Blackboard as many times as you like before the due date. Partial marks are accepted.

  4. Your instructor will also mark on the due date the work you do in your account on the CLS. Leave all your work on the CLS and do not modify it after you have submitted your final mark to Blackboard.

3.2 Searching the course notes on the CLSIndexup to index

All course notes are available on the Internet and also on the CLS. You can learn about how to read and search these CLS 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.

3.3 The Source DirectoryIndexup to index

All references to the Source Directory below are to the CLS directory ~idallen/cst8207/16f/assignment08/ and that name starts with a tilde character ~ followed by a user name 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).

You do not have permission to list the names of all the files in the Source Directory, but you can access any files whose names you already know.

4 TasksIndexup to index

Have you completed all the prerequisites, before attempting these tasks?

4.1 Set Up – The Base Directory on the CLSIndexup to index

As mentioned in List of Commands You Should Know, you must keep a list of command names used each week and write down what each command does. Without that list to remind you of what command names to use, you will find assignments very difficult.

  1. Do a Remote Login to the Course Linux Server (CLS). All work in this assignment must be done on the CLS.

  2. Base Directory: Create the CLS directory ~/CST8207-16F/Assignments/assignment08 in which you will create the files and scripts resulting from the following tasks. (You do not have to create any directories that you have already created in a previous assignment.) Spelling and capitalization must be exactly as shown:

check

  1. Create the check symbolic link needed to run the Checking Program, as you did in your last assignment and as described in the section Checking Program below.

This assignment08 directory is called the Base Directory for most pathnames in this assignment. Store your files and answers in this Base Directory, not in your HOME directory or anywhere else.

Use the symbolic link to run the Checking Program to verify your work so far.

4.2 Part A: A file to record your permissionsIndexup to index

You need to understand Permissions for this task.

Record the permissions you set on each of the directories and files you create in the next Part, below. You will record these permissions by copying and editing a file that you get from your instructor.

You can record each of the permissions as you create things step-by-step in the next Part below, or you can record all of the permissions after you have finished the Part below, before you run the Checking Program.

You will need to complete the next Part, below, before you can finish recording all the permissions in this Part. The two Parts go together.

abcd0001.txt

  1. Copy the file record.txt from the Source Directory into your own file abcd0001.txt (no spaces) where the text abcd0001 userid is replaced by your own eight-character userid in the file name. This file copy should be located directly under your Base Directory.

  2. Fix the permissions on the file so that you can edit it and nobody else (group or other) has any permissions at all.

Note on the verb edit: To edit a file, you need to be able to read the contents of the file, change the contents, and write them back into the file. You do not need to execute the contents of the file unless you are editing a script file.

You will need to edit your copy of the file with a Linux command-line text editor. The VI Text Editor is recommended, since that is the universal text editor for system administrators.

  1. Edit the abcd0001.txt file you just created and replace the KEY line in the file with the output of running the program named key located in the Source Directory. When you run the key program, give it a single argument that is the basename of the file you are editing, i.e. abcd0001.txt

Hints on replacing the KEY line in the file:

  1. First, run the key program with the correct argument.
    You can make a symlink to or alias for the key program and run it that way; or, you can run it using its full absolute pathname, just as you have been running the Checking Program in the same directory. The output of the key program with the correct argument looks similar to this:

    KEY: abcd0001 BMf8xNDc4NDU0Mjky/2NzdDgyMDdi/zEwMDP/Zm9v/w==

    You must pass the key program one argument that is your abcd0001.txt basename file name. The correct output will be 1 line, 3 words, and approximately 72 characters including the newline.

