24T2 Practice Exam

You have been given the file awards.psv

This file contains information about Nobel Prize, Turing Award and Fields Medal winners

Each line in the file contains the following six fields:

1. Award Name
2. Award Year
3. Winner Name
4. Winner Gender
5. Winner Country
6. Winner Birth Year

Each field is separated from the next field by a pipe character (|).

Your task is to write four grep(1) commands which will print specified lines from this file.

You have been given the file practice_q1.txt.

In practice_q1.txt add answers to the four questions.

Add each answer in the specified location.

Do not add, remove, or change any other text in the file.

The autotest depends on the exact format of the file.

Each question should be answered with a single grep(1) command.

You may use any regular expression syntax supported by grep(1).

You may use any options supported by grep(1) except -P/--perl-regexp.

1. Question 1

   Write a grep(1) command that will print the lines in awards.psv that contain awards won by an Australian.

2. Question 2

   Write a grep(1) command that will print the lines in awards.psv that contain a female ACM Turing Award winner.

3. Question 3

   Write a grep(1) command that will print the lines in awards.psv that contain Nobel Prizes won by a person born between 1990 and 1999 (inclusive).

4. Question 4

   Write a grep(1) command that will print the lines in awards.psv that contain awards won by a person with first name, last name, and middle initial starting with the same letter.

Your example to each question will be a single grep command.

You can test the command by running it in the terminal.

For example, if you think the answer to question 1 is grep -E 'Andrew' awards.psv,
you can test it:

grep -E 'Andrew' awards.psv
ACM Turing Award|2000|Andrew Chi-Chih Yao|Male|China|1946
Nobel Prize for medicine|1963|Andrew F. Huxley|Male|United Kingdom|1917
Nobel Prize for medicine|2006|Andrew Z. Fire|Male|United States|1959
Nobel Prize for medicine|1977|Andrew V. Schally|Male|United States|1926
ACM Turing Award|2017|David Andrew Patterson|Male|United States|1947

Autotest will extract your answers from practice_q1.txt and do a simple test.

When you think your program is working, you can run some simple automated tests:

2041 autotest practice_q1

When you are finished working on this activity, you must submit your work by running give:

give cs2041 practice_q1 practice_q1.txt

To verify your submissions for this activity:

2041 classrun -check

We have student enrolment data in this familiar format:

cat enrollments.txt
COMP1511|3360379|Costner, Kevin Augustus          |3978/1|M
COMP1511|3364562|Carey, Mary                      |3711/1|M
COMP3311|3383025|Thorpe, Ian Augustus             |3978/3|M
COMP4920|3860448|Steenburgen, Mary Nell           |3978/3|F
COMP1521|3360582|Neeson, Liam                     |3711/2|M
COMP3411|3863711|Klum, Heidi June Anne            |3978/3|F
COMP3141|3383025|Thorpe, Ian Augustus             |3978/3|M
COMP3891|3863711|Klum, Heidi June Anne            |3978/3|F
COMP3331|3383025|Thorpe, Ian Augustus             |3978/3|M
COMP2041|3860448|Steenburgen, Mary Nell           |3978/3|F
COMP2041|3360582|Neeson, Liam                     |3711/2|M
COMP3311|3711611|Klum, Mary                       |3978/3|F
COMP3311|3371161|Thorpe, Ian Fredrick             |3711/3|M
COMP3331|5122456|Wang, Wei                        |3978/2|M
COMP3331|5456732|Wang, Wei                        |3648/3|M
COMP4920|5456732|Wang, Wei                        |3648/3|M

You should find a copy of the above data in the provided file enrollments.txt.

Each line in the file contains the following five fields:

1. UNSW Course Code
2. Student ID Number
3. Student Name (surname(s), given-names(s))
4. Student Plan
5. Student Gender

Each field is separated from the next field by a pipe character (|).

In practice_q2.sh, write a shell pipeline that,
given student enrollment data, on stdin, in the above format,
will output the surnames (family names) of male students.

