Linux Commands and syntax

Question 1

Command format

Answer 1

command options arguments

Question 2

/

Answer 2

absolute path

Question 3

pwd

Answer 3

print working directory

Question 4

~

Answer 4

shortcut to absolute path of home directory

Question 5

cd

Answer 5

change directory

Question 6

ls

Answer 6

list directory contents

Question 7

ls -l

Answer 7

produces a detailed long format list

Question 8

ls -lrth

Answer 8

displays files in chronological order rather than alphabetical

Question 9

t

Answer 9

time

Question 10

r

Answer 10

reverse

Question 11

h

Answer 11

human-readable

Question 12

du-h

Answer 12

disk usage reveals the size of the current directory

Question 13

mkdir

Answer 13

make directory in current directory

Question 14

!$

Answer 14

represents most recently used argument (last argument of last command)

Question 15

gedit and nano

Answer 15

text editors that can be used as commands to open or create a file in the editors

Question 16

xyz

Answer 16

file format that represents molecules: number of atoms, comment line, types of atoms and their positions in angstroms

Question 17

cp

Answer 17

copy (and rename)

Question 18

mv

Answer 18

move (and rename)

Question 19

rm

Answer 19

remove

Question 20

../

Answer 20

parent directory of current directory

Question 21

cat

Answer 21

prints the contents of the file

Question 22

less

Answer 22

allows paging through contents (of a large file) using the space bar, end with q

Question 23

head or tail -

Answer 23

retrieves the first or last (given number) of lines of a file

Question 24

tabs

Answer 24

predict and auto-type the rest of a directory or file name

Question 25

*

Answer 25

wildcard that can represent the beginning or end of any filename

Question 26

alias

Answer 26

defines a short number of characters to represent a long command

Question 27

history

Answer 27

views a history of previously typed commands

Question 28

!(number)

Answer 28

displays the numbered command in the history

Question 29

file types

Answer 29

• file
  d directory
  l link

Question 30

user types

Answer 30

u user
g group associated with the file
o other users

Question 31

permissions

Answer 31

r read
w write
x execute

Question 32

chmod

Answer 32

changes permissions e.g. chmod u+x filename

Question 33

|

Answer 33

a pipe allowing the output of the preceding command to be the input of the following command

Question 34

< and >

Answer 34

operators used to read input from or send output to files e.g. ls -R ~ > filename

Question 35

R

Answer 35

recursive

Question 36

;

Answer 36

separates commands to allow them to be run on one line

Question 37

grep

Answer 37

allows looking through the contents of a file for a given string
e.g. -i ‘look for this’ filename

Question 38

-i

Answer 38

ignore case of expression

Question 39

ssh

Answer 39

allows access to other computers
e.g. nameofcomputer

Question 40

signing in with different username

Answer 40

e.g. ssh username@host

Question 41

hamilton

Answer 41

the Durham University computational research computer, possessing over 15000 processors; full name to log in: username@hamilton.dur.ac.uk

Question 42

-Y

Answer 42

forwards graphical output to the screen when used with ssh

Question 43

PuTTY

Answer 43

provides command line execution for Windows

Question 44

:

Answer 44

separates the name of the remote computer and the path for the file to go to

Question 45

copy file from home computer to computer on mira

Answer 45

scp filename.txt username@mira.dur.ac.uk:~/

Question 46

copy file from computer on mira to home computer

Answer 46

scp username@mira.dur.ac.uk:~/filename.txt

Question 47

PATH

Answer 47

variable which tells the shell where to search for programs

Question 48

setnev

Answer 48

sets the value of environment variables

Question 49

echo

Answer 49

displays contents of a variable

Question 50

man

Answer 50

displays the manual pages for a given command, navigable by arrow kwys

Question 51

man

Answer 51

displays the manual pages for a given command, navigable by arrow keys and quitable with q

Question 52

man

Answer 52

displays the manual pages for a given command, navigable by arrow keys and quittable with q

Question 53

apropos

Answer 53

displays a list of commands for a given task

Question 54

viewer

Answer 54

selects commands that can be used for visiting files in different formats

Question 55

molden

Answer 55

used for viewing files, end by clicking a skull or typing Ctrl-c in the terminal

Question 56

babel/obabel

Answer 56

allows switching between file formats
e.g. obabel -i<input-type> input-name -o<output-type></output-type></input-type>

Question 57

jmol

Answer 57

a program that is able to view molecular structures and read xyz files