  2. Edit the key program output into the abcd0001.txt file, replacing just the KEY line that is already in that file. Edit the abcd0001.txt file and replace the KEY line in that file with your new key program output.
    • You could run the key program and put its output into a temporary file, and then edit the abcd0001.txt file and read in that temporary file. (You did this in VIM vimtutor Lesson 5.4. RETRIEVING AND MERGING FILES.)
    • You could append the output of the key program to the bottom of the abcd0001.txt file and then edit the file to delete the old KEY line and replace it with the new one that you appended to the bottom of the file. (VIM makes moving lines easy.)
    • You could also replace just the KEY line using the VIM !! method from section 2.1 #10 in Worksheet #06 PDF. (This is my favourite method; this is how I would do it.)
    • You could copy-and-paste the key program output into your editor, replacing just the KEY line in the file.

Run the Checking Program to verify your work so far.

  1. As you work on Creating Structure below, continue to edit the file and replace each string of three underscore characters “___” in the file with the correct three-digit numeric (octal) permission value that you use in the next Part below.

Be careful not to make other accidental changes to the file. Note the word count at the bottom of the file. Your count must match exactly, at all times. If not, re-copy the file and start over.

  • The original file and the edited file must have identical word counts.
  • The three underscores at the end of each of the 13 lines must be replaced with three octal digits.
  • If you damage the file, using diff between the original and your edited version will be helpful in knowing what you changed.

4.3 Part B: Creating structure with permissionsIndexup to index

You need to understand Permissions for this task. Do the permissions section of Worksheet #08 PDF before continuing. Record all your answers for later quizzes.

Now you will create some directories and files, then set the correct permissions on them. The permissions to set are described below.

Because you are applying permissions to directories as a non-root user, be careful not to lock yourself out of directories by restricting permissions on them too soon. First, create all the file and directory structure from the top of the directory tree down, and then apply restrictive permissions afterward from the bottom of the tree upward, after you have created all the structure.

If you don’t apply permissions last, from the bottom up, you will deny yourself permissions that will prevent you from entering some directories lower down. Assign permissions from the bottom toward the top.

Create this set of directories and files, and set the permissions as given. Make sure you create directories where directories are required and files where files are required.

Usr Grp Ohr

  1. Underneath directory head create three three-letter directories named: Usr Grp Ohr
    1. Directory Usr has no permissions for group or other. The user can cd into it, but cannot create any new content nor use ls to see any files in it. Record the permissions.
    2. Directory Grp has no permissions for user or other. The group can cd into it and use ls in it, but cannot create any new content. Record the permissions.
    3. Directory Ohr has no permissions for user or group. Others have full permissions. Record the permissions.

rf wf xf

  1. Underneath directory Usr create three two-letter files named: rf wf xf
    1. None of the files have any permissions for group or other.
    2. File rf has read permission (only) for the user. Record the permissions.
    3. File wf has write permission (only) for the user. Record the permissions.
    4. File xf has execute permission (only) for the user. Record the permissions.

rd wr xc

  1. Underneath directory Grp create three two-letter files named: rd wr xc
    1. None of the files have any permissions for user or other.
    2. File rd has read and write permission (only) for the group. Record the permissions.
    3. File wr has write and execute permission (only) for the group. Record the permissions.
    4. File xc has read and execute permission (only) for the group. Record the permissions.

oth *** ???

  1. Underneath directory Ohr create three three-character files named: oth *** ??? (Some characters are meta-characters that are special to the shell and will need careful handling. Review Quoting.)
    1. None of the files have any permissions for user or group.
    2. File oth has full permissions for other. Record the permissions.
    3. File *** has no permissions for other. Record the permissions.
    4. File ??? has only write permission for other. Record the permissions.

Remember to Read All The Words above about working from top to bottom and then from bottom to top in this Part.

Run the Checking Program to verify your work so far.

4.4 Part C: Minimal PermissionsIndexup to index

You need to understand Permissions for this task. Do the permissions section of Worksheet #08 PDF before continuing. Record all your answers for later quizzes.

minimal.txt

  1. Copy the file minimal.txt from the Source Directory into your Base Directory.

  2. Fix the permissions on the file so that only you and your group can edit it. (See the Hints about the edit verb in Part A.)

  3. Edit the file and replace the KEY line in the file with the output of running the program named key located in the Source Directory. Give the program a single argument that is the file basename, i.e. minimal.txt (To execute this program, see the Hints from Part A.)

