KIT501 Operating Systems Assignment 2
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KIT501 UNIX Scripting Assignment
Due Date: 3:00pm Thursday the 30th of September – Week 11
Weight: 15% of your final KIT501 result
Introduction
There are two (2) shell programming tasks in this assignment. This is an individual assignment. You
are required to make a directory named kit501a2 under your home directory (on ictteach)
and use kit501a2 as your working directory for this assignment.
Assignment script submissions will be marked by the KIT501 tutors on ictteach. If you write and
test your scripts elsewhere it’s your responsibility to ensure that your scripts run correctly on the
School UNIX system (ictteach) – you must test your scripts run correctly on ictteach before
you submit. You must also submit your assignment scripts via this server as well as a screenshot of
your terminal/putty window to MyLO for feedback purposes (see Submitting Your Assignment
section).
Ø Please pay close attention to the marking scheme shown on the last page. This
scheme shows you how marks are allocated, and what you must (successfully)
achieve to receive marks. Note also that your scripts must have clear and tidy
structure, have good use of indentation and whitespace (to make the script
readable), include appropriate comments, and have your identification details
and the script’s purpose specified in comments at the top of your script.
Ø All scripts should be completed using syntax and commands discussed in past
(and some future) practical classes – no additional referential syntax is needed
(so your script solutions should not use alternative constructs and syntax
sourced from e.g. google that are not taught in the unit)
KIT501 ICT Systems Administration Fundamentals 2021 Unix Scripting Assignment
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Task A
Write a shell script (to run on the Bourne shell) that takes a filename as argument and then
compresses and decompresses the file using the following commands in turn:
Compression commands Decompression commands
1 bzip2 bunzip2
2 gzip gunzip
3 zip unzip
For each of the compression commands, the script must note the size of the file before and
after compression. Then, the script must display a simple table showing the name of the file
and:
• the compression command used,
• the file’s uncompressed size,
• the file’s compressed size.
Before using any compression command to manipulate the file, your script must verify that
the filename provided as an argument to your script actually exists under the current
directory and is readable. You must also use the matching decompression command listed
in the table above to restore the file to its uncompressed prior state in each case.
Specific Task A Requirements
1. Your script for this task must be named compr.sh.
2. Make sure your script is user-friendly and follows common sense – your script should use
consistent indentation and include whitespace/blank lines (where relevant) to make the
script more logical and easier for a person to read. You must also include general inline
comments in the script code to indicate the purpose of more complex command
combinations etc.
3. Your script must include comments at the start to specify:
a. the script’s purpose,
b. the author (including student number),
c. and the date (when last modified).
4. One filename must be supplied as an argument to be used by your script when it is executed
by the user.
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KIT501 ICT Systems Administration Fundamentals 2021 Unix Scripting Assignment
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5. Near the beginning of your script, you need to check that the file associated with the
filename provided as an argument to the script:
a. Exists under the current directory. If the file does not exist, your script must display
an error message and then it should exit.
b. Is readable. If the file is not readable, your script must display an error message and
then it should exit.
6. Your script must generate output similar to the example shown in the next subsection,
Task A Example output.
7. Clean up – remove all temporary files created (if any) at the end of your script and make sure
the file is in the original, decompressed state.
Ø Hints: You might like to research some of these UNIX commands and their
options: ls, cut,wc in addition to the compression/decompression
commands
Task A Example output
The following is a sample output of the script. The $ is the shell prompt and ff is an example file
name for a file that exists in the current directory:
$ ./compr.sh ff
File: ff
bzip2 174145 13976
gzip 174145 11746
zip 174145 11879
Ø This output shows that, before compressing, the size of the file named ff is
174145 bytes. After compressing using bzip2, its size becomes 13976 bytes.
After compressing using gzip, its size becomes 11746 bytes. After compressing
using zip, its size becomes 11879 bytes.
The table shows that, for the file ff, the most efficient compressing program is
gzip. Please note that the columns of the table must be left-aligned.
KIT501 ICT Systems Administration Fundamentals 2021 Unix Scripting Assignment
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Task B
Write a shell script (to run on the Bourne shell) that uses an infinite loop (i.e. it runs forever unless
interrupted by the control-c key sequence) to check every 3 seconds to report on who logs into and
who logs out of a UNIX system. To simplify the script, you can ignore multiple logins from the same
user during a time period of less than 3 seconds, or cases where a user logs in and logs out during the
same 3 second time period.
Specific Task B Requirements
1. Your script for this task must be named log.sh
2. Make sure your script is user-friendly and follows common sense – your script should use
consistent indentation and include whitespace/blank lines (where relevant) to make the
script more logical and easier for a person to read. You must also include general inline
comments in the script code to indicate the purpose of more complex command
combinations etc.
3. Your script must include comments at the start to specify:
a. the script’s purpose,
b. the author (including student number),
c. and the date (when last modified).
4. When the script starts executing, it must display the following:
The current time is:
followed by (on the next line) the current date and time e.g.
