Updated: 2014-03-20 20:17 EDT
Do not print this assignment on paper!
- On paper, you will miss updates, corrections, and hints added to the online version.
- On paper, you cannot follow any of the hyperlink URLs that lead you to hints and course notes relevant to answering a question.
- On paper, scrolling text boxes will be cut off and not print properly.
23h59 (11:59pm) Friday January 24, 2014 (end of Week 3)
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.
This is an overview of how you are expected to complete this assignment. Read all the words before you start working.
You will create file system structure in your HOME directory, with various directories, files, and links. You can use the Checking Program to check your work as you do the tasks. You can check your work with the checking program as often as you like before you submit your final mark. (Some tasks sections below require you to finish the whole section before running the checking program; you may not always be able to run the checking program successfully after every single task step.)
When you are finished the tasks, leave these files, directories, and links 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.
This is a review lab, and all of the tasks can be completed with knowledge of the material from the prerequisite course CST8207 GNU/Linux Operating Systems I; however, you will probably need to refresh your memory of various topics by referring to the CST8207 course notes and the Linux man pages. Your lab instructor is there to help you, but s/he will want you to have tried consulting the notes and man pages first.
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.
All references to the “Source Directory” below are to the CLS directory ~idallen/cst8177/14w/assignment01/
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).
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. Pay particular attention to the special non-Algonquin password you must use, or else you will lock yourself out of the machine. All work in this assignment must be done on the CLS.
Create the following directory structure in your CLS HOME directory and record (for study purposes) the series of Unix commands you used to create it. Spelling and capitalization must be exactly as shown:
CST8177-14W
`-- Assignments
`-- assignment01
This directory is the base directory for most pathnames in this assignment. Store your files and answers here.
There is a Checking Program named assignment01check
in the Source Directory on the CLS. Follow the instructions in the first two steps at the start of Checking Program to create a working symbolic link to this program.
Check your work so far using the assignment01check
program symlink.
From your HOME directory, use the ls
command with options to give a long listing (showing permissions), include all hidden files, include inode numbers, and recursively include all subdirectories. (Do not use any other options.) When the output is correct, redirect the output of this command into new file listing_start
under assignment01
- it will be at least 16 lines of output. (If you have files from CST8207 in your account, you may get some “permission denied” errors doing the listing [ignore the errors] and the number will be many more than 16 lines.)
Run the whoami
command. When the output is correct, redirect the output of this command into new file whoami
under assignment01
Run the id
command. When the output is correct, append the output of this command to existing file whoami
under assignment01
. (Note the word append). The file must now have two lines of output in it. Check it!
Rename the file whoami
to have the new name whoamiid
(in the same directory) and make extra sure you spelled the new name correctly.
Use a command to count only the number of lines (not characters or words) in file read.txt
in the Source Directory. (You’ll know you have the right file if the size is 818 characters.) When the output is correct, redirect the output of this command (the output containing only the line count number, not any other numbers) into new file readlines
under assignment01
Use a command to search for and display the single line containing the exact text phrase “permissions is useless
” located inside any one of the text files (files having a .txt
file extension) located in the notes/
directory of the previous term CST8207 (fall 2013). The Introduction and Overview explains where to find these notes and how to search them, just as you did last term. When the output is correct, redirect the one line of output of this command into new file useless
under assignment01
The file should be one line long.
Check your work so far using the assignment01check
program symlink.
Copy the binary program file /bin/hostname
three times to files named read_only
, write_only
, and execute_only
under your assignment01
directory. This is a BINARY program file, so do not display the content of the file on your terminal screen!
Change the permissions on all three copied files so that group and other have no permissions. (You can do this with one command name and a file GLOB pattern.)
read_only
file so that only you can read the file but not write or execute the file.
/dev/null
.write_only
file so that only you can write (including append to) the file but not read or execute the file.
execute_only
file so that only you can execute the file but not read or write the file.
Check your work so far using the assignment01check
program symlink.
Make the following directory structure under assignment01/
permissions/
permissions/read_only/
permissions/write_only/
permissions/execute_only/
Change the permissions on the permissions/
directory so the owner (you) can read, write, and search, but group and other have no permissions.
Change the permissions on all three subdirectories of permissions/
so that that group and other have no permissions. (You can do this with one command name and a file GLOB pattern.)
Change the permissions on read_only/
so that you can see the names in the directory (with echo read_only/*
or similar), but cannot take an accurate long listing, and cannot create files, and cannot cd
into the directory. (Verify that you can/cannot do these things!)
Hint: Of course echo read_only/*
will only show file names if you actually create those files.
Change the permissions on write_only/
so that you cannot see the names in the directory, but you can add new files to the directory, delete files from the directory, and cd
into the directory. (Verify that you can/cannot do these things!)
Change the permissions on execute_only/
so that you can (only) cd
into the directory. You cannot see the names in the directory or add or delete files from the directory. Verify!