Each surname should be printed only once

The surnames should be printed in alphabetical order.

For example, given the above data, your pipeline should output this:

./practice_q2.sh < enrollments.txt
Carey
Costner
Neeson
Thorpe
Wang

Using the additional data file provided,
your pipeline should output this:

./practice_q2.sh < more_enrollments.txt
Bai
Bian
Cai
Cui
Guo
Islam
Kumar
Li
Long
Lu
Luong
Luu
Murray
Ngo
Saha
Tran
Trinh
Wu
Xia
Xiao
Yao
Ye
Yip
Yong
Zeng

When you think your program is working, you can run some simple automated tests:

2041 autotest practice_q2

When you are finished working on this activity, you must submit your work by running give:

give cs2041 practice_q2 practice_q2.sh

To verify your submissions for this activity:

2041 classrun -check

Write a Python program practice_q3.py that performs the same task as the Shell pipeline in the previous question.

In other words: given data in the same format as the last question on standard input,
output the surnames (family names) of male students.

Each surname should be printed only once

The surnames should be printed in alphabetical order.

For example:

./practice_q3.py < enrollments.txt
Carey
Costner
Neeson
Thorpe
Wang

When you think your program is working, you can run some simple automated tests:

2041 autotest practice_q3

When you are finished working on this activity, you must submit your work by running give:

give cs2041 practice_q3 practice_q3.py

To verify your submissions for this activity:

2041 classrun -check

Write a POSIX-compatible shell script ./practice_q4.sh that takes a single command-line argument, a filename.

The file will contain an unordered list of positive integers, one per line, from n to m, with possibly one integer missing.

Your shell script should print the missing integer, if there is a missing integer.

If there is no missing integer your script should print nothing.

No integer will occur twice.

At most one integer will be missing.

The missing integer will not be n or m.

For example, ./practice_q4.sh should output this:

cat numbers_1.txt
39
45
40
44
41
43
./practice_q4.sh numbers_1.txt
42
cat numbers_2.txt
6
8
9
1
7
2
3
10
11
12
5
./practice_q4.sh numbers_2.txt
4
./practice_q4.sh numbers_3.txt
1005
./practice_q4.sh numbers_4.txt

When you think your program is working, you can run some simple automated tests:

2041 autotest practice_q4

When you are finished working on this activity, you must submit your work by running give:

give cs2041 practice_q4 practice_q4.sh

To verify your submissions for this activity:

2041 classrun -check

In question 1 you were given the file awards.psv

containing information about Nobel Prizes, Turing Awards and Fields Medal winners

This time we are interested in the years particular awards were not given, between when it was first offered and when it was last offered.

Write a POSIX-compatible Shell script practice_q5.sh that prints all years that an award was not given in.

practice_q5.sh will be given two command-line arguments, a regular expression and a file name,
practice_q5.sh should print in sorted order the years that no award whose entirename matches the regex given.

The entire name must match the regex not just a substring.

For example if the regex is Nobel Prize, then awards for Nobel Prize for physics should not match.
But if the regex is Nobel Prize.*, then awards for Nobel Prize for physics should match.

You should not hard code the name of this file in your script, the name of the data file will be given as the second command-line argument.

If there are no awards that match the regex, then practice_q5.sh should print an message to stdout as below.

For example, the Nobel prize for physics was first awarded in 1901 and last awarded in 2021.
It was not awarded in these six years:

./practice_q5.sh 'Nobel Prize for physics' awards.psv
1916
1931
1934
1940
1941
1942

./practice_q5.sh 'Nobel Prize for (chemistry|physics)' awards.psv
1916
1940
1941
1942
./practice_q5.sh 'Nobel Prize for.*' awards.psv
1940
1941
1942
./practice_q5.sh 'COMP2041 Distinguished Achievers' awards.psv
No award matching 'COMP2041 Distinguished Achievers'

When you think your program is working, you can run some simple automated tests:

2041 autotest practice_q5

When you are finished working on this activity, you must submit your work by running give:

give cs2041 practice_q5 practice_q5.sh

To verify your submissions for this activity:

2041 classrun -check

Two files are mirrored if they contain the same lines but in the reverse order to each other.

