Day 2

Review of ITSK1601 – Intro Unix.

Break up into Cousin groups• Each cousin group will work as a team.

• Each team will need 5 blank sheets of paper.

• Be sure to write both cousins names at the top of each sheet of paper

• We will see 10 questions per round. Write your teams answers for all 10 questions on one page.– No late submissions of answers.– Only readable answers will be considered for credit.

10 pts extra credit possible.• You are working for 10 points of extra credit on the

first quiz.– If you get 50/50 questions correct, you would have 10 pts

added to your score on the first quiz.– 45/50 would get you 9 points.– 40/50 would get you 8 points– 35/50 would get you 7 points– 30/50 would get you 6 points– ……– 5/50 would get you 1 point.

Rules• While discussing your answer with your cousin, be

quiet so other teams cannot hear your answer.• No partial credit will be given for partially correct

answers. You gotta get it right.• Answer must be readable• You may use any notes/books/computer you want

during the game.• A correct answer may require the options which

would be passed to the command as well as the actual command.

• Judges (I.e. my) decision is final.

Round 1

Question 1• What UNIX command will show you help

information on a command?

Question 2• What UNIX command will show you a list of files

in the current directory?

Question 3• What UNIX command will show allow you to make

a copy of a file?

Question 4• What UNIX command will allow you change what

directory you are currently in?

Question 5• What UNIX command will change your current

directory to be one directory back from where you currently are?– e.g. You are currently in homeworks/hw1/answers. What

command would take you to homeworks/hw1

Question 6• What UNIX command will tell you the current

time?

Question 7• What UNIX command will show you the contents

of a file without stopping at each screen full? – I.e. What command dumps an entire file to the screen.

Question 8• What 2 UNIX commands will show you the

contents of a file but will stop at each screen full?

Question 9• What UNIX command is used to rename a file?

Question 10• What UNIX command is used to see the first 10

lines in a file?

Round 1

Answers

Question 1• What UNIX command will show you help

information on a command?

• man

Question 2• What UNIX command will show you a list of files

in the current directory?

• ls

Question 3• What UNIX command will show allow you to make

a copy of a file?

• cp

Question 4• What UNIX command will allow you change what

directory you are currently in?

• cd

Question 5• What UNIX command will change your current

directory to be one directory back from where you currently are?– e.g. You are currently in homeworks/hw1/answers. What

command would take you to homeworks/hw1

• cd ..

Question 6• What UNIX command will tell you the current

time?

• date

Question 7• What UNIX command will show you the contents

of a file without stopping at each screen full? – I.e. What command dumps an entire file to the screen.

• cat

Question 8• What 2 UNIX commands will show you the

contents of a file but will stop at each screen full?

• more and less

Question 9• What UNIX command is used to rename a file?

• mv

Question 10• What UNIX command is used to see the first 10

lines in a file?

• head

Round 2

Question 1• What UNIX command will allow you to make a

directory called Enda

Question 2• What UNIX command will remove a directory

called Enda. You can assume the directory is in the current directory and is already empty

Question 3• What UNIX command will delete the file called

Bob. You can assume Bob is in the current directory

Question 4• What UNIX command will tell you how many

words are in a file?

Question 5• What UNIX command will allow you to run an

interactive chat session with another user on your system?

Question 6• What UNIX command will show you what the user

enda is currently doing? I.e. what commands they are currently running. Assume you are not enda.

Question 7• What UNIX command will show you the

differences between the file 1.txt and 2.txt.

Question 8• What UNIX command will show you a calendar for

the month of May, 2001?

Question 9• What UNIX command repeats some text to the

screen?

Question 10• What UNIX command is used to view electronic

email?– There is more than 1 correct answer here.

Round 2

Answers

Question 1• What UNIX command will allow you to make a

directory called Enda

• mkdir Enda

Question 2• What UNIX command will remove a directory

called Enda. You can assume the directory is in the current directory and is already empty

• rmdir Enda

Question 3• What UNIX command will delete the file called

Bob. You can assume Bob is in the current directory

• rm Bob

Question 4• What UNIX command will tell you how many

words are in a file?

