Bash Commands / Programs

Question 1

Clear

Answer 1

Clears the terminal

Question 2

Cal

Answer 2

Shows date and time

Question 3

Df

Answer 3

To see current amount of free space on our disks

Question 4

Free

Answer 4

Display the amount of free memory

Question 5

Pdw

Answer 5

Print a name of current work directory, tells you what directory you are in.

Question 6

Cd

Answer 6

Change work directory

Question 7

-a

Answer 7

–all

Question 8

-A

Answer 8

–almost-all

Question 9

-h

Answer 9

–human-readable

Question 10

-r

Answer 10

–reverse

Question 11

-rw-r–r–

Answer 11

Access rights to the file. The first character indicates the type of file. Among the different types, a leading dash means a regular file, while a d indicates a directory. The next three characters are the access rights for the file’s owner, the next three are for members of the file1’s group, and the final three are for everyone else.

Question 12

Rm

Answer 12

Remove files and directories

Question 13

Ln

Answer 13

Create hard and symbolic links

Question 14

Mkdir

Answer 14

Make directory

Question 15

Cp

Answer 15

Copy files and directories

Question 16

Mv

Answer 16

Move and rename files

Question 17

Wc

Answer 17

Word Count

Question 18

-l

Answer 18

Show lines

Question 19

Tree

Answer 19

Shows you files in a tree format

Question 20

> >

Answer 20

Add content into an existing file

Question 21

>

Answer 21

Add content into a NEW file

Question 22

Head/Tail

Answer 22

Show the x lines in that start or end of a file

Question 23

Echo

Answer 23

Echo is a shell-builtin that performs a very simple task. It prints its text arguments on standard output.

echo “this is a test”
this is a test

Question 24

~ tilde

Answer 24

When used at the beginning of a word, it expands into the name of the home directory of the named user or, if no user is named, the home directory of the current user.

Question 25

What is a Parameter?

Answer 25

It’s a feature that is more useful in shell scripts than directly on the command line. Many of its capabilities have to do with the system’s ability to store small chunks of data and to give each chunk a name.

echo $USER
Me

Question 26

What is an Escaping Character?

Answer 26

Sometimes we want to quote only a single character. To do this, we can precede a character with a backslash, which in this context is called the escape character. Often this is done inside double quotes to selectively prevent an expansion.

echo “The balance’ for user $USER is: $5.00”
The balance for user me is: $5.00

Question 27

Chmod

Answer 27

To change the mode (permissions) of a file or directory, use the chmod command. Be aware that only the file’s owner or the superuser can change the mode of a file or directory.

Question 28

Sed

Answer 28

Stream editor. Doesn’t change words, it changes regular expressions.

Question 29

Less

Answer 29

Looks at a file in a list

Question 30

Ping

Answer 30

A successful “ping” will indicate that the elements of the network (its interface cards, cabling, routing, and gateways) are in generally good working order.

Question 31

Traceroute

Answer 31

The traceroute program lists all the “hops” network traffic takes to get from the local system to a specified host. For routers that provided identifying information, we see their hostnames, IP addresses, and performance data, which includes three samples of round-trip time from the local system to the router.

Question 32

Ftp

Answer 32

Move files over network