Write a Python program practice_q6.py that given two filenames checks if the two files are mirrored.

practice_q6.py should always produce one line of output.

If the two files are mirrored practice_q6.py should print a message indicating this.

If the two files are not mirrored practice_q6.py should print a message indicating why not.

Match the example output below exactly:

If the two files contain a different number of lines,
practice_q6.py should print a single line indicating this, including the number of lines in each file.

This message should be printed in exactly the format below.

echo hello >file1
echo Andrew >>file1
echo Dylan >file2
cat file1
hello
Andrew
cat file2
Dylan
./practice_q6.py file1 file2
Not mirrored: different number of lines: 2 versus 1
./practice_q6.py file2 file1
Not mirrored: different number of lines: 1 versus 2

If the files contain the same number of lines but a line in the first file
is not the same as the corresponding line in the second file in reverse order,
practice_q6.py should print a single line indicating this.

The message should indicate the line number in the first file (only).

The message should be printed in exactly the format below.

echo hello >>file2
cat file1
hello
Andrew
cat file2
Dylan
hello
./practice_q6.py file1 file2
Not mirrored: line 2 different
./practice_q6.py file2 file1
Not mirrored: line 1 different

Note, message should only be for the first line which is different.
The example below shows files where multiple lines are different.

sed -i s/hello/hi/ file1
cat file1
hi
Andrew
cat file2
Dylan
hello
./practice_q6.py file1 file2
Not mirrored: line 1 different
./practice_q6.py file2 file1
Not mirrored: line 1 different

The example below shows mirrored files.

echo hello >file3
echo Dylan >>file3
cat file3
hello
Dylan
cat file2
Dylan
hello
./practice_q6.py file2 file3
Mirrored
seq 1 5 >a
seq 5 -1 1 >b
cat a
1
2
3
4
5
cat b
5
4
3
2
1
./practice_q6.py a b
Mirrored

When you think your program is working, you can run some simple automated tests:

2041 autotest practice_q6

When you are finished working on this activity, you must submit your work by running give:

give cs2041 practice_q6 practice_q6.py

To verify your submissions for this activity:

2041 classrun -check

We have many executable scripts which we want to rename with an extension if possible.

Reminder, a filename extension is a suffix on the end of a filename that indicates the file contents.
For example, an extension of .sh can be used to indicate a file contains a shell script.

Write a POSIX-compatible Shell script practice_q7.sh which given one or more filenames as command-line arguments,
prints shell commands to add extensions to the filenames.

We need to check the commands before executing them, so practice_q7.sh should print the commands, not execute them.

For each filename, practice_q7.sh should print one line of output to stdout,
matching the example output below exactly.

• If the filename already has an extension (contains a '.'),
  print a line indicating this.
• If the file does not start with #!,
  print a line indicating this.
• If the #! line does not contain any of the strings, perl, python or sh,
  print a line indicating this.
• If a file already exists with the new filename created by adding the appropriate extension,
  print a line indicating this.
• Otherwise, practice_q7.sh should print a line containing a command to rename the file.

The line printed for each filename should match the example output below exactly.
For example:

touch script.rs
./practice_q7.sh script.rs
# script.rs already has an extension
./practice_q7.sh script1
# script1 does not have a #! line
./practice_q7.sh script2
# script2 no extension for #! line
practice_q7.sh script3
mv script3 script3.py
./practice_q7.sh script*
# script1 does not have a #! line
# script2 no extension for #! line
mv script3 script3.py
mv script4 script4.pl
mv script5 script5.sh
touch script4.pl
./practice_q7.sh script4
# script4.pl already exists

When you think your program is working, you can run some simple automated tests:

2041 autotest practice_q7

When you are finished working on this activity, you must submit your work by running give:

give cs2041 practice_q7 practice_q7.sh

To verify your submissions for this activity:

2041 classrun -check

We wish to save disk space by replacing identical copies of files with symbolic links.

