Linux LPI 117-101 # 5 Of 9

1. What command returns the first few lines of a given file?

head command displays the few lines from the top of file. By default
displays 10 lines.
Example: head myfile
head -n or --lines 20 myfile

Explanation

head command displays the few lines from the top of file. By default
displays 10 lines.
Example: head myfile
head -n or --lines 20 myfile

Submit

2. To send input to both stdout AND a file, you use the _____ command.

tee command redirect output to a file while still piping it to another
program.
Example: set | tee set.out | less : In example, output from set is written to file set.out
while also being piped to less.

Explanation

tee command redirect output to a file while still piping it to another
program.
Example: set | tee set.out | less : In example, output from set is written to file set.out
while also being piped to less.

Submit

3. What command will show the last 10 lines of a file by default?

Tail

Head

Cat

Prstat

Ps

head command by default displays 10 lines from the top of file and tail
command by default display 10 lines from the bottom of file.
tail -n or --lines 20 filename : Displays 20 lines from the top of file.

Explanation

head command by default displays 10 lines from the top of file and tail
command by default display 10 lines from the bottom of file.
tail -n or --lines 20 filename : Displays 20 lines from the top of file.

4. You want to redirect the last 30 lines of a file to another file.
What single command would best fit your needs?

tail command displays the few lines from the bottom of file. By default
it displays the 10 lines.
Example
tail filename
tail -n 30 filename >anotherfilename : Redirects the last 30 lines into another file.

Explanation

tail command displays the few lines from the bottom of file. By default
it displays the 10 lines.
Example
tail filename
tail -n 30 filename >anotherfilename : Redirects the last 30 lines into another file.

Submit

5. Ýou have a text file with tab-separated values, but your application needs them
space-separated. What command would you use from the Bash shell to achieve this?
Please fill in the command only, without any options.

The expand command is used to convert from tab to space.
Example: expand -t 2 test à It will convert the tab into two spaces.

Explanation

The expand command is used to convert from tab to space.
Example: expand -t 2 test à It will convert the tab into two spaces.

Submit

6. You have a file with the following contents:
            A. allan
            B. bart
            C. ceasar
            D. alicia
            E. beatrice
            F. cecilia
What single command could you use to list the file contents in reverse order? (Include
only the command without options or arguments)

file1 contains :
a
b
c
and file2 contains
1
2
3
if you use tac file1 file2
Output is like:
c
b
a
3
2
1

Explanation

file1 contains :
a
b
c
and file2 contains
1
2
3
if you use tac file1 file2
Output is like:
c
b
a
3
2
1

Submit

7. You have a file with the following contents:
            A. allan
            B. bart
            C. ceasar
            D. alicia
            E. beatrice
            F. Cecilia
What single command could you use to list the file contents in reverse order? Please
include only the command without options or arguments.

tac command concatenate and print files in reverse order.
Example:
file1 contains :
a
b
c
and file2 contains
1
2
3
if you use tac file1 file2
Output is like:
c
b
a
3
2
1

Explanation

tac command concatenate and print files in reverse order.
Example:
file1 contains :
a
b
c
and file2 contains
1
2
3
if you use tac file1 file2
Output is like:
c
b
a
3
2
1

Submit

9. What command takes you to your home directory without using a path?

~ symbol represents the user's home directory. cd ~ command enters
into the user's home directory. Similalry cat ~/test.txt displays the contents of
test.txt resident into user's home directory.

Explanation

~ symbol represents the user's home directory. cd ~ command enters
into the user's home directory. Similalry cat ~/test.txt displays the contents of
test.txt resident into user's home directory.

Submit

10. What command will show the first 10 lines of a file by default?

Head

Cat

Tac

Nl

Tail

ead command by default displays 10 lines from the top of file and tail
command by default display 10 lines from the bottom of file.
head -n or --lines 20 filename : Displays 20 lines from the top of file.

Explanation

ead command by default displays 10 lines from the top of file and tail
command by default display 10 lines from the bottom of file.
head -n or --lines 20 filename : Displays 20 lines from the top of file.

11. What command will print a list of usernames (first column) and their
corresponding user id (uid, third column) from /etc/passwd?

Cut -d: -f 1,3 /etc/passwd

Chop -c 1,3 /etc/passwd

Tac 1-3 /etc/passwd

Fmt -u /etc/passwd

Cut command helps to display certain fields value from file. In cut
command -d option is used to specify the filed delimiter and -f specify the filed
number.

Explanation

Cut command helps to display certain fields value from file. In cut
command -d option is used to specify the filed delimiter and -f specify the filed
number.

12. You wish to move all files and directories from within /home/john to the directory
/home/certkiller.
Type in the command line that would do this?

mv command is used to move as well as to rename the file.
Example:
mv file1 file2 : Which renames the file1 to file2.
mv file1 /tmp : Which moves the file file1 into /tmp
mv file1 /tmp/file2 : Which moves as well as rename the file file1
mv /home/john/* /home/certkiller : Moves all the contents of /home/john into
/home/certkiller.

Explanation

mv command is used to move as well as to rename the file.
Example:
mv file1 file2 : Which renames the file1 to file2.
mv file1 /tmp : Which moves the file file1 into /tmp
mv file1 /tmp/file2 : Which moves as well as rename the file file1
mv /home/john/* /home/certkiller : Moves all the contents of /home/john into
/home/certkiller.

