Basic Commands

Question 1

Runlevel

Answer 1

-determines which level machine is running on

Question 2

Init 0-6

Answer 2

-whole server action

0 - Halt (sleep mode)
1 - Single-user mode (safe)
2 - Multi-user mode w/out networking
$3 - Multi-user mode w/ networking$
4 - NO FUNCTION 
5 - Graphic User Interface (GUI)
6 - Reboot

Question 3

Chkconfig

Answer 3

• sees all services running
• Chkconfig (service) on/off (turns service on/off at startup)
• Chkconfig | grep service (checks particular run levels of service)
• Chkconfig –level (run level[s]) on/off (turns particular run levels on/off for selected service)

Question 4

Fg

Answer 4

-brings the most recent job to foreground

Question 5

bg

Answer 5

-lists stopped or background jobs; resumes a stopped job in the background

Question 6

Ln -s FILE LINK

Answer 6

-create a symbolic LINK to FILE

Question 7

Pwd

Answer 7

-show current directory

Question 8

Ls -al

Answer 8

-formatted listings w/ hidden files

Question 9

gzip -d FILE.gz

Answer 9

-decompressed FILE.gz back to FILE

Question 10

Ctrl +r

Answer 10

-bring up a recent command

Question 11

Ctrl +u

Answer 11

-erases the whole line

Question 12

Ctrl +w

Answer 12

-erases one word in the current line

Question 13

Ctrl +d

Answer 13

-log out of current session (like “exit” command)

Question 14

Ctrl +c

Answer 14

-halts the current command

Question 15

Ctrl +l

Clear

Answer 15

-erase all

Question 16

More FILE

Answer 16

-output the contents of FILE

Question 17

!!

Answer 17

-repeats the last command

Question 18

Ssh-copy-id USER@HOST

Answer 18

-add your key to HOST for USER to enable a keyed or password-less login

Question 19

W

Answer 19

-display who is online

Question 20

Finger USER

Answer 20

-display information about USER

Question 21

Uname -a

Answer 21

-show kernel information

Question 22

Tar czf FILE.TAR.GZ FILE

Answer 22

-create a tar with Gzip compression

Question 23

Tar xzf FILE.TAR.GZ

Answer 23

-extract a tar using Gzip

Question 24

Du

Answer 24

-show directory space usage

Question 25

Du -sh

Answer 25

-shows usage for CURRENT directory

Question 26

Whereis APP

Answer 26

-shows possible location of APP

Question 27

Which APP

Answer 27

-show which app will be run by default

Question 28

Grep -r PATTERN DIR

Answer 28

-search reclusively for PATTERN in DIR

Question 29

Fg n

Answer 29

-brings jobs n to the background

Question 30

COMMAND | grep PATTERN

Answer 30

-search for PATTERN in the output of COMMAND

Question 31

Locate FILE

Answer 31

-find all instances of FILE

Question 32

Ssh -p PORT USER@HOST

Answer 32

-connect to HOST on port PORT as USER

Question 33

Ssh USER@HOST

Answer 33

-connect to HOST as USER

Question 34

Date

Answer 34

-shows current date and time

Question 35

Uptime

Answer 35

-show current uptime

Question 36

Whoami

Answer 36

-who you are logged in as

Question 37

Man COMMAND

Answer 37

-shows the manual for COMMAND

Question 38

Dig DOMAIN

Answer 38

-get DNS information for DOMAIN

Question 39

Dig -x HOST

Answer 39

-reverse lookup HOST

Question 40

Wget -c FILE

Answer 40

-continue a stopped download

Question 41

Make install ./configure Make

Answer 41

-install from source

Question 42

Dpkg -i PKG.DEB

Answer 42

-install a package (Debian)

Question 43

Cat > FILE

Answer 43

-places standard input into FILE

Question 44

Ps

Answer 44

-display your current active process

Question 45

Top

Answer 45

-display all running processes

Question 46

Whois DOMAIN

Answer 46

-gets Whois information for DOMAIN

Question 47

Killall PROC

Answer 47

-kill all processes named PROC

Question 48

Kill pid

Answer 48

-kill process id PID

Question 49

Tail -f FILE

Answer 49

-output the contents of a file as it grows, STARTING WITH LAST 10 LINES

Question 50

Head FILE

Answer 50

-output the first 10 lines of FILE

Question 51

Tail FILE

Answer 51

-output the last 10 lines of FILE