Write a POSIX-compatible shell script practice_q8.sh, which takes 0 or more names of files as arguments, and prints commands to replace some of the files with symbolic links.

We need to check the commands before executing them, so practice_q8.sh should print the commands, not execute them.

For each file specified as an argument, if the file has identical contents (bytes) to any previous file specified as an argument, practice_q8.sh should print a ln(1) command which would replace the file with a symbolic link to the previous file.

practice_q8.sh should just print the ln(1) command, it should not execute the ln(1) command.

If none of the files can be replaced by symbolic links, practice_q8.sh should print a message exactly as shown in the last example below.

Your script must work when executed with /bin/dash on a CSE system, and must only use the external programs listed below.

Make your program produce exactly the output indicated by the example below.

For example, here is how your program should behave:

./practice_q8.sh file0.txt file1.txt file2.txt file3.txt file4.txt file5.txt file6.txt file7.txt file8.txt
ln -s file0.txt file3.txt
ln -s file1.txt file6.txt
ln -s file2.txt file5.txt
ln -s file2.txt file7.txt
./practice_q8.sh file6.txt file4.txt file1.txt file2.txt file3.txt file5.txt file7.txt file8.txt file0.txt
ln -s file6.txt file1.txt
ln -s file2.txt file5.txt
ln -s file2.txt file7.txt
ln -s file3.txt file0.txt
./practice_q8.sh file8.txt file7.txt file6.txt file5.txt file4.txt file3.txt file2.txt file1.txt file0.txt
ln -s file7.txt file5.txt
ln -s file7.txt file2.txt
ln -s file6.txt file1.txt
ln -s file3.txt file0.txt
./practice_q8.sh file1.txt file2.txt file3.txt file4.txt file5.txt file6.txt
ln -s file1.txt file6.txt
ln -s file2.txt file5.txt
./practice_q8.sh file0.txt file1.txt file2.txt file3.txt file4.txt
ln -s file0.txt file3.txt
./practice_q8.sh file3.txt file0.txt
ln -s file3.txt file0.txt
./practice_q8.sh file3.txt file0.txt file3.txt file0.txt file3.txt file0.txt file3.txt file0.txt
ln -s file3.txt file0.txt
./practice_q8.sh file1.txt file2.txt file3.txt file4.txt
No files can be replaced by symbolic links

When you think your program is working, you can run some simple automated tests:

2041 autotest practice_q8

When you are finished working on this activity, you must submit your work by running give:

give cs2041 practice_q8 practice_q8.sh

To verify your submissions for this activity:

2041 classrun -check

Write a Python program, practice_q9.py, which takes two command line argument, a positive integer n and the name of a file.

the single positive integer, n, indicating a maximum desired line length.

Your program should change the file in the following way:

• Lines containing n characters or less, not including the new line, should not be changed.

• Lines not containing a space character (' ') should not be changed.

• Lines containing more than n characters with a space in the first n characters,
  should have the last space in the first n characters changed to a newline character ('\n').

• Lines containing more than n characters without a space in the first n characters,
  should have the first space on the line changed to a newline character ('\n').

The above rules should also be applied to new lines as they are created.

Your program should not print anything to stdout.
The only thing it should do is change the file in-place.

For example:

echo hello there how are you today > hello.txt
./practice_q9.py 80 hello.txt
cat hello.txt
hello there how are you today
./practice_q9.py 23 hello.txt
cat hello.txt
hello there how are
you today
./practice_q9.py 12 hello.txt
cat hello.txt
hello there
how are you
today
./practice_q9.py 6 hello.txt
cat hello.txt
hello
there
how
are
you
today
cp frost.txt f.txt
cat f.txt 
I shall be telling this with a sigh
Somewhere ages and ages hence:
Two roads diverged in a wood, and I --
I took the one less traveled by,
And that has made all the difference.
./practice_q9.py 20 f.txt
cat f.txt 
I shall be telling
this with a sigh
Somewhere ages and
ages hence:
Two roads diverged
in a wood, and I --
I took the one less
traveled by,
And that has made
all the difference.
./practice_q9.py 10 f.txt
cat f.txt 
I shall
be telling
this with
a sigh
Somewhere
ages and
ages
hence:
Two roads
diverged
in a
wood, and
I --
I took
the one
less
traveled
by,
And that
has made
all the
difference.