Submit

13. What switch is used with the useradd command to specify a user's initial group?

-g

-i

-u

-ig

When we create the user it creates the group same username and
make user belongs to that group as a private group. If you want to chage the private
group at user creating time:
useradd -g groupname username

Explanation

When we create the user it creates the group same username and
make user belongs to that group as a private group. If you want to chage the private
group at user creating time:
useradd -g groupname username

14. Which command is used to dump files in octal format?

Od

Octdump

Dumpoct

Cat -o

nswer A is correct. od command dump files in octal and other
formats. Example: od test it will display the all contents of file in octal format.

Explanation

nswer A is correct. od command dump files in octal and other
formats. Example: od test it will display the all contents of file in octal format.

15. You wish to copy the full contents of the /home/jack directory and all subdirectories
to the /home/bill directory.
Type in the simplest command to do this.

cp command copies files/directorires.
Syntax: rm [options] file/directory
-f : forcely
-r : Recursively
-i : Interactively.
cp -r /home/jack/* /home/bill : Which copy all the contents of /home/jack into the
/home/bill.

Explanation

cp command copies files/directorires.
Syntax: rm [options] file/directory
-f : forcely
-r : Recursively
-i : Interactively.
cp -r /home/jack/* /home/bill : Which copy all the contents of /home/jack into the
/home/bill.

Submit

16. What command will remove duplicate lines from a sorted file?

Filter

Trim

Uniq

Wc

uniq - remove duplicate lines from a sorted file

Explanation

uniq - remove duplicate lines from a sorted file

17. Type the command will identify the io address range used by a NIC?

/proc is called the virtual file system, which contains the information
about the running kernel.
/proc/ioports file contains the I/O address range being used by the network card.
When you read the file /proc/ioports :
d800-d8ff : 8139too : Where 8139too is the module of Realtek Ethernet card.

Explanation

/proc is called the virtual file system, which contains the information
about the running kernel.
/proc/ioports file contains the I/O address range being used by the network card.
When you read the file /proc/ioports :
d800-d8ff : 8139too : Where 8139too is the module of Realtek Ethernet card.

Submit

18. Which of the following commands can you use to rename a file in Linux?

N

Mv

New

Rm

mv file1 file2 : Which renames the file1 to file2.
mv file1 /tmp : Which moves the file file1 into /tmp
mv file1 /tmp/file2 : Which moves as well as rename the file file1

Explanation

mv file1 file2 : Which renames the file1 to file2.
mv file1 /tmp : Which moves the file file1 into /tmp
mv file1 /tmp/file2 : Which moves as well as rename the file file1

19. What will the command cd ~ do?

Take you to the ~ directory

Take you to the sys directory.

Take you to your home directory.

Nothing, this command is invalid.

~ symbol represents the user's home directory. cd ~ command enters
into the user's home directory. Similalry cat ~/test.txt displays the contents of
test.txt resident into user's home directory.

Explanation

~ symbol represents the user's home directory. cd ~ command enters
into the user's home directory. Similalry cat ~/test.txt displays the contents of
test.txt resident into user's home directory.

20. You want to move all files in /dir1 to /dir2 that begin with a and end with v. What is
the correct command to do this?

Mv /dir1/a*v /dir2

Mv -r /dir1/a.v /dir2

Move /dir1/a?v /dir2

Ls a*v | cp /dir2

Mv /dir1/[a-v] /dir2

Wildcard characters :
* Zero or more character
? Any Single Character
[a-z] Any Single Character from the range
[^a-z] Any Single Character except from the range
mv /dir1/a*v /dir2 means all the contents of /dir1 starting name with a character and
ended with v character will move into the /dir2 directory.

Explanation

Wildcard characters :
* Zero or more character
? Any Single Character
[a-z] Any Single Character from the range
[^a-z] Any Single Character except from the range
mv /dir1/a*v /dir2 means all the contents of /dir1 starting name with a character and
ended with v character will move into the /dir2 directory.

21. You wish to cut the 3rd and 7th fields from a colon (:) delimited text file called
'my Certkiller ' and display them on the screen. Type the command that would do this?

cut command displays the specific column from the text file.
Example: cut -d: -f 1 /etc/passwd : Displays the first column from the file /etc/passwd
where -d means delimeter and -f means field number. To display the contents of multiple
column, comma separator can use.

Explanation

cut command displays the specific column from the text file.
Example: cut -d: -f 1 /etc/passwd : Displays the first column from the file /etc/passwd
where -d means delimeter and -f means field number. To display the contents of multiple
column, comma separator can use.

Submit

22. Which command removes all subdirectories in /tmp, regardless of
whether they are non-existent or in use?

Del /tmp/*

M -rf /tmp

Rm -Ra /tmp/*

Rm -rf /tmp/*

Delete /tmp/*,*

rm command removes the files/directorires.
Syntax: rm [options] file/directory
-f : forcely
-r : Recursively
-i : Interactively.
rm -rf /tmp/* : Which removes all files as well as directories forcely from /tmp directory.

Explanation

rm command removes the files/directorires.
Syntax: rm [options] file/directory
-f : forcely
-r : Recursively
-i : Interactively.
rm -rf /tmp/* : Which removes all files as well as directories forcely from /tmp directory.

