Updated: 2015-03-30 11:06 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.
15h00 (3pm) Tuesday March 31, 2015 (start of Week 12)
WARNING: Some inattentive students upload Assignment #11 into the Assignment #10 upload area. Don’t make that mistake! Be exact.
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 assignment is based on your weekly Class Notes.
tar
archives from Package Managementcron
and at
)Remember to READ ALL THE WORDS to work effectively and not waste time.
This is an overview of how you are expected to complete this assignment. Read all the words before you start working.
For full marks, follow these directions exactly.
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/cst8207/15w/assignment11/
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.
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.
You must keep a list of command names used each week and write down what each command does, as described in the List of Commands You Should Know. Without that list to remind you what command names to use, you will find assignments very difficult.
Do a Remote Login to the Course Linux Server (CLS) from any existing computer, using the host name appropriate for whether you are on-campus or off-campus.
Make the CLS directory ~/CST8207-15W/Assignments/assignment11
in which you will create the files and scripts resulting from the following tasks.
Create the check
symbolic link needed to run the Checking Program, as described in the section Checking Program below.
This assignment11
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.
tar
Archive and ListingIndexYou need to know Disk Usage and Package Management to do this task.
3maze
abcd0001
In the current directory (the Base Directory), create a directory named 3maze
. Without changing directories, create a symbolic link in that 3maze
directory that is the name of your 8-character CLS userid. The symlink should point to the absolute path of the maze
directory that is in the Assignment #03 Source Directory. The symbolic link will have a size of exactly 43 characters (the absolute path of the maze
directory), e.g. for userid abcd0001
the symlink long listing would start like this:
lrwxrwxrwx 1 abcd0001 abcd0001 43 Mar 22 12:03 3maze/abcd0001 ->
The rest of the symlink is the absolute path of the maze
directory.
You probably have it right if ls 3maze/abcd0001
shows about 1700 (non-hidden) pathnames from the maze.
3maze/abcd0001/.0
sub-directory inside the maze.
abcd0001
mazeblocks.txt
mazeblocks.txt
in the 3maze
directory.
YYYYMMDD
.tar.gz
tar
archive in the 3maze
directory containing the contents of the .0
directory from above. Use the relative pathname from above as the source of the files to archive. Name the new archive YYYYMMDD
.tar.gz
(no spaces) under 3maze
, where YYYYMMDD
is the numeric year-month-day date of the final exam in this course.
tar
archive file must be relative paths with 3maze/abcd0001/.0/
at the beginning of every name.YYYYMMDD
.tar.bz2
tar
archive in the 3maze
directory of the same .0
directory from above. Use the same name as for the gzip archive, but use the file extension .bz2
instead of the .gz
extension.
ls
that gives “the allocated size of each file, in blocks” and use that option (and only that option) to display the size and name of the two tar
archives you just created in the 3maze
directory.
3maze
directory.mazeblocks.txt
ls
changes to separate lines when output is to a file instead of directly to your screen. This is one of the few commands that does this.tar
archives are much smaller (fewer disk blocks) than the original disk space used.tar_tvzf.txt
Generate a verbose listing of your gzip-style tar
archive file, showing the contents of the archive including all the owners and date/time stamps, but don’t display it directly on your screen since it’s over 1,500 lines long. Save just the first five and last five lines of the verbose listing into file tar_tvzf.txt
under 3maze
directory. The file word count will be 10 60 751
and the first line and last line should look like this (where abcd0001
is replaced by your userid):
drwxr-xr-x idallen/idallen 0 2012-02-13 13:33 3maze/abcd0001/.0/
drwxr-xr-x idallen/idallen 0 2012-02-13 13:33 3maze/abcd0001/.0/.1/.1/.1/
Hint: You will need to use one command pipeline to generate the first five lines into the output file, and a second command pipeline to generate the last five lines and append them to the output file to make a total of ten lines in the file.