Check your work so far using the assignment01check
program symlink.
Under the Source Directory there is a directory named maze
(four letters). This maze contains many hidden sub-directories. Use a single command (no pipes needed) to find in the maze a single hidden file with a basename similar to .abcd0001*txt
, but look for the basename that starts with a period followed by your own Blackboard userid, not the fake userid abcd0001
. To look for the file, replace the string abcd0001
in .abcd0001*txt
with your own userid before you look. The basename you find must be exactly 13 characters long and contain a period and a real asterisk. It must have no leading or trailing blanks around it.
Hint#1: You might want to use a command that finds files by basename to do this. (Do not try to use “cd” and “ls” to find your file; the maze is really big.)
Hint#2: If you want to find a name containing a real asterisk, you may need to escape the asterisk to stop it from being used as a pattern character (wildcard), and you need to do this both for the shell that reads your command line and for the command that finds the files. if you get the escaping right, you will find exactly one file.
When you find the right file basename (there is only one for your userid), put its shortest full absolute pathname into new file foundmaze
under your assignment01
directory. Note: Shortest absolute pathnames contain no /./
or /../
or tilde (“~
”) expressions; simplify the path to the shortest possible absolute pathname.
Check your work so far using the assignment01check
program symlink.
Create an absolute soft Symbolic Link to the Linux password file; create the symlink under your assignment01
directory and name the symlink mypasswd
and verify you can read the text in the password file through the mypasswd
symbolic link. (The text of the new mypasswd
symlink should be an absolute pathname to the password file.)
Display file attributes and inode numbers of both the password file and the mypasswd
symbolic link, and confirm that they are different.
Make a new relative soft link to the mypasswd
symlink you just created, named alsopasswd
, also in the assignment01
directory. (The text of the new alsopasswd
symlink should be the shortest relative pathname to mypasswd
in the same directory.) Now, alsopasswd
links to mypasswd
that links to the password file. Make sure you can also read the password file using the new alsopasswd
symlink.
Hint: All of “././foo
” and “./foo
” and “foo
” are relative pathnames that lead to the same place. Which one is the shortest? Always use the shortest relative pathname.
Rename the mypasswd
symlink to be otherpasswd
. Now, alsopasswd
is a (broken) symlink to a non-existent mypasswd
symlink. Confirm that you can no longer use alsopasswd
to read the text of the password file.
Check your work so far using the assignment01check
program symlink.
Create a hard link to the read.txt
file in the Source Directory (you counted the lines in this file earlier); name the hard link hardread
in the assignment01
directory. (Note; On some versions of Unix/Linux, you are not allowed to hard link to a file you cannot write. That protection has been disabled on the CLS.) Verify that you can read the file using the hardread
hard link.
Display file attributes and inode numbers of both the read.txt
file and the hardread
hard link, and confirm that they are identical. (Only the pathnames will be different.) These hard links are just two names for the same file inode.
Make a new hard link to hardread
named newhard
in the same assignment01
directory.
Display file attributes and inode numbers of the read.txt
file and both the new hard link files, and confirm that all three are identical. (Only the pathnames will be different.) These hard links are just three names for the same file inode.
Rename hardread
to junkread
and note that this does not break the hard link for newhard
. Verify that all three files have the same attributes and inode numbers and that you can read the text of the read.txt
file through both hard links, as before.
Check your work so far using the assignment01check
program symlink.
Make a backup copy of your listing_start
file, in case you accidentally overwrite it in the next step.
From the same starting directory, repeat the command you used to create listing_start
at the beginning of this lab, but redirect the output this time into the file listing_end
in the same directory as listing_start
, and make sure that all errors (standard error output) also go into the output file and not on the screen. (You might find your shell history useful here. There is a special syntax to also redirect error messages.)
Use the diff
command to compare the earlier listing file to the previous one you did before starting this lab. Note the many changes!
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.
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.
There is a Checking Program named assignment01check
in the Source Directory on the CLS. Create a Symbolic Link to this program named check
under your new assignment01
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.
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.
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 assignment01.txt
under your assignment01
directory. Use the exact name assignment01.txt
in your assignment01
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!
Transfer the above assignment01.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.
Submit the assignment01.txt
file under the correct Assignment area on Blackboard (with the exact name) before the due date. Upload the file via the assignment01 “Upload Assignment” facility in Blackboard: click on the underlined assignment01 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.)
Your instructor may also mark the assignment01
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 EMAIL, WORD PROCESSOR, PDF, RTF, or HTML DOCUMENTS ACCEPTED.
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.
READ ALL THE WORDS. OH PLEASE, PLEASE, PLEASE READ ALL THE WORDS!
Author:
| Todd Kelly and
| Ian! D. Allen - 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/
Plain Text - plain text version of this page in Pandoc Markdown format
Author Ian! D. Allen