23. Which of the following would copy the file file1.txt to file2.txt?

Cp file1.txt | file2.txt

Cat file1.txt | file2.txt

Cat file1.txt > file2.txt

Copy file1.txt | file2.txt

Cat | file1.txt | file2.txt

We can redirect the standard output into the file using the redirect (>)
symbol.
Example: ls -l >result : Redirects the standard output of ls -l command into the result file.
Similarly cat redirect the contents of one file into another.
cat file1 >file2 : cat reads the contents of file1 and creates the new file file2, which
contains the text of file1.
Similarly you can append into the existing file using append (>>) symbol.

Explanation

We can redirect the standard output into the file using the redirect (>)
symbol.
Example: ls -l >result : Redirects the standard output of ls -l command into the result file.
Similarly cat redirect the contents of one file into another.
cat file1 >file2 : cat reads the contents of file1 and creates the new file file2, which
contains the text of file1.
Similarly you can append into the existing file using append (>>) symbol.

24. What command would help you identify the I/O address range being used by the
network card?

Cat /proc/modules

Cat /proc/devices

Cat /proc/meminfo

Cat /io/dma

Cat /proc/ioports

/proc is called the virtual file system, which contains the information
about the running kernel.
/proc/ioports file contains the I/O address range being used by the network card.
When you read the file /proc/ioports :
d800-d8ff : 8139too : Where 8139too is the module of Realtek Ethernet card.

Explanation

/proc is called the virtual file system, which contains the information
about the running kernel.
/proc/ioports file contains the I/O address range being used by the network card.
When you read the file /proc/ioports :
d800-d8ff : 8139too : Where 8139too is the module of Realtek Ethernet card.

25. You logged in as user linux1, but now you want to switch users to linux2 with linux's
environment. How would you do this?

Su linux2

Su -e linux2

Su - linux2

Su -m linux2

Su -f linux2

su means switch user. To switch from one user to another user with
another user's environment and home directory use - option. Here switching to
linux2 , then su - linux2 is answer.

Explanation

su means switch user. To switch from one user to another user with
another user's environment and home directory use - option. Here switching to
linux2 , then su - linux2 is answer.

26. What utility would use to remove/display columns from each line of a file?

Pwd

Col

Cut

Tail

Extract

cut command displays the specific column from the text file.
Example: cut -d: -f 1 /etc/passwd : Displays the first column from the file /etc/passwd
where -d means delimeter and -f means field number.

Explanation

cut command displays the specific column from the text file.
Example: cut -d: -f 1 /etc/passwd : Displays the first column from the file /etc/passwd
where -d means delimeter and -f means field number.

27. Which of the following will copy file1.txt to file2.txt? Choose Two.

Cat file1.txt > file2.txt

Cat file1.txt | file2.txt

Cp file1.txt > file2.txt

Cp file1.txt file2.txt

Cpio < file1.txt > file2.txt

We can redirect the standard output into the file using the redirect (>)
symbol.
Example: ls -l >result : Redirects the standard output of ls -l command into the result file.
Similarly cat redirect the contents of one file into another.
cat file1 >file2 : cat reads the contents of file1 and creates the new file file2, which
contains the text of file1. cp (copy) command also copy the file.
Similarly you can append into the existing file using append (>>) symbol.

Explanation

We can redirect the standard output into the file using the redirect (>)
symbol.
Example: ls -l >result : Redirects the standard output of ls -l command into the result file.
Similarly cat redirect the contents of one file into another.
cat file1 >file2 : cat reads the contents of file1 and creates the new file file2, which
contains the text of file1. cp (copy) command also copy the file.
Similarly you can append into the existing file using append (>>) symbol.

Submit

28. You need to display all files in the current directory that start with a "a" and end
with a "v", regardless of their length or use of delimiters. Choose the best answer.

Ls a*v

Ls a.v

Ls a-v

Ls [a-v]

Wildcard characters :
* Zero or more character
? Any Single Character
[a-z] Any Single Character from the range
[^a-z] Any Single Character except from the range
ls a*v means list all files/directories starting with a character and ended with v character.

Explanation

Wildcard characters :
* Zero or more character
? Any Single Character
[a-z] Any Single Character from the range
[^a-z] Any Single Character except from the range
ls a*v means list all files/directories starting with a character and ended with v character.

29. You had a contractor come into your company. You originally set his account to expire
after thirty days. You now need to change this. How can you do this?

Usermod -e

Usermod -a

Usermod -x

Usermod -d

To set the account expire date:
usermod -e "date" username
Example: usermod -e "May 20 2006" user1

Explanation

To set the account expire date:
usermod -e "date" username
Example: usermod -e "May 20 2006" user1

30. Your lead sysadmin has asked you to add a second NIC to a Linux machine.
Which of the following commands would be best to determine which interrupts are
currently in use on this machine?

Cat /proc/ioports

Cat /proc/interrupts

Cat /proc/memoryinfo

Which interrupts

Tail /var/log/messages

The Linux /proc Directory is a Virtual Filesystem provided by linux
kernel. /proc contains files and directories that let system administrators and
programmers access system information.
The file /proc/interrupts file contains information on interrupts and IRQs. First Ethernet
card device name is eth0, second Ethernet card device name is eth1 ..., to identify that
dev will conflict or not , see the contains of file. Already eth0 is appeared or not ?
Here is the output of /proc/interrupts
CPU0
0: 380893 XT-PIC timer
1: 843 XT-PIC i8042
2: 0 XT-PIC cascade
5: 0 XT-PIC uhci_hcd

8: 1 XT-PIC rtc
11: 48 XT-PIC Intel 82801AA-ICH, eth0
14: 6086 XT-PIC ide0
NMI: 0
ERR: 0
For a multi-processor machine, this _le may look slightly different:
CPU0 CPU1
0: 1366814704 0 XT-PIC timer
1: 128 340 IO-APIC-edge keyboard
2: 0 0 XT-PIC cascade
8: 0 1 IO-APIC-edge rtc
12: 5323 5793 IO-APIC-edge PS/2 Mouse
13: 1 0 XT-PIC fpu
16: 11184294 15940594 IO-APIC-level Intel EtherExpress Pro
10/100 Ethernet
20: 8450043 11120093 IO-APIC-level megaraid
30: 10432 10722 IO-APIC-level aic7xxx
31: 23 22 IO-APIC-level aic7xxx
NMI: 0
ERR: 0
Appeared Number of CPU, Number of Ethernet card.