• wc –w <filename>

• I’ll accept just wc

Question 5• What UNIX command will allow you to run an

interactive chat session with another user on your system?

• talk

Question 6• What UNIX command will show you what the user

enda is currently doing? I.e. what commands they are currently running. Assume you are not enda.

• w enda

Question 7• What UNIX command will show you the

differences between the file 1.txt and 2.txt.

• diff 1.txt 2.txt

Question 8• What UNIX command will show you a calendar for

the month of May, 2001?

• cal 5 2001

Question 9• What UNIX command repeats some text to the

screen?

• echo

Question 10• What UNIX command is used to view electronic

email?– There is more than 1 correct answer here.

• pine

• elm

• mail

Round 3

Question 1• What EXACT UNIX command will delete the

directory homeworks and all files/subdirectories contained within.– You can assume homeworks is located in your current

directory

Question 2• What exact UNIX command will move all files in

the current directory who’s name begins with tex to the directory tex-files.– You may assume tex-files already exists, and is located

in the current directory

Question 3• What exact UNIX command would delete any file

which has a x in its file name, in this directory or any sub directory?

Question 4• What UNIX command will take the first 23 lines of

every file in the current directory and put them into a new file called first-lines.

Question 5• What UNIX command will make the file public.txt

readable to everyone on the system?– You may assume the file is in your current directory

Question 6• Assume you have a file (x.txt) which looks like this:

27 chocolate

32 mint

33 orange

99 lemon

100coffee

• What command would return the file showing the items sorted numerically ascending by the number at the front of each line

Question 7• 2 different people need to be able to edit the same

file. The file is currently located in /files/a.txt.

• Each user should see the file in their home directory.

• If either user edits their file, they should be editing the actual file /files/a.txt

• What Unix command would you need to type in each users home directory to make this true?

Question 8• What Unix command would allow you to search for

all occurances of the text Edna and replace it with the Enda in the file mylife.txt

Question 9• What SINGLE Unix command would show you any

messages in the logfile which contain either the words kernel or the IP address 10.1.1.1– The messages file is located in /var/log/message

Question 10• What SINGLE Unix command would find only

lines in /var/log/messages which contain kernel AND 10.1.1.1

Round 3

Answers

Question 1• What EXACT UNIX command will delete the

directory homeworks and all files/subdirectories contained within.– You can assume homeworks is located in your current

directory

• rm –r homeworks

Question 2• What exact UNIX command will move all files in

the current directory who’s name begins with tex to the directory tex-files.– You may assume tex-files already exists, and is located

in the current directory

• mv tex* tex-files

Question 3• What exact UNIX command would delete any file

which has a x in its file name, in this directory or any sub directory?

• rm –r *x*

Question 4• What UNIX command will take the first 23 lines of

every file in the current directory and put them into a new file called first-lines.

• head –23 * > first-lines

Question 5• What UNIX command will make the file public.txt

readable to everyone on the system?– You may assume the file is in your current directory

• chmod a+r public.txt

Question 6• Assume you have a file (x.txt) which looks like this:

27 chocolate

32 mint

33 orange

99 lemon

100coffee

• What command would return the file showing the items sorted numerically ascending by the number at the front of each line

• sort –n x.txt

Question 7• 2 different people need to be able to edit the same

file. The file is currently located in /files/a.txt.

• Each user should see the file in their home directory.

• If either user edits their file, they should be editing the actual file /files/a.txt

• What Unix command would you need to type in each users home directory to make this true?

• ln (-s) /files/a.txt .

