Quiz digest

Question 1

what does the host command do?

Answer 1

Lookup A, AAAA, and MX records of a domain,
or reverse DNS lookup

very similar to nslookup and dig

Question 2

what does the dmesg command do?

Answer 2

displays the contents of the kernel ring buffer

It may not display older info because it is overwritten by newer info and stored in RAM

Question 3

What command generated the following output?

21:04:15 up 14 days, 7:43, 3 users, load average : 0.89, 1.00 0.99

Answer 3

uptime

(or w)

Question 4

What command generated the following output?

Filesystem Size Used Avail Use% Mounted on
/dev/mapper 25G 20G 3.6G 85% /
/vg_ssd-root

Answer 4

df -h

Question 5

What command generated the following output?

1.8M /tmp

Answer 5

du -h

Question 6

What command generated the following output?

total used free shared buff/cache available
Mem : 9113232 3546 54522 463621 99385113

Answer 6

free

Question 7

What directory must be mounted with read and write access if it resides on its own dedicated filesystem?

Answer 7

/var

Question 8

What is the return value of a shell script after successful execution?

Answer 8

0

Question 9

What is the return value of a shell script after a failed execution?

Answer 9

any number 1 - 255

Question 10

What is Dovecot

Answer 10

Mail server like Postfix

Question 11

What is the PATH environment variable?

How do you display it?

Answer 11

ordered list of paths that Linux will search for executables when running a command

echo $PATH

Question 12

perform a case-insensitive search with line numbers

Answer 12

grep -in

Question 13

What command extracts the contents of a tar archive?

Answer 13

tar -x

Question 14

What command creates an archive file work.tar from the contents of the directory ./work/?

Answer 14

tar cf work.tar ./work/

Question 15

Where does Linux stores most of its log files in the directory tree?

Answer 15

/var/log

Question 16

Where are configuration files stored?

Answer 16

/etc

Question 17

What command would you use to create a symbolic link in Linux?

Answer 17

To create a soft link from the shell, you should use
ln -s <original_file> <link_created>
The soft link is essentially a pointer to the original file, and when the original file is deleted, the soft link does not point to anything, so “no such file or directory” is reported.</link_created></original_file>

Question 18

What does the command ‘last’ show?

Answer 18

recent user login times, tty line used, current status

Question 19

How do you view a running processes’ PID?

Answer 19

ps

Question 20

Default zip compression level?

Answer 20

6

Question 21

What is a sticky bit?

Answer 21

flag that ensures only the the owner can rename or delete a file.

——–t

Question 22

Identify each of these:

–s–s–t

Answer 22

SUID
SGID
Sticky Bit

Question 23

4
u+s

Answer 23

SUID

Question 24

2
g+s

Answer 24

SGID

Question 25

SUID + SGID

Answer 25

6 ug

Question 26

Tells Linux to run the program with the permissions of whoever owns the file rather than the user who runs the program

Answer 26

SUID --s------

Question 27

Sets the group of the running program to the group of the file

Answer 27

SGID -----s---

Question 28

view free disk space?

Answer 28

du

Question 29

How do you view the kernel version?

Answer 29

uname -r

Question 30

what command views kernel ring buffer?

Answer 30

dmesg

Question 31

/proc/ contains what?

Answer 31

one directory per process

Question 32

where is GID - group name mapping stored?

Answer 32

/etc/group

Question 33

what is a symbolic link? How do you create one?

Answer 33

they point to the path of another file. If you delete the target file the link points to the link will still exist, but it “stops working”, as it now points to “nothing”. ln -s targetfile linkname

Question 34

what is a hard link? How do you create one?

Answer 34

An additional entry in the file system pointing to the same place (inode) on the disk. Can be moved freely within the same filesystem but doesn't work across them. ln targetfile linkname

Question 35

which directory stores most of the documentation and example configurations (basically manual pages).

Answer 35

/usr/share/doc/

Question 36

command that can delete non empty directory

Answer 36

rm -r

Question 37

Which two tar options control compression?

Answer 37

-z -j

Question 38

How do you create a tar archive?

Answer 38

tar cf targetfile /destination/ The c option instructs tar to create a new archive file and the f option is the name of the file to create.

Question 39

How do you zip files?

Answer 39

zip desiredfilename *.txt

Question 40

How do you extract an archrive?

Answer 40

tar -x

Question 41

How do you decompress a file or tarball?

Answer 41

unzip filename for tarball: tar -xz

Question 42

chown syntax?

Answer 42

chown username:groupname filename