Explanation

The Linux /proc Directory is a Virtual Filesystem provided by linux
kernel. /proc contains files and directories that let system administrators and
programmers access system information.
The file /proc/interrupts file contains information on interrupts and IRQs. First Ethernet
card device name is eth0, second Ethernet card device name is eth1 ..., to identify that
dev will conflict or not , see the contains of file. Already eth0 is appeared or not ?
Here is the output of /proc/interrupts
CPU0
0: 380893 XT-PIC timer
1: 843 XT-PIC i8042
2: 0 XT-PIC cascade
5: 0 XT-PIC uhci_hcd

8: 1 XT-PIC rtc
11: 48 XT-PIC Intel 82801AA-ICH, eth0
14: 6086 XT-PIC ide0
NMI: 0
ERR: 0
For a multi-processor machine, this _le may look slightly different:
CPU0 CPU1
0: 1366814704 0 XT-PIC timer
1: 128 340 IO-APIC-edge keyboard
2: 0 0 XT-PIC cascade
8: 0 1 IO-APIC-edge rtc
12: 5323 5793 IO-APIC-edge PS/2 Mouse
13: 1 0 XT-PIC fpu
16: 11184294 15940594 IO-APIC-level Intel EtherExpress Pro
10/100 Ethernet
20: 8450043 11120093 IO-APIC-level megaraid
30: 10432 10722 IO-APIC-level aic7xxx
31: 23 22 IO-APIC-level aic7xxx
NMI: 0
ERR: 0
Appeared Number of CPU, Number of Ethernet card.

31. Which of the following commands will duplicate the contents of the /A directory in
the existing and empty /B directory?

Mv /A/* /B

Mv /A/ /B

Mv /A /B

Mv /A/* .

mv command is used to move as well as to rename the file.
Example:
mv file1 file2 : Which renames the file1 to file2.
mv file1 /tmp : Which moves the file file1 into /tmp
mv file1 /tmp/file2 : Which moves as well as rename the file file1
mv /home/john/* /home/certkiller : Moves all the contents of /home/john into
/home/certkiller.

Explanation

mv command is used to move as well as to rename the file.
Example:
mv file1 file2 : Which renames the file1 to file2.
mv file1 /tmp : Which moves the file file1 into /tmp
mv file1 /tmp/file2 : Which moves as well as rename the file file1
mv /home/john/* /home/certkiller : Moves all the contents of /home/john into
/home/certkiller.

32. What option is used with the useradd command to specify the user's user id?

-u

-s

-ui

-id

By default 0-499 user id reserved for system user and starts to assign
from 500 to normal user. To set the user id at useradd command use the -u option.
Example:
useradd -u 1000 user1 : Which creates the user user1 having user id 1000.
You can display user id as well as group id using the id command

Explanation

By default 0-499 user id reserved for system user and starts to assign
from 500 to normal user. To set the user id at useradd command use the -u option.
Example:
useradd -u 1000 user1 : Which creates the user user1 having user id 1000.
You can display user id as well as group id using the id command

33. To convert all uppercase letters in stream to lowercase, pipe the stream into which

Tr A-Z a-z

Tac A-Z a-z

Sed /A-Z a-z

Sed -tolower

Conv [A-Z] [a-z]

tr command translate the characters, that is given ranges of
characters, any time a character in range 1 is found, it is translated into the
equivalent character in range 2.
Example:
tr 'a-z' 'A-Z'

Explanation

tr command translate the characters, that is given ranges of
characters, any time a character in range 1 is found, it is translated into the
equivalent character in range 2.
Example:
tr 'a-z' 'A-Z'

34. Which of the following can be used to change a user's home directory?

Usermod -d

Usermod -h

Usermod -u

Usermod -c

To change the user's home directory use the -d option in usermod
command.
Example:
usermod -d /var/user1 user1 : Which sets the home directory of user user1 into the
/var/user1.
usermod -s /bin/sh user1 : Which sets the default shell of user user1 sh shell.
usermod -L user1 : Which locks the user account
usermod -U user1 : Which unlocks the user account

Explanation

To change the user's home directory use the -d option in usermod
command.
Example:
usermod -d /var/user1 user1 : Which sets the home directory of user user1 into the
/var/user1.
usermod -s /bin/sh user1 : Which sets the default shell of user user1 sh shell.
usermod -L user1 : Which locks the user account
usermod -U user1 : Which unlocks the user account

35. Which of these commands would report how many total accounts (including special
accounts) there are?

Count /etc/passwd

Nl /etc/passwd | head

Wc --users /etc/passwd

Wc --lines /etc/passwd

Expand --lines /etc/passwd

wc command displays the number of lines, words and characters.
wc filename : prints number of lines, words and characters.
wc -l or --lines filename : prints the number of lines in file.
wc -w or --words filename : prints the number of words in file.
wc -c filename : prints the number of characters in file.