Note practice_q9.py printed nothing - it changed the file it was given as argument.

Make sure your program does this.

When you think your program is working, you can run some simple automated tests:

2041 autotest practice_q9

When you are finished working on this activity, you must submit your work by running give:

give cs2041 practice_q9 practice_q9.py

To verify your submissions for this activity:

2041 classrun -check

Write a Python program, practice_q10.py, that reads lines of text from its standard input and prints them to its standard output with the words which are not balanced removed.

A word is balanced if every character in the word occurs exactly n times (for some value of n).

Case should be ignored when considering whether a word is balanced.

For example: Gaga is balanced because 'g' occurs twice and 'a' occurs twice.

For example: gauge is not balanced because 'g' occurs twice but 'u', 'a', and 'e' occur once.

Assume that a word is any sequence of non-whitespace characters.
For example, tock-tock is considered a single word.

You should print the words separated by a single space character.

Match the example output below exactly. For example:

cat frost.txt
I shall be telling this with a sigh
Somewhere ages and ages hence:
Two roads diverged in a wood, and I --
I took the one less traveled by,
And that has made all the difference.
./practice_q10.py < frost.txt
I be this with a sigh
ages and ages
Two roads in a and I --
I the one by,
And has made the
cat interesting_words.txt
1 duck   bulbul  Gaga    tocktocktock  wwwwweeeee
2 goose baboon bonobo   Guage tock-tock  wwwwweee
3 xerophytic   Deeded sestettes     zZz teammate horseshoer happenchance
4   elephant decorator    agaga  teammates            horseshoe
./practice_q10.py <  interesting_words.txt
1 duck bulbul Gaga tocktocktock wwwwweeeee
2
3 xerophytic Deeded sestettes zZz teammate horseshoer happenchance
4
./practice_q10.py < story.txt | head
THE LEAP-FROG

A Flea, a and a Leap-frog once wanted to
could jump and they the whole world,
and who chose to come to the
festival. famous jumpers they, as
would say, when they met in the

"I give my daughter to him who jumps
the King; "for it is not so amusing
./practice_q10.py < story.txt | tail
The Flea then went into foreign it is said,
he was

The sat on a bank, and
on things; and he said "Yes, a fine
is fine is what care
about." And then he began his peculiar
song, from we have taken this history; and may,
very be it does stand
printed in black and white.

When you think your program is working, you can run some simple automated tests:

2041 autotest practice_q10

When you are finished working on this activity, you must submit your work by running give:

give cs2041 practice_q10 practice_q10.py

To verify your submissions for this activity:

2041 classrun -check

We need a program to check if the same files are present in two directory trees.

Write a POSIX-compatible Shell script, practice_q11.sh, which is given either 2 arguments which are the pathnames of directories.

practice_q11.sh should print a single line of output containing 4 integers:

• number of files that are present at the same position in both directory trees and are the same size.
• number of files that are present at the same position in both directory trees but are different sizes.
• number of files that are present only in the first directory tree.
• number of files that are present only in the second directory tree.

For example, if we are comparing the directory trees dir1 and dir2. and the file dir1/2041/lab09/answer.py exists in the first directory tree,

We consider it present in the second directory tree only if the file dir2/2041/lab09/answer.py exists.

Other files named answer.py elsewhere in the second directory tree, e.g. dir2/2521/lab05/answer.py are not counted.

When a file is present at the same relative pathname in both directory trees practice_q11.sh does not have to check if it contains the same contents (bytes), just whether both files are the same size (same number of bytes).

