shell basics

Question 1

ls

Answer 1

lists directory contents

Question 2

ls -l

Answer 2

uses long listing format

Question 3

ls -v

Answer 3

explains what is being done

Question 4

mkdir -p

Answer 4

makes parents

Question 5

rmdir -p

Answer 5

removes dir and its ancestors

Question 6

mkdir

Answer 6

makes dir

Question 7

rmdir

Answer 7

removes empty dir

Question 8

rm

Answer 8

removes files and dir

Question 9

rm -r

Answer 9

removes dir and their contents recursively

Question 10

rm -i

Answer 10

checks before every removal

Question 11

cp

Answer 11

copies files and dir

Question 12

cp -r

Answer 12

copies recursively

Question 13

cp -v

Answer 13

explains what is being done

Question 14

mv

Answer 14

moves(renames) files

Question 15

mv -v

Answer 15

explains what is being done

Question 16

touch

Answer 16

changes file timestamps; creates new file if it doesn’t exist

Question 17

touch -c

Answer 17

doesn’t create new files

Question 18

touch -a

Answer 18

only changes access time

Question 19

touch -m

Answer 19

only changes modificiation time

Question 20

touch -t

Answer 20

changes time to [[CC]MMDDhhmm[.ss] instead of current time

Question 21

cat

Answer 21

concatenates files and prints on the standard output

Question 22

cat

Answer 22

prints on the standard output

Question 23

cat -n

Answer 23

numbers all output lines

Question 24

cat -s

Answer 24

suppresses repeated empty output lines

Question 25

cat -T

Answer 25

displays TAB char as ^I

Question 26

wc

Answer 26

prints newline, word and byte count

Question 27

wc -c

Answer 27

bytes

Question 28

wc -l

Answer 28

lines

Question 29

wc -w

Answer 29

words

Question 30

grep

Answer 30

matches patterns

Question 31

cut

Answer 31

removes sections from each line of files

Question 32

sort

Answer 32

sorts lines

Question 33

sort -v

Answer 33

explains what is being done

Question 34

sort -u

Answer 34

uniq

Question 35

sort -r

Answer 35

reverse

Question 36

sort -n

Answer 36

numeric sort

Question 37

cut -d

Answer 37

delimiter

Question 38

cut -f

Answer 38

field

Question 39

cut -c

Answer 39

only these chaarcters

Question 40

tr

Answer 40

translate or delete char

Question 41

tr -d

Answer 41

delete char in SET1

Question 42

tr -c

Answer 42

use the complement of SET1

Question 43

tr -t

Answer 43

first truncate SET1 to length of SET2

Question 44

echo

Answer 44

displays a line of text

Question 45

echo -n

Answer 45

suppresses trailing newline

Question 46

echo -e

Answer 46

enable interpretation of backslash escapes

Question 47

echo -E

Answer 47

disable interpretation of backslash escapes (default)

Question 48

>-

Answer 48

save

Question 49

<-

Answer 49

read

Question 50

>>

Answer 50

append

Question 51

<<

Answer 51

here-doc

Question 52

<<<

Answer 52

here-string

Question 53

sort -t ""

Answer 53

field separator

Question 54

uniq -d

Answer 54

display only the duplicate lines

Question 55

uniq -c