Command Line

Question 1

Prompt

Answer 1

$

For Amazon Linux

Question 2

Cursor

Answer 2

Where anything typed will show up

Question 3

echo

Answer 3

display text in output

Question 4

pwd

Answer 4

present working directory

Question 5

command format

Answer 5

[command] [arguments…]

Question 6

man [command]

Answer 6

Displays manual for [command]

Type “q” to exit manual.

Question 7

Command Line Uses

Answer 7

Restart servers
Rename hundreds or thousands of files according to a prescribed pattern
Manage system logs
Set up scheduled tasks (cron jobs)
Debug server issues
Monkey patch code on a server
Query data
Set up databases and servers
--- and many more

Question 8

cd [directory]

Answer 8

change directory

by itself, changes to the home directory, and with argument goes to the indicated directory

Question 9

ls

Answer 9

list files and directories in current directory

Question 10

pwd

Answer 10

display the path of the current directory

Question 11

touch

Answer 11

create a file

Question 12

mkdir

Answer 12

make directory

Question 13

rm

Answer 13

remove a file or directory

Is permanent!

Question 14

cp

Answer 14

copy a file or directory

Question 15

mv [source] [destination]

Answer 15

move or rename a file or directory
movement is relative to current directory
.. = parent directory
. = current directory
/[directory name] = child directory

Question 16

cat

Answer 16

display contents of a file

Question 17

more

Answer 17

displays contents of a file, starting at the top and letting the user scroll down

Question 18

less

Answer 18

display contents of a file in an even ore interactive way

Question 19

head

Answer 19

displays first part of a file

Question 20

tail

Answer 20

displays last part of a file

Question 21

cd /

Answer 21

change to parent directory

Question 22

ls -1

Answer 22

lists files and directories in the current directory, each on a new row of output

Question 23

cd ~

Answer 23

change to home directory

cd $HOME also works

Question 24

q

Answer 24

exit current screen, eg “man”, “more”, etc.

Question 25

clear

Answer 25

clears current output screen

Question 26

/

Answer 26

root directory, or separator for listing directories

Question 27

, or ./

Answer 27

current directory

Question 28

.. or ../

Answer 28

parent directory

Question 29

../..

Answer 29

grand parent directory

Question 30

*

Answer 30

wildcard

Question 31

ls -a

Answer 31

includes hidden files in list | " ls -d .* " lists only the hidden files

Question 32

ls -lah

Answer 32

Get detailed information about the files and directories listed

Question 33

which [command]

Answer 33

shows the directory where the executable exists for the [command]

Question 34

env

Answer 34

display environment variables and values

Question 35

variable="value"

Answer 35

how to set an environment variable value | note that there are no spaces

Question 36

ps1

Answer 36

environment variable for the prompt

Question 37

.bashrc, .bash_profile

Answer 37

``` environment files (for bash, not Zsh) nano ~/.bashrc to edit ```

Question 38

bin

Answer 38

binary: executable file

Question 39

PATH

Answer 39

environment variable. determines which directories are searched when a command is entered an ordered, colon-delimited list of directories that contain executables PATH can be amended to add directories for executables to permanently change PATH: .bashrc

Question 40

rwx

Answer 40

read, write, exectute

Question 41

drwxrwxr-x 3 ec2-user ec2-user practice

Answer 41

rwx = read, write, execute d | rwx | rwx | r-x | 3 |ec2-user | ec2-user | practice directory | User wx | Group rwx | Other rwx | # files | user name | group name | file / directory name

Question 42

chmod u-w test.txt

Answer 42

add write permissions for user to file test.txt

Question 43

chmod 777 text.sh

Answer 43

``` set permissions on text.sh to read, write, and execute for all users, groups, others. Number Permission 0 No permission granted. 1 Can execute. 2 Can write. 3 Can write and execute (2 + 1 = 3). 4 Can read. 5 Can read and execute (4 +1 = 5). 6 Can read and write (4 + 2 = 6). 7 Can read and write and execute (4 + 2 + 1 = 7). ```

Question 43

chmod 777 text.sh

Answer 43

set permissions on text.sh to read, write, and execute for all users, groups, others. Number Permission 0 No permission granted. 1 Can execute. 2 Can write. 3 Can write and execute (2 + 1 = 3). 4 Can read. 5 Can read and execute (4 +1 = 5). 6 Can read and write (4 + 2 = 6). 7 Can read and write and execute (4 + 2 + 1 = 7).

Question 44

groups

Answer 44

display the groups for current user

Question 45

su

Answer 45

switch user | su - = switch to root user, password entry may be required

Question 46

REPL

Answer 46

Read-Eval-Print-Loop