Explanation

wc command displays the number of lines, words and characters.
wc filename : prints number of lines, words and characters.
wc -l or --lines filename : prints the number of lines in file.
wc -w or --words filename : prints the number of words in file.
wc -c filename : prints the number of characters in file.

36. What is the result of the following command?
# cat 'echo "$ Certkiller

A syntax error

The value of $ Certkiller

Cat followed by the value of $ Certkiller

Echo followed by the value of $ Certkiller

Echo followed by $ Certkiller

Varaible is called the memory location containing the value. In linux
we can read the value of variable starting by $ symbol at starting of variable name.
Example: Certkiller =test.txt
echo $ Certkiller : Displays the value of variable Certkiller
cat $ Certkiller : Displays the contents of file of $ Certkiller
In QUESTION ' is started which is incorrect syntax.

Explanation

Varaible is called the memory location containing the value. In linux
we can read the value of variable starting by $ symbol at starting of variable name.
Example: Certkiller =test.txt
echo $ Certkiller : Displays the value of variable Certkiller
cat $ Certkiller : Displays the contents of file of $ Certkiller
In QUESTION ' is started which is incorrect syntax.

37. Which of the following would do the same as the command cat < file1.txt > file2.txt?

Cat < file1.txt file2.txt

Cat file1.txt >file2.txt

Cat

Cat file 1.txt | file2.txt

Cp file1.txt>file2.txt

cat file1.txt >file2.txt cat command takes input from the file file1 and
redirect the output into the file file2 which is similar to cat file2.txt.

Explanation

cat file1.txt >file2.txt cat command takes input from the file file1 and
redirect the output into the file file2 which is similar to cat file2.txt.

38. After executing the following command line, what will be the contents of the file
myout.txt?
echo \" Certkiller \" | cat > myout.txt

Certkiller

" Certkiller "

Certkiller cat

The file is empty

The contents of myout.txt will be Certkiller .
echo command displays into the standard output and cat command redirects the output of
echo into the file myout.txt

Explanation

The contents of myout.txt will be Certkiller .
echo command displays into the standard output and cat command redirects the output of
echo into the file myout.txt

39. What command will easily convert tabs in files to spaces?

Convert

Expand

Tr

Sed

None of the above

The command "expand" can be used to easily convert tabs in files to spaces.

Explanation

The command "expand" can be used to easily convert tabs in files to spaces.

40. What does the following command do?
cat '$TEST'

Displays a bash syntax error message.

Displays the contents of the file named $TEST if it exists.

Waits for the user to enter text and then echos the text back.

Displays the contents of the file named inside the back quotes.

Displays the contents of the named by the environment variable TEST.

Varaible is called the memory location containing the value. In linux
we can read the value of variable starting by $ symbol at starting of variable name.
Example: FILENAME=test.txt
echo $FILENAME : Displays the value of variable FILENAME
cat $FILENAME : Displays the contents of file of $FILENAME

Explanation

Varaible is called the memory location containing the value. In linux
we can read the value of variable starting by $ symbol at starting of variable name.
Example: FILENAME=test.txt
echo $FILENAME : Displays the value of variable FILENAME
cat $FILENAME : Displays the contents of file of $FILENAME

41. A directory contains the following files:
#ls
ratas saran jacaw cabal cabin
You issue the command "ls | grep .a[^b]a.", what files are returned by the
command? Choose all that apply.

Ratas

Jacaw

Saran

Cabal

Cabin

Remember the wildcard Character in string processing
* : Zero or more character
. : Any Single Character
[a-z] : Any single Character from the range
[^a-z] : Any single Character except from the range
ls | grep .a[^b]a. means that word having five characters, starting with any character but a
should be in second position, third position shouldn't be b and fourth character should be
a and any single character in fifth position.
grep command is use to process the string with different pattern.

Explanation

Remember the wildcard Character in string processing
* : Zero or more character
. : Any Single Character
[a-z] : Any single Character from the range
[^a-z] : Any single Character except from the range
ls | grep .a[^b]a. means that word having five characters, starting with any character but a
should be in second position, third position shouldn't be b and fourth character should be
a and any single character in fifth position.
grep command is use to process the string with different pattern.

Submit

42. You are logged in as user tux1, but now you want to switch users to tux2 with tux2's
environment. How would you do this?

Su tux2

Su -e tux2

Su - tux2

Su -m tux2

Su -f tux2

su means switch user. To switch from one user to another user with
another user's environment and home directory use - option. Here switching to tux2
, then su - tux2 is answer.

Explanation

su means switch user. To switch from one user to another user with
another user's environment and home directory use - option. Here switching to tux2
, then su - tux2 is answer.

43. What option is used with the useradd command to specify the user's login shell?

-s

-l

-u

-sh

When we create the user it assign the bash shell to user, to assign the
different shell use the -s option.
Example:
useradd -s /bin/sh user1 : which creates the user user1 by assigning the /bin/sh shell.
You can check the /etc/passwd file to check the user id, user's private group id, home
directory and login shell.

Explanation

When we create the user it assign the bash shell to user, to assign the
different shell use the -s option.
Example:
useradd -s /bin/sh user1 : which creates the user user1 by assigning the /bin/sh shell.
You can check the /etc/passwd file to check the user id, user's private group id, home
directory and login shell.