Run the Checking Program to verify your work so far.

  1. Edit the file and replace all the sets of three underscore characters “_” with your answers from Worksheet #08 PDF. Missing permissions should be given as dashes so that each set of three underscores is replaced with exactly three other characters, e.g. replace ___ with -w- not with -w or w.

Be careful not to make other accidental changes to the file. Note the word count at the bottom of the file. Your count must match exactly, at all times. If not, re-copy the file and start over.

  • The original file and the edited file must have identical word counts.
  • Every set of three underscores must be replaced with three permissions characters, as explained in the Summary of rwx permissions.
  • If you damage the file, using diff between the original and your edited version will be helpful in knowing what you changed.

Run the Checking Program to verify your work so far.

4.5 Part D: Using umask to mask default permissionsIndexup to index

You need to understand Umask for this task. Do the umask section of Worksheet #08 PDF before continuing. Record all your answers for later quizzes.

umask.txt

  1. Copy the file umask.txt from the Source Directory into your Base Directory.

  2. Fix the permissions on the file so that you can edit it and your group and others can only read it.

  3. Edit the file and replace the KEY line in the file with the output of running the program named key located in the Source Directory. Give the program a single argument that is the file basename, i.e. umask.txt

Run the Checking Program to verify your work so far.

  1. Edit the file and replace all the sets of three underscore characters “_” with the correct three-digit umask value that would result in each set of symbolic permissions for a new directory. (Optionally check your work by setting your umask to the above value and then creating and examining the permissions of a new directory.)

Be careful not to make other accidental changes to the file. Note the word count at the bottom of the file. Your count must match exactly, at all times. If not, re-copy the file and start over.

  • The original file and the edited file must have identical word counts.
  • The three underscores at the end of each of the nine lines must be replaced with three octal digits.
  • If you damage the file, using diff between the original and your edited version will be helpful in knowing what you changed.
  • Do not leave your umask set incorrectly after this exercise.

Run the Checking Program to verify your work so far.

4.6 When you are doneIndexup to index

That is all the tasks you need to do.

Read your CLS Linux EMail and remove any messages that may be waiting. See Reading EMail for help.

Check your work a final time using the Checking Program below and save the standard output of that program into a file as described below. Submit that file (and only that one file) to Blackboard following the directions below.

When you are done, log out of the CLS before you close your laptop or close the PuTTY window, by using the shell exit command:

$ exit

5 Checking, Marking, and Submitting your WorkIndexup to index

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 single file that is the output of the Checking Program to Blackboard.

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.

check

  1. There is a Checking Program named assignment08check in the Source Directory on the CLS. Create a symbolic link named check in your Base Directory that links to the above Checking Program in the Source Directory, as you did in a previous assignment.

  2. Execute the above Checking Program as a command line on the CLS. The checking program will check your work, assign you a mark, and display the output on your screen:

    $ ./check | less

    You may run the Checking Program as many times as you wish, allowing you 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 this assignment, and you like the mark displayed on your screen by the Checking Program, you must redirect only the standard output of the Checking Program into the text file assignment08.txt in your Base Directory on the CLS, like this:

