linux programming

Question 1

list

Answer 1

ls

Question 2

what are hidden files in ls

Answer 2

beginning with dot

Question 3

list + show hidden files

Answer 3

ls -a

Question 4

show username

Answer 4

whoami

Question 5

make directory

Answer 5

mkdir directory

Question 6

change directory

Answer 6

cd

Question 7

go back (or up) one directory (switch to parent directory)

Answer 7

cd ..

Question 8

current directory

Answer 8

cd .

Question 9

get absolute pathname

Answer 9

pwd (print workind directory) - shows all parent directories

Question 10

what 3 parts is unix made up of

Answer 10

kernel, shell and programs

Question 11

what does the kernel of UNIX do?

Answer 11

The kernel of UNIX is the heart of the operating system. It
- allocates time and memory to programs and
- handles the file store and
- handles communications in response to system calls.

Question 12

Illustration of how the shell and kernel work together

Answer 12

• User types rm file
• shell searches for filestore containing program rm
• requests kernel, through system calls, to execute rm on file.
• when rm file completes, system returns $ awaiting further commands

Question 13

the shell in UNIX

Answer 13

acts as an interface between the user and kernel. The shell is a command line interpreter that allows users to type commands (or ‘talk’ to the kernel).

Question 14

create empty file

Answer 14

touch fileName.filetype

Question 15

move a file

Answer 15

mv (file to be moved) (move to this directory)

Question 16

copy a file

Answer 16

cp (originalFile.filetype) (newFile.filetype)

Question 17

remove file and directory

Answer 17

rm and rmdir but rmdir will only remove an empty directory

Question 18

display contents of a file

Answer 18

cat (concatenate)

Question 19

display first 10 lines in a file

Answer 19

head file.filetype

Question 20

display first 5 lines in a file

Answer 20

head -5 file.filetype

Question 21

write last 10 lines

Answer 21

tail file.filetype

Question 22

grab word from a file

Answer 22

grep word file.
- remember is case sensitive

Question 23

grep ignore cases

Answer 23

grep -i Science science.txt

Question 24

other grep commands

Answer 24

-v show all not containing science
-n precede each instance with the line number
-c show count of matched lines

Question 25

word count

Answer 25

wc -c , prints byte count -l, prints line count -w, prints word count

Question 26

exit entering

Answer 26

cntrl D

Question 27

redirect output to a file

Answer 27

cat > file - from here, enter input to file ie pear banana apple - this creates a file called list1 containing words pear, banana and apple

Question 28

append to a file

Answer 28

cat >> list1 - type to add to file

Question 29

concat two files together

Answer 29

cat list1 list2 > bigList

Question 30

sort file

Answer 30

sort < file

Question 31

assign sorted file to new file

Answer 31

sort < file > sortedFile

Question 32

get who is on the system with you and assign to a text file then sort them

Answer 32

who > names.txt sort < names.txt problematic as names.txt has to be deleted afterwards shorthand - who | sort

Question 33

see who is on the system with you

Answer 33

who

Question 34

shorthand for viewing and sorting names of those on system

Answer 34

who | sort

Question 35

view number of who

Answer 35

who | wc -l

Question 36

using pipes, display all lines of list1 and list2 containing the letter 'p'

Answer 36

cat list1 list2 | grep p | sort

Question 37

wildcards

Answer 37

* and ?

Question 38

when not sure of the name of the command

Answer 38

apropos eg. apropos copy will display commands with copy in their manual page header

Question 39

access rights

Answer 39

ls -l - access rights at left hand side of first line. if starts with d, directory - left group owners - middle group belongs - right group everyone else

Question 40

changing a file mode and options

Answer 40

(changing permissions) chmod u - user g - group o - others r - read w - write (and delete) x - execute (and access directory) + add permission - take away permission

Question 41

see info about processes

Answer 41

ps

Question 42

run sleep and run sleep in background

Answer 42

(sleep for 10 secs) sleep 10 (sleep for 10 secs in background) sleep 10 &

Question 43

suspend process running in foreground, then put it in backgtound

Answer 43

control z (suspends process) bg (puts in background)

Question 44

view running processes and restart a suspended process

Answer 44

jobs (view) fg jobnumber (restart job)

Question 45

kill a process in the foreground

Answer 45

cntrl c

Question 46

kill a process in the background

Answer 46

kill %jobnumber

Question 47

report space left on system

Answer 47

df