The bzip2 compression algorithm is better than the gzip compression algorithm; bzip2 produces smaller compressed files. Answer this question:
True or False: Because bzip2 is smaller than gzip, generating the verbose table of contents of the bzip2-style tar
archive file will produce fewer lines than the table of contents of the gzip-style archive. Append your one-word answer true
or false
to the tar_tvzf.txt
file. (The file will now contain 11 lines.) (The checking program will not check this answer. Your instructor will check the answer and mark it after you hand in your assignment.)
Run the Checking Program on the CLS to verify your work so far.
If you have errors, go back and re-read the first step in this task.
You need to know Processes and Jobs to do this task.
psbsd.txt
Place a full list of all processes for all users, BSD format, all users, text user name (not numeric UID), full wide listing (not truncated at all), into file psbsd.txt
in your Base Directory. It should be at least 105 lines and 9KB. The header line and one of the very long lines will be a dhclient
line similar to this (use a text-searching command to find it in the output):
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 4078 0.0 0.0 7264 388 ? Ss Mar15 0:00 dhclient3 -e IF_METRIC=9999 -pf /var/run/dhclient.eth0.pid -lf /var/lib/dhcp/dhclient.eth0.leases -1 eth0
psunix.txt
Place a full list of all processes for all users, UNIX (System V) format, text user name (not numeric UID), full wide listing (not truncated at all), into file psunix.txt
in your Base Directory. It should be at least 105 lines and 7KB. The header line and one of the very long lines will be a dhclient
line similar to this (use a text-searching command to find it in the output):
UID PID PPID C STIME TTY TIME CMD
root 4078 1 0 Mar15 ? 00:00:00 dhclient3 -e IF_METRIC=9999 -pf /var/run/dhclient.eth0.pid -lf /var/lib/dhcp/dhclient.eth0.leases -1 eth0
mine.txt
psbsd.txt
file and put the one line into file mine.txt
. (1 11 73 mine.txt
)
psbsd.txt
that contain your userid anywhere in the line and append those lines to the mine.txt
file. (Some of the lines in this file may be very long.)vi thesis
IndexYou need to know about Job Control and Background Processes to do this section.
We will now create a symbolic link named vi thesis
that will run a command that has a different name. The ps
command will show the vi thesis
name of the symlink, not the name of the program that is the target actually being run. Users or attackers may use this symlink trick to hide the actual name of a command that they are using.
vi thesis
vi thesis
in your Base Directory that points to (has as a target) the absolute pathname of the system sleep
command.
sleep
command name. See “Commands related to PATH” in Search Path. You need to remember how to create a Symbolic Link.vi thesis
name and making sure it prints the same checksum number as a checksum of the real sleep
program file.
vi thesis: No such file or directory
, you didn’t get the symbolic link correct.vi: No such file or directory
, you forgot to hide the blank in the name from the shell. See Quoting.Run your new vi thesis
command (that name is in the current directory) as a background job with a single argument of 999
(that the command will interpret as a number of seconds to sleep). Your shell will print a shell background job number and process ID similar to: [1] 12345
Hints: You need to remember how to execute a command in the current directory, and how to run a job in the background. You need to know how to hide blanks (in the command name) from the shell. If you got the symlink correct, you can use the TAB key to ask the shell to complete the command name in the current directory. You do not need any “seconds” qualifier on the 999
number; the number defaults to seconds. If you create more than one background job, the job number will be bigger than [1]
.
thesis.txt
Confirm that your vi thesis
command is running by asking the shell for a listing of jobs of the shell that includes the process ID of the jobs. It will look similar to this (note the process ID is included by using an option):
[1]+ 12345 Running ./vi\ thesis 999 &
Redirect the above output (showing the PID number) into file thesis.txt
in your Base Directory. If you have more than one background job, the job numbers will be bigger than [1]
.
Run the ps
command and you should see output similar to this:
PID TTY TIME CMD
12345 pts/5 00:00:00 vi thesis
15000 pts/5 00:00:00 ps
22460 pts/5 00:00:00 bash
Note the vi thesis
command, which is really sleep
, and could be made to be any command you like if you change the symlink target. (The command name shown by ps
is not necessarily accurate.)