    $ ./check >assignment08.txt
$ less assignment08.txt
    • Use standard output redirection with that exact assignment08.txt file name.
    • Use that exact name. Case (upper/lower case letters) matters.
    • Be absolutely accurate, as if your marks depended on it.
    • Do not edit the output file; the format is fixed.
    • Make sure the file actually contains the output of the Checking Program!
    • The file should contain, near the bottom, a line starting with: YOUR MARK for
    • Really! MAKE SURE THE FILE HAS YOUR MARKS IN IT!
  4. Transfer the above single file assignment08.txt (containing the output from the Checking Program) from the CLS to your local computer.
    • You may want to refer to the File Transfer page for how to transfer the file.
    • Verify that the file still contains all the output from the Checking Program.
    • Do not edit or open and save this file on your local computer! Edited or damaged files will not be marked. Submit the file exactly as given.
    • The file should contain, near the bottom, a line starting with: YOUR MARK for
    • Really! MAKE SURE THE FILE YOU UPLOAD HAS YOUR MARKS IN IT!
  5. Upload the assignment08.txt file from your local computer to the correct Assignment area on Blackboard (with the exact name) before the due date:
    1. On your local computer use a web browser to log in to Blackboard and go to the Blackboard page for this course.
    2. Go to the Blackboard Assignments area for the course, in the left side-bar menu, and under there find assignment08
    3. Under Assignments, click on the underlined assignment08 link for this assignment.
      1. If this is your first upload, the Upload Assignment page will open directly; skip the next sentence.
      2. If you have already uploaded previously, the Review Submission History page will be open and you must use the Start New button at the bottom of the page to get to the Upload Assignment page.
    4. On the Upload Assignment page, scroll down and beside Attach File use Browse My Computer to find and attach your assignment08.txt file from your local computer. Make sure the assignment file has the correct name on your local computer before you attach it. Attach only your assignment08.txt file for upload. Do not attach any other file names.
    5. After you have attached the assignment08.txt file on the Upload Assignment page, scroll down to the bottom of the page and use the Submit button to actually upload your attached assignment08.txt file to Blackboard.
    6. Submit the file exactly as uploaded from the CLS.
    7. Do not submit an empty file. Do not submit any other file names. Make sure the file name on Blackboard is correct!

    Use only Attach File, Browse My Computer on the Upload Assignment page. Do not enter any text into the Write Submission or Add Comments boxes on Blackboard; I do not read them. Use only the Attach File, Browse My Computer section followed by the Submit button. If you need to comment on any assignment submission, send me EMail.

    You can revise and upload the file more than once using the Start New button on the Review Submission History page to open a new Upload Assignment page. I only look at the most recent submission.

    You must upload the file with the correct name from your local computer; you cannot correct the name as you upload it to Blackboard. Make sure the file name on Blackboard is correct!

  6. Verify that Blackboard has received your submission: After using the Submit button, you will see a page titled Review Submission History that will show all your uploaded submissions for this assignment. Each of your submissions is called an Attempt on this page. A drop-down list of all your attempts is available.
    1. Verify that your latest Attempt has the correct 16-character, lower-case file name under the SUBMISSION heading.
    2. The one file name must be the only thing under the SUBMISSION heading. Only the one file name is allowed.
    3. No COMMENTS heading should be visible on the page. Do not enter any comments when you upload an assignment.
    4. Click on the Download button to open and view the file you just uploaded. MAKE SURE THE FILE YOU JUST UPLOADED HAS YOUR MARKS IN IT!
    5. Save a screen capture of the Review Submission History page on your local computer, showing the single uploaded file name listed under SUBMISSION. If you want to claim that you uploaded the file and Blackboard lost it, you will need this screen capture to prove that you actually uploaded the file. (To date, Blackboard has never lost an uploaded file.)
    6. Make sure you have used Submit and not Save as Draft. I cannot mark draft assignments. Make sure you Submit.

    You will also see the Review Submission History page any time you already have an assignment attempt uploaded and you click on the underlined assignment08 link. You can use the Start New button on this page to re-upload your assignment as many times as you like.

    You cannot delete an assignment attempt, but you can always upload a new version. I only mark the latest version.

  7. Your instructor may also mark files in your 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!

READ ALL THE WORDS. OH PLEASE, PLEASE, PLEASE READ ALL THE WORDS!

Author: 
| Ian! D. Allen, BA, MMath  -  idallen@idallen.ca  -  Ottawa, Ontario, Canada
| Home Page: http://idallen.com/   Contact Improv: http://contactimprov.ca/
| College professor (Free/Libre GNU+Linux) at: http://teaching.idallen.com/
| Defend digital freedom:  http://eff.org/  and have fun:  http://fools.ca/

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