Question 8• What Unix command would allow you to search for

all occurances of the text Edna and replace it with the Enda in the file mylife.txt

• sed s/Edna/Enda/g mylife.txt

Question 9• What SINGLE Unix command would show you any

messages in the logfile which contain either the words kernel or the IP address 10.1.1.1– The messages file is located in /var/log/message

• egrep ‘kernel|10.1.1.1’ /var/log/messages

Question 10• What SINGLE Unix command would find only

lines in /var/log/messages which contain kernel AND 10.1.1.1

• grep kernel /var/log/messages | grep 10.1.1.1

Round 4

Question 1• Imagine you have a directory with the following

permissions:

• Can users who are a member of the group managers see a list of all files in that directory?– Why? Why Not?

drwx--x--x 2 enda users 4096 Mar 21 13:06 scripts

Question 2• If you have a file called important.txt and you want

to make sure that you cannot delete it. How can you change its permissions to help prevent this?

Question 3• How could you use the command who to find out a

list of all users who are currently logged on. – Show no additional information other than username– Ensure that each username is only output once even if

they are logged in multiple times

Question 4• What UNIX command will look for any the word

Enda in the file stuff.txt– Be sure you look for enda, Enda, ENDA etc.– Be sure you do not return words like calENDAr.

Question 5• What UNIX command would count how many

times the user enda logged in on May 14.– Use the last command to find this information.– Be sure you only look for enda’s information– Be sure you only look for entries on May 14.

Question 6• What SINGLE Unix command can you use to

make the following directory:– /home/enda/1/2/3/4/5/6/7/8/9– You may assume you are currently in /home/enda– None of the sub directories exist.

• I.e. Right now, in /home/enda there is now directory called 1.

Question 7• You have a file which contains a bunch of words.

– One word per line

• You want to see all words which begin with the letter c, but you need them in REVERSE alphabetical order.– Thus you should get:

• czar• cyclone• cutoff• count• club• cat

Question 8• What Unix command would append a copy of the

file 2.txt to the end of the file 1.txt?

Question 9• Imagine you only have the cat command, and the

ability to redirect

• You start with a file that has 10 lines in it.

• What is the least number of commands you could use to make a file with 1000+ lines in it?

• What command would you be running?

Question 10• Assume you are in vi in escape [command] mode

– How would you do each of the following in a single command:

a. Delete the next 100 lines

b. Add 10 blank lines beneath the current line

c. Find the next occurrence of the word Fido in the document

d. Find the matching close } to this open {.You can assume your cursor is on top of the { for this one.

Round 4

Answers

Question 1• Imagine you have a directory with the following

permissions:

• Can users who are a member of the group managers see a list of all files in that directory?– Why? Why Not?

• Nope, you require read permission ls in a directory, for Others, no read permission exists.

drwxr-x--x 2 enda users 4096 Mar 21 13:06 scripts

Question 2• If you have a file called important.txt and you want

to make sure that you cannot delete it. How can you change its permissions to help prevent this?

• chmod u-w file

Question 3• How could you use the command who to find out a

list of all users who are currently logged on. – Show no additional information other than username– Ensure that each username is only output once even if

they are logged in multiple times

• who | awk ‘{print $1}’ | sort | uniq

Question 4• What UNIX command will look for any the word

Enda in the file stuff.txt– Be sure you look for enda, Enda, ENDA etc.– Be sure you do not return words like calENDAr.

• grep –i ^enda$ stuff.txt

Question 5• What UNIX command would count how many

times the user enda logged in on May 14.– Use the last command to find this information.– Be sure you only look for enda’s information– Be sure you only look for entries on May 14.

• last | grep “May 14” | grep enda | wc -l

Question 6• What SINGLE Unix command can you use to

make the following directory:– /home/enda/1/2/3/4/5/6/7/8/9– You may assume you are currently in /home/enda– None of the sub directories exist.

• I.e. Right now, in /home/enda there is now directory called 1.

• mkdir –p /home/enda/1/2/3/4/5/6/7/8/9

Question 7• You have a file which contains a bunch of words.