Wed Sep 1 13:18:32 AEST 2021
5. The script must then display a sorted list of usernames of users who are currently logged in:
(using example usernames)
The current users are:
dherbert
jsmithe
sxu
6. Then, every three seconds, the script must display a list of users who have logged in, followed
by a list of users who have logged out: (using example usernames)
User abcd has logged in.
User jsmith has logged in.
User dherbert has logged out.
User jsmithe has logged out.
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KIT501 ICT Systems Administration Fundamentals 2021 Unix Scripting Assignment
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If no user logged in or out during a three second period, then the following message should
be displayed:
No user has logged in/out in the last 3 seconds.
Ø Hints: You could research some of these UNIX commands and their options:
who, cut, sort, cmp,grep.
Task B Example output
The following is a sample output of the script (It is OK if the script leaves behind a temporary file
when it is finally interrupted). The $ is the shell prompt.
$ ./log.sh
The current time is:
Wed Sep 1 13:18:32 AEST 2021
The current users are:
Dherbert
jsmithe
sxu
No user has logged in/out in the last 3 seconds.
No user has logged in/out in the last 3 seconds.
User abcd has logged in.
User jsmith has logged in.
No user has logged in/out in the last 3 seconds.
User abcd has logged out.
User dherbert has logged out.
No user has logged in/out in the last 3 seconds.
… … … … … … … … etc
KIT501 ICT Systems Administration Fundamentals 2021 Unix Scripting Assignment
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Submitting Your Assignment
You must make two submissions – one to MyLO and one on the teaching server, ictteach directly.
The MyLO submission is purely for attaching your assignment feedback to, whereas the ictteach
submission is your script files.
MyLO submission:
In order to provide individual feedback through MyLO for this assignment, there needs to be some
submission in MyLO to attach the feedback to. You must submit a screenshot (picture) of your
terminal/putty window showing a connection to ictteach. Note the contents of this screenshot
itself will not be assessed, so it’s not important to display any file in the output of your
terminal/putty window – a picture of the shell prompt (which will show your username) will do. You
must submit this screenshot via Assessments → Assignments → Assignment 2 (scripting) –
screenshot before the submission cut-off time. If you do not submit this part, you may not receive
individual feedback.
ictteach submission:
This is the most important submission – you must submit (copy) a single folder named kit501a2
which contains the following two (2) files to the kit501submit folder which was automatically
created for you in your ictteach account:
compr.sh, log.sh
Please ensure your kit501a2 folder only contains the two files as listed here, when you are ready
to submit your assignment.
Ø WARNING: Do not manually create the kit501submit folder using the
mkdir command in your home directory, the folder should already be created
for you (unless you deleted it) – if you see this folder in your home directory, DO
NOT DELETE IT.
Please read below for further details.
To submit your assignment, follow these steps:
1. Verify you have the KIT501submit submission folder link (note – this is NOT a normal
directory, it is a softlink). See the section Verify the kit501submit submission folder exists.
2. If you are missing the submission folder link, or it is just a normal directory, create your
submission folder link. See the section Create the KIT501submit submission folder.
3. Ensure that both your kit501a2 folder and the kit501submit folder are present under
your home directory.
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4. Type the following commands to copy your kit501a2 folder into your kit501submit folder
(the $ is the shell prompt):
$ cd (This takes you back to your home directory
from anywhere)
$ cp -r kit501a2 kit501submit (This copies your assignment folder into your kit501submit
folder. The option -r is important)
$ ls -l kit501submit (Verify that your assignment folder is now in your
kit501submit folder)
$ ls -l kit501submit/kit501a2 (Verify that your assignment files are now in your
kit501submit folder)
Verify the kit501submit submission folder exists
1. Verify your kit501submit submission folder exists with following commands ($ is the
shell prompt and username is your username)
$ cd
$ ls -l | grep kit501submit
Other output.. kit501submit -> /u/submissions/kit501/username
2. The important part to note is highlighted above. The kit501submit folder is actually a
softlink to another folder elsewhere in the filesystem. The shell is displaying this fact by
including an arrow (->) and then the ultimate location the softlink refers to. If your
kit501submit folder does not look like this (or it is missing), then you need to create the
softlink – see the next section.
Create the kit501submit submission folder
Ø Only perform this section if you are missing the kit501submit folder softlink.
1. If you had a manually-created kit501submit folder and you want to keep anything it
contains, use the following commands to create a backup prior to removing it ($ is the shell
prompt and username is your username):
$ cd
$ mv kit501submit kit501BACKUP
$ rm -r kit501submit
2. Create the kit501submit submission folder with following command ($ is the shell
prompt and username is your username)
KIT501 ICT Systems Administration Fundamentals 2021 Unix Scripting Assignment
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$ cd
$ ln -s /u/submissions/kit501/username kit501submit
Late submission?