44. Which of the commands will show you only the middle 10 lines of a 30 line text file
named textfile?

Head -n 11-20 textfile

Head -n 20 textfile | tail

Tail -n 11-20

Cat textfile | pr -n 11-20

Nl -n 11-30 textfile

head command displays default 10 lines from the top of file and tail
displays the default 10 lines from the bottom of file.
To display the custom number of lines:
head -n 20 filename
To displays the contents of file from middle:
head -n 20 a | tail : displays middle 10 lines
head -n 30 a | tail : displays middle 10 lines from 20-30.

Explanation

head command displays default 10 lines from the top of file and tail
displays the default 10 lines from the bottom of file.
To display the custom number of lines:
head -n 20 filename
To displays the contents of file from middle:
head -n 20 a | tail : displays middle 10 lines
head -n 30 a | tail : displays middle 10 lines from 20-30.

45. file1 and file2 are text files in your local directory.
            file1 contains this:
            allan
            bart
            ceasar
            file2 contains this:
            alicia
            beatrice
            Cecilia
            What would the output of the following command be?
            tac file1 file2

Allan/ bart/ ceasar/ alicia/ beatrice/ cecilia

Alicia/ beatrice/ cecilia/ allan/ bart/ ceasar

Alicia/ beatrice/ cecilia/ ceasar/ bart/ allan

Cecilia/ beatrice/ alicia/ ceasar/ bart/ allan

Ceasar/ bart/ allan/ cecilia/ beatrice/ alicia

tac command concatenate and print files in reverse order.
Example:
file1 contains :
a
b
c
and file2 contains
1
2
3
if you use tac file1 file2
Output is like:
c
b
a
3
2
1

Explanation

tac command concatenate and print files in reverse order.
Example:
file1 contains :
a
b
c
and file2 contains
1
2
3
if you use tac file1 file2
Output is like:
c
b
a
3
2
1

46. What dose the command cd~foo do?

It will take you to the ~foo directory.

It will create the foo directory and change to it

It will take you to the home directory of the user "foo"

It will change the directory to the system foo directory.

It will change to the foo directory in your home directory.

~ symbol represents the user's home directory.
Example: cat ~/test.txt : Which reads the file resident in user's home directory.
cd ~/foo : Which enters into the foo directory resident into the user's home directory.

Explanation

~ symbol represents the user's home directory.
Example: cat ~/test.txt : Which reads the file resident in user's home directory.
cd ~/foo : Which enters into the foo directory resident into the user's home directory.

47. As root you have navigated to directory /B. You wish to move all of the files and
directories from directory /A to directory /B. Which of the following options would
be the most appropriate command line to execute this task?

Cp /a/*

Mv -f /A/* .

Mv -Rf /a/* .

Cp -f /a/* ..

Cp -rf /A/* /b/

mv command is used to move as well as to rename the file.
Example:
mv file1 file2 : Which renames the file1 to file2.
mv file1 /tmp : Which moves the file file1 into /tmp
mv file1 /tmp/file2 : Which moves as well as rename the file file1
-f option of mv command is used for forcely move.

Explanation

mv command is used to move as well as to rename the file.
Example:
mv file1 file2 : Which renames the file1 to file2.
mv file1 /tmp : Which moves the file file1 into /tmp
mv file1 /tmp/file2 : Which moves as well as rename the file file1
-f option of mv command is used for forcely move.

48. Which line below would count the total number of lines with the word " Certkiller " in
/var/log/maillog?

Wc -l ' Certkiller /var/log/maillog'

For " Certkiller " in [maillog (count) +1]

Wc -l /var/log/maillog | grep ' Certkiller '

Cat /var/log/maillog | grep ' Certkiller ' | wc -l

Cat /var/log/mailog | grep ' Certkiller ' | wc -r

grep command displays the lines matching the criteria.
Example: grep root /etc/passwd : displays all lines having root pattern.
Wc command counts the lines, words and characters into the file.
Example: wc filename : displays number of lines, words and characters
wc -l filename : displays only the number of lines from the file.
Were Pipe symbol helps to combine the command, which sends the output of first
command as input to second command.
Answer D is correct because cat reads the contents of /var/log/maillog and sends the
standard output to grep command, g rep command filters the output only the lines having
Certkiller pattern sends to wc which counts the number of lines containing the Certkiller
pattern.

Explanation

grep command displays the lines matching the criteria.
Example: grep root /etc/passwd : displays all lines having root pattern.
Wc command counts the lines, words and characters into the file.
Example: wc filename : displays number of lines, words and characters
wc -l filename : displays only the number of lines from the file.
Were Pipe symbol helps to combine the command, which sends the output of first
command as input to second command.
Answer D is correct because cat reads the contents of /var/log/maillog and sends the
standard output to grep command, g rep command filters the output only the lines having
Certkiller pattern sends to wc which counts the number of lines containing the Certkiller
pattern.

49. You need to create a simple hierarchy of directories:
images/photos/summer/ottawa/. None of the directories on that path exists. What
command will create all of the needed directories in one step?

Mkdir -r images/photos/summer/ottawa/

Mkdir -R images/photos/summer/ottawa/

Mkdir -p images/photos/summer/ottawa/

Mkdir -P images/photos/summer/ottawa/

Mkdir -m images/photos/summer/ottawa/

-p options means no error if existing, make parent directories as
needed. It will creates the directory images/photos/summer/Ottawa. Where images
is the parent directory of photos, photos is the parent directory of summer etc.

