Output Redirection, Regular Expressions

Question 1

What is the command to create a directory?

Answer 1

mkdir

Question 2

What is the command to remove an empty directory?

Answer 2

rmdir

Question 3

What is the command to remove a directory with contents

Answer 3

rm -r

Question 4

What is the command to create a parent directory and subdirectory?

Answer 4

mkdir -p

i.e mkdir -p parent/child

Question 5

What is the command to create a non existing file/ update the timestamp of an existing file/directory?

Answer 5

touch

i. e touch file
- m modify timestamp to specific date

Question 6

What is the command to rename a file/directory?

Answer 6

mv

i.e mv oldname newname

Question 7

What is the command to copy a directory and its contents?

Answer 7

cp -r

-R –recursive

Question 8

What the command to archive multiple files/directories?

Answer 8

tar -cf archivename file1 file2

• c create -f file
• f must be the last parameter

Question 9

What is the command to archive and compress multiple files/directories?

Answer 9

tar -cf

-z gzip -j bzip2

Question 10

What is the command to extract a compressed tar file?

Answer 10

tar -xf

-x extract -f file -C destination

Question 11

What is the command to list the contents of a tar file without extracting it?

Answer 11

tar -tf

Question 12

How do you zip compress a file?

Answer 12

zip zipfilename file1 file2

• r recursively on directories
• creates a new compressed file

Question 13

How do you uncompress a zip file?

Answer 13

unzip

Question 14

How do you gzip compress a file?

Answer 14

gzip

*directly compresses file in place

Question 15

How do you uncompress a gzip file?

Answer 15

gunzip

Question 16

How do you bzip2 compress a file?

Answer 16

bzip2

*directly compresses file in place

Question 17

How do you uncompress a bzip2 file?

Answer 17

bunzip2

Question 18

What is the command to view a file will scrolling ability?

Answer 18

less
more
/ - search ? - reverse search
*when command is running

Question 19

What is the command to view the top of a file?

Answer 19

head

-n number of lines

Question 20

What is the command to view the last lines of a file?

Answer 20

tail

-f realtime update -n number of lines

Question 21

Where are the logs stored for authentication attempts to the system?

Answer 21

/var/log/secure

Question 22

How do you use output redirection to append to a file?

Answer 22

> >

i.e ls&raquo_space; file

Question 23

How do you use output redirection to overwrite a file?

Answer 23

>

i.e ls > file

Question 24

How do you use output redirection to redirect only stdout?

Answer 24

1>

1»

Question 25

How do you use output redirection to redirect only stderr?

Answer 25

2>

2»

Question 26

What is the command to remove specified text from a file and print specific fields?

Answer 26

cut

• d delimiter -f field
  i. e cut file -d ‘ ‘ -f 4-
  i. e cut file -d : -f 1,5

Question 27

What is the command to arrange a file in alphabetical order?

Answer 27

sort

Question 28

How would you append a blank line to a file?

Answer 28

echo&raquo_space; file

Question 29

How do you count the number of word in a file?

Answer 29

wc

i. e cat file | wc
i. e wc file

Question 30

What is the regular expression to search the beginning of a line with matching characters?

Answer 30

i.e grep ^In file

Question 31

What is the regular expression to search the end of a line with matching characters?

Answer 31

$

i.e grep ing$ file

Question 32

What is the regular expression to search for a set of characters including an unknown character?

Answer 32

.

i. e grep .ast file
* equivalent of ? in globbing

Question 33

What is the regular expression to match zero or more preceding characters?

Answer 33

*

i. e grep www* file
* works opposite of globbing wildcard

Question 34

How do you grep with case insensitivity?

Answer 34

grep -i

Question 35

How do you input with stdin and output to stdout simultaneously?

Answer 35

tee

i. e date | tee file
- a append
* outputs piped input to a file and prints to shell