If your assignment is late then you should submit your script files to the kit501late folder on
ictteach (as well as a screenshot of your terminal/putty window to MyLO). This kit501late
folder will be created immediately after the assignment due date and it will be available for one
week only. Do not create this folder yourself, it will be created automatically. After submitting late
by following the steps below, make sure not to touch your late submission files in the kit501late
folder as this will change the recorded timestamps. The submitted files will be copied after 24 hours
late and 1 week late.
$ cd (This takes you back to your home directory
from anywhere)
$ cp -r kit501a2 kit501late (This copies your assignment folder into your kit501late
folder. The option -r is important)
$ ls -l kit501late (Verify that your assignment folder is now in your
kit501late folder)
$ ls -l kit501late/kit501a2 (Verify that your assignment files are now in your
kit501latet folder)
Need Help?
You are encouraged to seek assistance from your lecturer or tutor after you have seriously thought
about the assignment. Please note that we can provide general advice – but you are expected to
write and debug (correct) your own code.
When writing your script, think about what steps you need to do, don’t try to write the code all at
once. Implement a small part first, test that it is working correctly, then implement a bit more,
repeating the process of thinking, writing (coding), testing and refining/fixing.
If you are still stuck, some suggested hints are given below, but your solution may be implemented
differently – that’s ok!
Task A Extra Hints:
• Start by determining the provided filename from the script’s argument parameters
• Verify the file exists – exit if it doesn’t
• Verify the file is readable – exit if it isn’t
KIT501 ICT Systems Administration Fundamentals 2021 Unix Scripting Assignment
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• Work out how to determine the file’s size – there are several ways to do this, and you then
need to only capture (remember) a certain portion of the output from the command(s) you
chose to achieve this (specifically where the file’s size is reported)
• Work out (test) how the compression commands work, and what sort of output they create
• Compress the file and work out how to then determine the file’s new size (like before)
• Display a row of the table output that contains the compression command used and the
before and after file sizes
• Decompress the file (using the appropriate command) and repeat the process for the other
compression commands
Task B Extra Hints:
• Work out how to determine who is logged in – you only want the username part of the
output
• Remember the list of users you’ve found above to a file (imagine this is the first list)
• Create a loop that will run every 3 seconds
• Within the loop, determine again who is logged in (saving the username results to another
file – imagine this is the second list). Compare this list of usernames with the first list you
saved before. Differences between the files indicate usernames who have logged in or out –
for each file you may have to use another loop to go through each username in turn in order
to determine if it’s present (or not) in the other file. For example, if a user “bob” is in the first
list of usernames but not the second list of usernames, then bob has logged out. If bob is in
the second list but not the first list, then bob has logged in. If both lists are exactly the same,
then no-one has logged in or out.
• Each iteration of your loop, the second list of usernames from before should become the first
list of usernames (they are now old, from 3 seconds in the past) so you can then compare it
with a (new) second list of usernames that have just been found.
• Some users might be logged in multiple times at once, so when you generate a list of who’s
logged in, your list should be sorted and only contain unique usernames…
Plagiarism
Plagiarism is a very serious matter, and ignorance of this is not an excuse. If you submit work
claiming it to be your own, and it is not original work of your own, this is cheating. This means for
example that you cannot submit large sections of code written by other students or sourced from
the Internet and claim you wrote the code yourself. Plagiarism can result in academic penalties both
in relation to your assignment, and also on your permanent university record.
Acknowledgements:
This assignment has been re-formatted and modified from an assignment written by Dr Shuxiang Xu.
KIT501 ICT Systems Administration Fundamentals 2021 Unix Scripting Assignment
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KIT501 Assignment 2 Marking Scheme
Task A – compr.sh Out of
Overall execution of the shell script
Script runs as expected (2)
2
Script Comments
Appropriate comments (in-line and at start of script) (2)
2
Script Layout
Appropriate layout, including indentation and whitespace (2)
2
File Verification
Filename is provided by a script parameter (argument) (1)
File specified by the filename argument is verified to exist and be readable, exiting
otherwise (2)
3
File size determination
Correctly determine the size of the file before and after compression (4)
4
Compression
Correctly use bzip2, gzip, and zip to compress the file (2)
2
Output
Correctly display an output table which shows the specified information (2)
The columns of the table are left-aligned as required (2)
4
Cleanup
Remove any temporary files and ensure file is in the original decompressed state (1)
1
Total 20
Task B – log.sh Out of
Overall execution of the shell script
Script runs as expected (2)
2
Script Comments
Appropriate comments (in-line and at start of script) (2)
2
Script Layout
Appropriate layout, including indentation and whitespace (2)
2
Initial Output
Display the message “The current time is:” followed by the current time (2)
Display a sorted list of usernames of users who are currently logged in at the start (2)
4
Continuing Output
Repeat output correctly every 3 seconds (2)
Correctly report users who have logged in since the last report (3)
Correctly report users who have logged out since the last report (3)
Correctly display “No user has logged in/out in the last 3 seconds.” (2)
10
Total 20
Assignment Total: 40