Due Date: 23h59 (11:59pm) Friday January 25, 2013 (end of Week 3)
You have three weeks to do this review assignment, but your next
assignment will be available in one week and will overlap this
assignment. Don’t delay!
Late assignments or wrong file names may not be marked. Be accurate.
an ability to READ ALL THE WORDS to work effectively
Deliverables:
One text file uploaded to Blackboard according to the
steps in the Checking Program section below.
Directory structure created and left for marking on the
Course Linux Server (CLS). Do not delete any assignment work from the CLS until after the
term is over!
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 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.
Remember to READ ALL THE WORDS to work effectively and not waste time.
All references to the “Source Directory” below are to the directory
~idallen/cst8177/13w/assignment01/ and that name starts with a
tilde character followed by a userid with no intervening slash.
Log in remotely to the Course Linux Server (CLS) from any
existing computer. Pay particular attention to the special
non-Algonquin password you must use, or else you will lock
yourself out of the machine. If the public DNS name doesn’t work
on campus (time out), try the Algonquin private name instead.
All work in this assignment must be done on the CLS.
Ensure you have set the seven BASH shell options and five BASH
aliases in your $HOME/.bashrc as recommended in CST8207 Startup
Files. If these options and aliases are not set when you log in,
edit the .bashrc file to add them and then log out and log back
in. If they still aren’t set, also fix your $HOME/.bash_profile
file to source your .bashrc file, as shown.
We recommend adding the following two additional shell options:
shopt -s cmdhist
shopt -s histappend
In your home directory, create a directory called: Assignments
(As with all Unix/Linux pathnames, be precise in the spelling
and capitalization.) In this document, Assignments/ refers
to this directory that contains all your course Assignments.
Under Assignments/, create a directory named: assignment01
(As with all Unix/Linux pathnames, be precise in the spelling
and capitalization.) All output files in the assignment must go
under this assignment01/ directory. Put output files here.
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. To verify the symbolic link, try executing it
(just as you did last term).
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 2012). 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.)
Change the permissions on the read_only file so that only you
can read the file but not write or execute the file.
Verify readability of the file by using any command that reads
the content of the file. For example, you can word count the file
or try to copy the file to /dev/null.
Verify non-writability by attempting to re-copy
/bin/hostname to the file. (It should fail with
“permission denied”.)
Verify non-executability by attempting to execute the file as a
program. (It should fail with “permission denied”.) You may
need to review how to execute a file using a pathname. The
error must be “permission denied” not “no such file” or
“command not found”.
Change the permissions on the write_only file so that only you
can write (including append to) the file but not read or execute the file.
Using operations similar to the previous file, verify that you
can write the file but not read or execute it.
Change the permissions on the execute_only file so that only
you can execute the file but not read or write the file.
Using operations similar to the previous files, verify that you
can execute the file but not read or write it.
Check your work so far using the assignment01check program symlink.
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!)
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.
This section refers to the maze of partially hidden files and directories
under directory ~idallen/cst8177/13w/assignment01/maze
Find in the maze a single hidden file with a name similar to
.abcd0001*txt, but look for the name 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 name 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: 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.)
When you find the right file name (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 shortest?
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.
Note 2012-01-07: This section has been rewritten not to use the
password file, because of inode changes when the file is updated.
-IAN!
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!
Check your work a final time using the assignment01check program
symlink. Submit your final mark following the directions below.
5 Checking, Marking, and Submitting your WorkIndex
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. To verify the symbolic link, try executing it.
Execute the above “check” program using its symbolic link.
(Review the CST8207 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.
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. You only
get one chance to get the name correct. Case (upper/lower case
letters) matters. Be absolutely accurate, as if your marks depended
on it. Do not edit the file.
Transfer the above assignment01.txt file from the CLS to your local
computer and verify its contents. Do not edit this file! No empty
files, please! Edited or damaged files will not be marked. You may
want to refer to this updated page on File Transfer.
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 / Richard Donnelly 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/
