Workbook 4

Question 1

In the output of a long listing (ls -l), which field indicates (i) the user owner and (ii) the group owner?

Answer 1

The second and third field. [4/4]

Question 2

What are the three permission types for regular files and their symbols?

Answer 2

Read (R), Write (W), Execute (X). [4/5]

Question 3

What does having the r permission for a regular file enable a user to do?

Answer 3

Read the contents of a file. [4/5]

Question 4

What does having the w permission for a regular file enable a user to do?

Answer 4

Write changes to the file. [4/5]

Question 5

What does having the x permission for a regular file enable a user to do?

Answer 5

Use the file as a command [4/5]

Question 6

What are the three access classes and their symbols?

Answer 6

User Owner (U), Group Owner (G), and Other (O). [4/5]

Question 7

If a file’s permissions are rwxr-xr-x, what are the permissions of each of the three access classes?

Answer 7

User Owner: Read, Write, and Execute.
Group Owner: Read and Execute.
Other Users: Read and Execute. [4/5]

Question 8

When you try to access a file, what questions does Linux ask and in what order?

Answer 8

1. Does the user own this file? ‘Owner’ permissions used.
2. Is the user a member of the group that owns the file? ‘Group’ permissions used.
3. ‘Other’ permissions used. [4/5]

Question 9

What are the default permissions for regular files newly created by a normal user?

Answer 9

-rw-rw-r– [4/5]

Question 10

To execute a file, what permission(s) does a user need for the file?

Answer 10

Executable permissions (X) [4/6]

Question 11

What are the permissions always for a symbolic link?

Answer 11

Full permissions. rwxrwxrwx. [4/7]

Question 12

Which user(s) can chmod a file?

Answer 12

The file owner, and root. [4/17]

Question 13

Which user(s) can chown a file?

Answer 13

Only root. [4/17]

Question 14

Which user(s) can chgrp a file?

Answer 14

The file owner, and root. [4/17]

Question 15

How is the group owner determined for a newly created file?

Answer 15

By the current primary group for the user that created the file. [4/16]

Question 16

What members comprise a user’s private group?

Answer 16

Only the user that it belongs to. [4/17]

Question 17

Can the user owner of a file change the group ownership of that file to any group?

Answer 17

They can only change the group owner to a group they are currently a member of. [4/17]

Question 18

Give the command line to change the group owner of notes.txt to group cisa

Answer 18

chgrp cisa notes.txt [4/17]

Question 19

Give the command line to change the user owner of notes.txt to user adam

Answer 19

chown adam notes.txt [4/17]

Question 20

What are the three permission types for directory files and their symbols?

Answer 20

Read (R), Write (W), Execute (X). [4/23]

Question 21

What does having the r permission for a directory allow a user to do?

Answer 21

List Directory Contents. [4/23]

Question 22

What does having the w permission for a directory allow a user to do?

Answer 22

Add or Remove files. [4/23]

Question 23

What does having the x permission for a directory allow a user to do?

Answer 23

Search for a known file in a directory. [4/23]

Question 24

Give the command line that outputs the permissions for the directory /etc

Answer 24

ls -ld /etc [4/23]

Question 25

What are the default permissions for directories newly created by a normal user?

Answer 25

Anyone and list the files, and search for them. But only the group owner and owner and add or remove files. drwxrwxr-x. [4/23]

Question 26

What are the default permissions for a user’s home directory in RHEL?

Answer 26

drwx------. Only the file owner has full permissions, group and other have none. [4/24]

Question 27

Generally, in only which two directories can a normal user create new files?

Answer 27

Their home directory (~) and tmp (/tmp). [4/24]

Question 28

When are files removed from /tmp?

Answer 28

Every 10 days. [4/24]

Question 29

In Linux, what are subdirectories named pub generally used for?

Answer 29

A folder that anybody can access. pub is short for Public.

Question 30

If you allow others access to your home directory, what should you do to protect your home directory’s subdirectories and why?

Answer 30

Remove permissions for 'others' in the folders within his home directory. [4/26]

Question 31

How are directories identified in a long listing?

Answer 31

Using the -d switch. [4/23]

Question 32

The Read (R) permission has what octal representation?

Answer 32

4. [4/32]

Question 33

The Write (W) permission has what octal representation?

Answer 33

2. [4/32]

Question 34

The Execute (X) permissions has what octal representation?

Answer 34

1. [4/32]

Question 35

The octal permissions of 755 would translate to what in symbol permissions?

Answer 35

-rwx-r-x-r-x ``` 7 = 4 + 2 + 1 = rwx for (u)ser 5 = 4 + 0 + 1 = r-x for (g)roup 5 = 4 + 0 + 1 = r-x for (o)ther [4/32] ```

Question 36

The octal permissions of 640 would translate to what in symbol permissions?

Answer 36

-rw-r----- ``` 6 = 4 + 2 + 0 = rw- for (u)ser 4 = 4 + 0 + 0 = r-- for (g)roup 0 = 0 + 0 + 0 = --- for (o)ther [4/33] ```

Question 37

The octal permissions of 701 would translate to what in symbol permissions?

Answer 37

-rwx-----x ``` 7 = 4 + 2 + 1 = rwx for (u)ser 0 = 0 + 0 + 0 = --- for (g)roup 1 = 0 + 0 + 1 = --x for (o)ther [4/33] ```

Question 38

What is the kernel’s global default for regular files?

Answer 38

666 -rw-rw-rw- [4/38]

Question 39

What is the kernel’s global default for directories?

Answer 39

777 drwxrwxrwx [4/38]

Question 40

What is the default mode of newly created (i) regular files and (ii) directories?

Answer 40

Global Default Mode [4/38]

Question 41

Give the command line to view your current umask value.

Answer 41

umask [4/39]

Question 42

Give the command line to change the umask value to 044

Answer 42

umask 044 [4/39]

Question 43

You want a different umask than the bash shell’s default. Which file do you modify to automatically change the bash shell’s umask every time you log in?

Answer 43

~/.bashrc [4/40]