Append the above ps
output to your thesis.txt
file. The file will have at least five lines in it.
Kill the job, using the special shell syntax for its job number. When you next push the [Enter]
key, you should see: [1]+ Terminated ./vi\ thesis 999
If you have more than one background job, the job numbers will be bigger than [1]
.
Run the Checking Program on the CLS to verify your work so far.
You need to know System Log Files to do this task.
syslog.txt
psbsd.txt
and psunix.txt
that contains this name and redirect the results (two lines, one from each file) into file syslog.txt
. (The result will be 2 lines, 21 words.)authlog.txt
The system authentication log file is named auth.log
in the system log directory. Generate an ls
long listing showing inode number of this file using the full absolute pathname, and put the results of the ls
(the output of ls
) into file authlog.txt
. (The result of the ls
command should be 1 line, 9 words, at least 60 characters.)
(Optional: You may find it convenient to set a shell variable to this absolute pathname, so that you can use the short variable name rather than the long absolute pathname in the rest of these exercises. Or, you could make a short symbolic link to this file.)
id.txt
id.txt
. The result will be 1 (long) line, 3 words. See Permissions for the command to use to do this. Do not edit the output of the command.myperms.txt
id.txt
and authlog.txt
files. Note that your account is in a group that matches the group of the system auth.log
file, giving you group permissions on this file. Using a text editor, put the matching group name, the symbolic group permissions (three characters), and the octal group permissions (one digit), onto three lines in file myperms.txt
. (The result will be 3 lines, 3 words, 10 characters. Do you remember why a file containing seven alphanumeric characters on three lines is counted as a 10-character file on Linux? Review Line End Differences.)authhead.txt
auth.log
file contains (March 2015) over 2,222,310 lines. Use a command to extract just the first line (one line) from the head of this file and redirect that one line into new file authhead.txt
. (The result will be 1 line 14 words 111 chars.) The time and date at the start of this line is when this copy of the log file was started.failedpass.txt
auth.log
containing the exact text string Failed password
, the count is more than 7,820 lines (March 2015). Of those lines (the lines containing that exact text string), extract just lines 100 through 110 (inclusive) and put only those lines into file failedpass.txt
. The word count for the file will be 11 174 1279
. Every line should contain the exact text string somewhere.Run the Checking Program on the CLS to verify your work so far.
You need to know Crontab and At Job Schedulers to do this task. Re-read the Notes on checking your work before you continue.
crontab.txt
Create a personal crontab
entry that uses a command to update the (access and) modification time on file crontab.txt
in your Base Directory (not in your HOME
directory) every minute of every day. Use the shortest relative pathname to your crontab.txt
file. Do not use an absolute pathname. Verify that the time of the file changes every minute.
Hints: If it doesn’t work, read your Linux EMail for EMail messages from the Cron daemon showing possible errors. See Reading EMail for help. The single working crontab
line should be seven words: five for the date/time, a command name, and a relative file name.
crontab1.txt
List your personal crontab
(one entry, with perhaps some comment lines) and redirect the output into file crontab1.txt
in your Base Directory. This entry should run every minute.
Delete your personal crontab
(the one that runs every minute).
crontab.txt
crontab
entry that redirects the current date and time into the same file crontab.txt
at The Crontab Time. Also use a relative pathname, not an absolute pathname.crontab2.txt
crontab
(one entry, with perhaps some comment lines) and redirect the output into file crontab2.txt
. Do not delete this personal crontab
entry; leave it for marking. Make sure your displayed cron
job is scheduled at The Crontab Time.Run the Checking Program on the CLS to verify your work so far.
Re-read the Notes on checking your work if you are trying to check your work in the middle of a task instead of at the end of a task.
You need to know Crontab and At Job Schedulers to do this task.
Create an at
job that prints the list of users on the system, one per line, at The Crontab Time in the year 2016. You can use any of several commands to show the list of users one per line; see the List of Commands You Should Know.