Explanation

-p options means no error if existing, make parent directories as
needed. It will creates the directory images/photos/summer/Ottawa. Where images
is the parent directory of photos, photos is the parent directory of summer etc.

50. You enter the command date +%M. Wat does the output show you?

The current year

The current month

The current hour

The current minute

The current second

date command displays the current date and time information as well
as we can set new date and time to system by supplying -s option.
To display time: date +%T
To display Minute: date +%M
To display Month : date +%m
%% a literal %
%a locale's abbreviated weekday name (Sun..Sat)
%A locale's full weekday name, variable length (Sunday..Saturday)
%b locale's abbreviated month name (Jan..Dec)
%B locale's full month name, variable length (January..December)
%c locale's date and time (Sat Nov 04 12:02:33 EST 1989)
%C century (year divided by 100 and truncated to an integer)
[00-99]
%d day of month (01..31)
%D date (mm/dd/yy)
%e day of month, blank padded ( 1..31)
%F same as %Y-%m-%d
%g the 2-digit year corresponding to the %V week number
%G the 4-digit year corresponding to the %V week number
%h same as %b
%H hour (00..23)
%I hour (01..12)
%j day of year (001..366)
%k hour ( 0..23)
%l hour ( 1..12)
%m month (01..12)
%M minute (00..59)
%n a newline
%N nanoseconds (000000000..999999999)
%p locale's upper case AM or PM indicator (blank in many locales)
%P locale's lower case am or pm indicator (blank in many locales)
%r time, 12-hour (hh:mm:ss [AP]M)
%R time, 24-hour (hh:mm)
% seconds since a 00:00:00 1970-01-01 UTCa (a GNU extension)
%S second (00..60); the 60 is necessary to accommodate a leap sec-
ond
%t a horizontal tab
%T time, 24-hour (hh:mm:ss)
%u day of week (1..7); 1 represents Monday
%U week number of year with Sunday as first day of week (00..53)
%V week number of year with Monday as first day of week (01..53)
%w day of week (0..6); 0 represents Sunday
%W week number of year with Monday as first day of week (00..53)
%x locale's date representation (mm/dd/yy)
%X locale's time representation (%H:%M:%S)
%y last two digits of year (00..99)
%Y year (1970...)
%z RFC-2822 style numeric timezone (-0500) (a nonstandard extension)
%Z time zone (e.g., EDT), or nothing if no time zone is determinable

Explanation

date command displays the current date and time information as well
as we can set new date and time to system by supplying -s option.
To display time: date +%T
To display Minute: date +%M
To display Month : date +%m
%% a literal %
%a locale's abbreviated weekday name (Sun..Sat)
%A locale's full weekday name, variable length (Sunday..Saturday)
%b locale's abbreviated month name (Jan..Dec)
%B locale's full month name, variable length (January..December)
%c locale's date and time (Sat Nov 04 12:02:33 EST 1989)
%C century (year divided by 100 and truncated to an integer)
[00-99]
%d day of month (01..31)
%D date (mm/dd/yy)
%e day of month, blank padded ( 1..31)
%F same as %Y-%m-%d
%g the 2-digit year corresponding to the %V week number
%G the 4-digit year corresponding to the %V week number
%h same as %b
%H hour (00..23)
%I hour (01..12)
%j day of year (001..366)
%k hour ( 0..23)
%l hour ( 1..12)
%m month (01..12)
%M minute (00..59)
%n a newline
%N nanoseconds (000000000..999999999)
%p locale's upper case AM or PM indicator (blank in many locales)
%P locale's lower case am or pm indicator (blank in many locales)
%r time, 12-hour (hh:mm:ss [AP]M)
%R time, 24-hour (hh:mm)
% seconds since a 00:00:00 1970-01-01 UTCa (a GNU extension)
%S second (00..60); the 60 is necessary to accommodate a leap sec-
ond
%t a horizontal tab
%T time, 24-hour (hh:mm:ss)
%u day of week (1..7); 1 represents Monday
%U week number of year with Sunday as first day of week (00..53)
%V week number of year with Monday as first day of week (01..53)
%w day of week (0..6); 0 represents Sunday
%W week number of year with Monday as first day of week (00..53)
%x locale's date representation (mm/dd/yy)
%X locale's time representation (%H:%M:%S)
%y last two digits of year (00..99)
%Y year (1970...)
%z RFC-2822 style numeric timezone (-0500) (a nonstandard extension)
%Z time zone (e.g., EDT), or nothing if no time zone is determinable

51. One of the lines in the output from the command 'ls -l/home/pomes' is:
drwxrwsr-x 3 devel poms 1024 Oct 22 16:28 foo
The output from the command groups bubba is:
bubba : bubba poms acts
If user bubba executes the command touch/home/poms/foo/bar, which TWO of the
following must be true?

The group for /home/poms/foo/bar will be poms.

The owner for /home/poms/foo/bar will be devel

The owner for /home/poms/foo/bar will be bubba.

The group for /home/poms/foo/bar will be bubba.

The permissions for /home/poms/foo/bar will allow group read.

See carefully on output that, SGID bit is set on directory and group
owner of that directory is poms. When SGID bit is set on directory, automatically
all new creating files/directories group owner is same as parent directory means
same as foo.
To set the SGID bit:
chmod g+s directory
To Remove the SGID bit:
chmod g-s directory
So, when bubba user executes the touch /home/poms/foo/bar the group owner
automatically poms and owner user is that user who executed the command means
bubba.