For example:
these commands create 2 directory trees named d1 and d2 containing 3 files of the same name.

mkdir -p d1/b/c
echo hello andrew > d1/file1
echo bye andrew > d1/b/file2
echo 1 > d1/b/c/one
mkdir -p d2/b/c
echo HELLO andrew > d2/file1
echo Bye Andrew > d2/b/file2
echo 2 > d2/b/c/one

./practice_q11.sh d1 d2
3 0 0 0

echo hello everyone >d1/file1
./practice_q11.sh d1 d2
2 1 0 0

echo 3 > d2/b/c/three
./practice_q11.sh d1 d2
2 1 0 1

echo 3 > d1/b/three
./practice_q11.sh d1 d2
2 1 1 1

When you think your program is working, you can run some simple automated tests:

2041 autotest practice_q11

When you are finished working on this activity, you must submit your work by running give:

give cs2041 practice_q11 practice_q11.sh

To verify your submissions for this activity:

2041 classrun -check

A chessboard is an 8x8 square matrix. We label each square as below:

a8 b8 c8 d8 e8 f8 g8 h8
a7 b7 c7 d7 e7 f7 g7 h7
a6 b6 c6 d6 e6 f6 g6 h6
a5 b5 c5 d5 e5 f5 g5 h5
a4 b4 c4 d4 e4 f4 g4 h4
a3 b3 c3 d3 e3 f3 g3 h3
a2 b2 c2 d2 e2 f2 g2 h2
a1 b1 c1 d1 e1 f1 g1 h1

A knight makes an L-shaped move. It moves either two squares horizontally and one square vertically or two squares vertically and one square horizontally.

For example, a knight at d4 can move to one of eight squares: c2, e2, b3, b5, c6, e6, f3 or f5.

A move can not take a knight off the chessboard. Hence, a knight on square near the edge of the board will have fewer possible moves.

For example, a knight at a1 can move only to c2 and b3.

Your program should take one argument: a starting square.

It should print a sequence of lines.

The first line should contain only the starting square

The second line should contain squares a knight can move to from the starting square.

The third line should contain new squares a knight can move to from squares listed on the second line.

The fourth line should contain new squares a knight can move to from squares listed on the third line.

You program should stop when no new squares can be reached.

The squares on each line should be printed in sorted order, separated by a single space.

Match the output format below EXACTLY.

For example:

./practice_q12.sh a1
a1
b3 c2
a3 a5 b4 c1 c5 d2 d4 e1 e3
a2 a4 a6 b1 b5 b7 c4 c6 d1 d3 d5 d7 e2 e4 e6 f1 f3 f5 g2 g4
a7 b2 b6 b8 c3 c7 d6 d8 e5 e7 f2 f4 f6 f8 g1 g3 g5 g7 h2 h4 h6
a8 c8 e8 f7 g6 g8 h1 h3 h5 h7
h8
./practice_q12.sh d4
d4
b3 b5 c2 c6 e2 e6 f3 f5
a1 a3 a5 a7 b4 b8 c1 c3 c5 c7 d2 d6 d8 e1 e3 e5 e7 f4 f8 g1 g3 g5 g7 h2 h4 h6
a2 a4 a6 a8 b1 b7 c4 c8 d1 d3 d5 d7 e4 e8 f1 f7 g2 g4 g6 g8 h1 h3 h5 h7
b2 b6 f2 f6 h8
./practice_q12.sh g2
g2
e1 e3 f4 h4
c2 c4 d1 d3 d5 e2 e6 f1 f3 f5 g4 g6 h3 h5
a1 a3 a5 b2 b4 b6 c1 c3 c5 c7 d2 d4 d6 d8 e5 e7 f2 f6 f8 g1 g3 g5 g7 h2 h6 h8
a2 a4 a6 a8 b1 b3 b5 b7 c6 c8 d7 e4 e8 f7 g8 h1 h7
a7 b8

When you think your program is working, you can run some simple automated tests:

2041 autotest practice_q12

When you are finished working on this activity, you must submit your work by running give:

give cs2041 practice_q12 practice_q12.sh

To verify your submissions for this activity:

2041 classrun -check