Linux Permissions and Ownership

Question 1

**

Which command we use to change permissions of a file/directory?

Answer 1

chmod <permissions> <file or
directory name>

Question 2

What are the different types of permissions in Linux?

Answer 2

read, write and execute, setuid, setgid, sticky
bit

Question 3

What are the numeric values that the system assigns for read, write, and execute?

Answer 3

read=4, write=2,
execute=1

Question 4

What are different ways to change the permissions of a file or directory?

Answer 4

permissions can be
changed symbolically using u, g, o, a, r, w, x. + to add permissions, - to take away permissions, = sets
the specified permissions.
numeric or octal and symbolic.

Question 5

What does chown -R do?

Answer 5

changes ownership recursively

Question 6

What is meant by chmod 777?

Answer 6

user, group and
other have read, write and execute permissions.

Question 7

If you want to allow different users to access a directory, how would you ensure that users would
not be able to delete each other’s files/directories?

Answer 7

set sticky bit on the directory

Question 8

How can we configure a directory called "/Project," so all the files and directories created in it by
any user have their default group to be "admins"?

Answer 8

chgrp admin /Project then chmod g+s /Project

Question 9

How can we ensure that the user owner of a directory has read, write and execute permissions,
while the group and others have only read and execute permission? Please ensure all the subdirectories/files retain the same permissions as well. (Provide exact syntax).

Answer 9

chmod -R 755
<directory name> or chmod -R u=rwx,go=rx <directory name>

Question 10

What is the purpose of umask?

Answer 10

command used to control the default permissions. user creation
mask

Question 11

What is the default umask value for the "root" user and for a regular user?

Answer 11

0022 for root
and 0002 for regular user

Question 12

If the umask value for a regular user is set to 0023, what permission will be set on a file when this user creates one?

Answer 12

644 – rw-r—r—

(0023 - mask the write permission for group, mask the write and execute permission for others)

Question 13

If the umask value for a regular user is set to 0044, what permission will be set on a directory when this user creates one?

Answer 13

733 -rwx-wx-wx

Question 14

What is Umask, and how do you set it for individual users and/or system-wide?

Answer 14

for regular
user vi .bashrc and systemwide is vi /etc/bashrc

source .bashrc will read your .bashrc file without logging you out.

Question 15

What are the 3 special permissions in Linux besides read, write, and execute?

Answer 15

set UID –
allows a file to be executed with the permissions of the file owner, set GID, Sticky bit – prevents
accidental deletion of files by other users.

Question 16

Which special permission helps prevent users from deleting each other’s files accidently in
a “collaborative” directory?

Answer 16

Sticky bit, chmod o+t or number 1

Question 17

How can you change file/directory ownership?

Answer 17

chown newowner <file or directory name>

Question 18

How to change the user owner of a file?

Answer 18

chown newowner <filename>

Question 19

How can we modify the group on the file called "/etc/test" to be "sybadm"?

Answer 19

chgrp sybadm
/etc/test

Question 20

What is the difference between chown and chmod commands?

Answer 20

chown is used to change
the user and group ownership of a file or directory

chmod is used to change the mode of
permissions for the user, group and others of a file or directory

Question 21

What is the importance of the chgrp command?

Answer 21

used to change group ownership of a file
or directory