– One word per line

• You want to see all words which begin with the letter c, but you need them in REVERSE alphabetical order.– Thus you should get:

• czar

• cyclone

• cutoff

• count

• club

• cat

• grep c file | sort –r

Question 8• What Unix command would append a copy of the

file 2.txt to the end of the file 1.txt?

• cat 2.txt >> 1.txt

Question 9• Imagine you only have the cat command, and the

ability to redirect

• You start with a file that has 10 lines in it.

• What is the least number of commands you could use to make a file with 1000+ lines in it?

• What command would you be running?

• cat file >> file

• Repeat 7 times, to get 1280 lines

Question 10• Assume you are in vi in escape [command] mode

– How would you do each of the following in a single command:

a. Delete the next 100 linesb. Add 10 blank lines beneath the current linec. Find the next occurrence of the word Fido in the documentd. Find the matching close } to this open {.

You can assume your cursor is on top of the { for this one.

• a. 100d• b. 10o• c. /Fido• d. %

Round 5

Question 1• What single command will send 100 messages with

the word “Yo” to the user enda’s screen?

Question 2• Write a simple script which will output “Yes” if

enda is currently logged in and “No” if he is not.

Question 3• What Unix command would give you the answer to

the following math problem:

• (100 * 50) / 5

Question 4• Imagine you have a file called users with a list of

user names in it.– Write a simple script which one at a time will check if

that user is logged on, if they are send them the message “Hey”

Question 5• Write a script which when run, decides what season

it is. And tells you.– For simplicity lets assume the following:– Winter: Dec, Jan, Feb– Spring: Mar, Apr, May– Summer: Jun, Jul, Aug– Fall: Sep, Oct, Nov

Question 6• Write a script which renames the files

– 1.txt, 2.txt, 3.txt

• To the new name:– file1.txt, file2.txt, file3.txt

• The script should do this for all files up to 22.txt

• Be sure the user never sees any errors even if a given file (17.txt) doesn’t exist.

• Use a loop.

Question 7• Write a script which takes one parameter, a file

name.– If the file exists

• Show us the file using more

– Otherwise• Give an error “I could not open you file called xxx”

• Be sure xxx is replaced with the actual file the user typed.

Round 5

Answers

Question 1• What single command will send 100 messages with

the word “Yo” to the user enda’s screen?

let x=0

while [ $x –lt 100 ]

doecho “Yo” | write enda

let x=$x+1

done

Question 2• Write a simple script which will output “Yes” if

enda is currently logged in and “No” if he is not.

if who | grep enda

then

echo “Yes”

else

echo “No”

fi

Question 3• What Unix commands would give you the answer to

the following math problem:

• (100 * 50) / 5

let x=(100*50)/5

echo $x

Question 4• Imagine you have a file called users with a list of user

names in it.– Write a simple script which one at a time will check if that user is

logged on, if they are send them the message “Hey”

for name in `cat users`

do

if who | grep $name

then

echo “hey” | write $name

fi

done

Question 5• Write a script which when run, decides what season it is.

And tells you.– For simplicity lets assume the following:

– Winter: Dec, Jan, Feb

– Spring: Mar, Apr, May

– Summer: Jun, Jul, Aug

– Fall: Sep, Oct, Nov

• if date | grep –i dec –o date | grep –i jan –o date | grep feb• then• echo “Winter”• elif date | grep –i mar –r date | grep –i Apr …

Question 6• Write a script which renames the files

– 1.txt, 2.txt, 3.txt

• To the new name:– file1.txt, file2.txt, file3.txt

• The script should do this for all files up to 22.txt• Be sure the user never sees any errors even if a given file (17.txt) doesn’t exist.• Use a loop.

let x=1while [ $x –lt 22 ]do mv $x.txt file$x.txt 2> /dev/null let x=$x+1done

Question 7• Write a script which takes one parameter, a file name.

– If the file exists• Show us the file using more

– Otherwise• Give an error “I could not open your file called xxx”

• Be sure xxx is replaced with the actual file the user typed.

if [ -f $0 ]then more $0else echo “I could not open your file called $0”fi