Hints: You need to get the order of the date correct on the at
command line; see the Crontab and At Job Schedulers course notes or RTFM to find out how to specify both a time and a date for an at
job. No pipes are needed for this at
job; it’s just one command name.
Display your list of at
jobs to confirm the correct scheduling date and time in 2016.
Create an at
job that runs the command that prints the name of this computer at The Crontab Time in the year 2016.
Hints: You used this same command name in an assigment shell script recently.
Create an at
job that echoes the one line of text Exam 11am Today
to your Algonquin Live EMail account at 1 AM on the date of your final exam in this course. The EMail message sent at 1am must have the exact three-word echo text and exact five-word subject: CST8207 Final Exam 11AM Today
Hints: A pipe will be needed to connect the one-line output of echo
with the standard input of the mail program. See Sending EMail for help in sending EMail with a subject line. Did you use the exact words given to you for the echo and Subject texts?
Check the queue of at
jobs and make sure the scheduled times are correct.
Delete the at
job that shows the list of users.
atjob.txt
Display both your queued at
jobs and redirect the output into file atjob.txt
. You will only have two jobs – two lines. If you have more than two lines, delete the other jobs.
Leave these two jobs queued on the CLS for marking.
Run the Checking Program on the CLS to verify your work so far.
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
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.
There is a Checking Program named assignment11check
in the Source Directory on the CLS. You can execute this program by typing its (long) pathname into the shell as a command name:
$ ~idallen/cst8207/15w/assignment11/assignment11check
You learn one way to make this shorter in the current assignment.
Execute the above Checking Program as a command line on the CLS. This program will check your work, assign you a mark, and display the output on your screen.
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.
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 assignment11.txt
in your Base Directory on the CLS, like this:
$ ~idallen/cst8207/15w/assignment11/assignment11check >assignment11.txt
$ cat assignment11.txt
assignment11.txt
file name.YOUR MARK for
assignment11.txt
(containing the output from the Checking Program) from the CLS to your local computer.
YOUR MARK for
assignment11.txt
file from your local computer to the correct Assignment area on Blackboard (with the exact name) before the due date:
Use only Attach File on the Upload Assignment page. Do not enter any text into the Text Submission or Comments boxes on Blackboard; I do not read them. Use only the Attach File 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.
You will also see the Review Submission History page any time you already have an assignment attempt uploaded and you click on the underlined assignment11 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.
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!
I do not accept any assignment submissions by EMail. Use only the Blackboard Attach File. No word processor documents. Plain Text only.
Use the exact file name given above. Upload only one single file of Linux-format plain text, not HTML, not RTF, not MSWord. No fonts, no word-processing. Linux plain text only.
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 16-character, lower-case 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!
This section shows you how to calculate your personal Crontab Time for use in your cron and at jobs. You need to know your nine-digit student number and how to calculate the arithmetic modulus of a number.
- Take your 9-digit student number and remove the first three digits (probably
040
), leaving six digits. Use these last six digits as follows:- Take the first two of those six digits as a number, modulo 12, and then add 1, giving a number between 1 and 12. This is your month number.
- Take the next (middle) two of those six digits as a number, modulo 24, giving a number between 0 and 23. This is your hour number.
- Take the last two of those six digits as a number, modulo 60, giving a number between 0 and 59. This is your minute number.
- Take the same last two of those six digits as a number, modulo 28, and then add 1, giving a number between 1 and 28. This is your day-of-the-month number.
For example, if your nine-digit student number were 123456789
:
123
, leaving the last six digits 45 67 89
45
, the month would be (45 mod 12) + 1 = 10
(October)67
, the hour would be 67 mod 24 = 19
(7pm)89
, the minute would be 89 mod 60 = 29
89
, the day of the month would be (89 mod 28) + 1 = 6
The Crontab Time for student number 123456789
is October 6 at 19h29 (7:29pm).
Exercise: Show that The Crontab Time for student number 987654321
is
65 43 21
6
(June)19
(7pm)21
22
which is June 22 at 19h21 (7:21pm).