Explanation

See carefully on output that, SGID bit is set on directory and group
owner of that directory is poms. When SGID bit is set on directory, automatically
all new creating files/directories group owner is same as parent directory means
same as foo.
To set the SGID bit:
chmod g+s directory
To Remove the SGID bit:
chmod g-s directory
So, when bubba user executes the touch /home/poms/foo/bar the group owner
automatically poms and owner user is that user who executed the command means
bubba.

Submit

52. What command will remove all files named core in the home directories of users
(/home), that are more than 7 days old? Type in the simplest command that would
do this, without any prompting to delete the files.

To search the files or directories, we use the find or locate command
where locate command search on it's database but faster than find command. find
command searches the files/directories in different condition but accurate than
locate command.
Syntax for find command:
find path condition action
Example: find /etc -name passwd : Search files or directories in /etc named passwd.
Similarly you can use other options:
-atime : Access Time
-mtime : Modified Time
-ctime : Change Time
-name or -iname : According to file name
-type : According to file type
Action in find command can start from -exec command.
Example: find /tmp -type f -exec rm {} \; : Which search all normal files and remove it.
find /home -mtime +7 -name core -exec rm -f {} \; : Which searches files named core
more than 7 days old and removes that file.

Explanation

To search the files or directories, we use the find or locate command
where locate command search on it's database but faster than find command. find
command searches the files/directories in different condition but accurate than
locate command.
Syntax for find command:
find path condition action
Example: find /etc -name passwd : Search files or directories in /etc named passwd.
Similarly you can use other options:
-atime : Access Time
-mtime : Modified Time
-ctime : Change Time
-name or -iname : According to file name
-type : According to file type
Action in find command can start from -exec command.
Example: find /tmp -type f -exec rm {} \; : Which search all normal files and remove it.
find /home -mtime +7 -name core -exec rm -f {} \; : Which searches files named core
more than 7 days old and removes that file.

Submit

53. Which of the following command would most likely be used to output a file in
reverse? Choose TWO correct answers.

Tac

Pr

Rev

Sed

Back

file1 contains :
a
b
c
and file2 contains
1
2
3
if you use tac file1 file2
Output is like:
c
b
a
3
2
1
pr command reformat the text for printing.

Explanation

file1 contains :
a
b
c
and file2 contains
1
2
3
if you use tac file1 file2
Output is like:
c
b
a
3
2
1
pr command reformat the text for printing.

Submit

54. To prevent a command run as root from sending both standard out (stdout) and
standard error (stderr) to any terminal or other file or device, which of the
following strings should be appended to the command?

>/dev/null

>/dev/null 1>&2

>/dev/null 2>&1

1>&2 >/dev/null

2>&1 >/dev/null

Command> file à Redirect the standard Output to file.
Command>>file à Append the standard output to file.
Command Command 2>file à Redirect the standard error to file.
Command 2>>file àAppend the Standard Error to file.

Explanation

Command> file à Redirect the standard Output to file.
Command>>file à Append the standard output to file.
Command Command 2>file à Redirect the standard error to file.
Command 2>>file àAppend the Standard Error to file.

55. Which of the following sed commands will replace all instances of the
string foo with the string foobar changing the file file1.txt in place?

Sed 's/foo/foobar/g' file1.txt

Sed 's/foo/foobar/g' file1.txt > file1.txt

Sed 's/foo/foobar/g' file1.txt | file1.txt

Sed -i 's/foo/foobar/g' file1.txt

Sed -i 's/foo/foobar/g' file1.txt > file1.txt

ed called Stream Editor, usually used to search and replace the string pattern in
file.
Syntax: sed 's/whattofind/replacewith/globally' filename
Example: sed 's/cat/dog/g' test àIt will replace all cat occurance to dog fron test file.

Explanation

ed called Stream Editor, usually used to search and replace the string pattern in
file.
Syntax: sed 's/whattofind/replacewith/globally' filename
Example: sed 's/cat/dog/g' test àIt will replace all cat occurance to dog fron test file.

56. You need to replace all instances of the word Certkiller with Certkiller in a file called
file.txt, and send the output to a file named Certkiller .txt. Type the simplest command
string to accomplish this.

sed also called the stream editor, generally use for find and replace.
sed 's/ Certkiller / Certkiller /g' file.txt > Certkiller .txt means search the Certkiller and
replace into Certkiller globally and redirects the replced output into Certkiller .txt file.

Explanation

sed also called the stream editor, generally use for find and replace.
sed 's/ Certkiller / Certkiller /g' file.txt > Certkiller .txt means search the Certkiller and
replace into Certkiller globally and redirects the replced output into Certkiller .txt file.

Submit

57. To change all lower case characters in a file to upper case, pick the correct
command. Select all that apply.

Tr 'a-z' 'A-Z' file

Tr [a-z] [A-Z] < file

Tr "a-z" "A-Z" file

Tr 'a-z' 'A-Z' < file

Tr {a-z} {A-Z} > file

tr command is used to translate the character.
Example: tr 'a-z' 'A-Z' and displays in standard output but no effect into the original file. So, B and D both
answer are correct.

Explanation

tr command is used to translate the character.
Example: tr 'a-z' 'A-Z' and displays in standard output but no effect into the original file. So, B and D both
answer are correct.

Submit