Linux File Permissions and Commands

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Questions and Answers

What does a umask value of 002 mean for new files created in the system?

Files will have read and write permissions for all users.

Files will have read, write, and execute permissions for all users.

Files will have no write permissions for the group and others. (correct)

Files will only be executable by the owner.

Which chmod command would you use to grant read, write, and execute permissions to the owner, and only read permissions to the group and others?

chmod 700 filename

chmod 644 filename

chmod 777 filename

chmod 755 filename (correct)

What octal value represents having no permissions at all?

0 (correct)

When the default umask is set to 000, what will be the default permissions for a newly created directory?

777 Signup and view all the answers

What is the effect of the command 'chmod 644 practice' on the permissions of the file named 'practice'?

It grants read and write permissions to the owner, and read-only for group and others. Signup and view all the answers

What does the 'd' at the beginning of the mode field indicate?

It is a directory. Signup and view all the answers

What characters in the mode field represent the permissions for the user (owner) of the file?

Characters 2 through 4 Signup and view all the answers

How would you add read permission for the user (owner) of a file named 'list1' using chmod?

chmod u+r list1 Signup and view all the answers

In the command 'chmod g-w list1', what is the effect of this command?

It removes write permission from the group. Signup and view all the answers

Which of the following best describes what the 'chmod' command does?

It changes the access permissions for files or directories. Signup and view all the answers

What does the last three characters in the mode field represent?

The permissions for others. Signup and view all the answers

If a file's permission string is 'rw-r--r--', which of the following groups has write permission?

The user (owner). Signup and view all the answers

When using symbolic values with chmod, what does the '+' symbol signify?

Granting a permission. Signup and view all the answers

What is the effect of using the command 'chmod a-rwx practice'?

All permissions are removed for all users from the 'practice' directory. Signup and view all the answers

Which command would you use to allow write permission for the group and others in a directory named 'docs'?

chmod go+w docs Signup and view all the answers

What happens when the command 'chmod u-x sport' is executed and the user tries to enter the 'sport' directory?

The access to the 'sport' directory is denied. Signup and view all the answers

If 'r', 'w', and 'x' respectively represent read, write, and execute permissions, what does the octal representation of 'rwx' equal?

7 Signup and view all the answers

What command correctly sets the permissions of a file to allow read and write access for all users while removing execute permission?

chmod ugo=rw file.txt Signup and view all the answers

When using octal values with the chmod command, which represents no permissions?

0 Signup and view all the answers

What is the outcome of executing 'chmod go-w practice' on the directory?

It removes write permission from group and others. Signup and view all the answers

To set only read permission for the group on a file named 'file.txt', which command should you use?

chmod g=r file.txt Signup and view all the answers

Study Notes

File and Directory Permissions

The mode field in the ls -l command output shows file permissions.
A "d" at the start of the mode field indicates a directory, a "-" shows a file, and an "l" signifies a link to another file.
The mode field has three sections: user, group, and others, each with read, write, and execute permissions represented by "r", "w", and "x".
Hyphens within the mode field indicate that a permission is not granted.

The chmod Command

The chmod command changes file or directory permissions.
It can be used with symbolic or octal values.
Symbolic specifications include class of user (u, g, o, a), how permissions are changed (+, -, =), and permissions (r, w, x).
Octal specifications use a 3-digit number representing the combined permissions (read = 4, write = 2, execute = 1).

The umask Command

The umask command controls the default permissions given to newly created files and directories.
The system administrator usually sets the initial umask value.
The initial umask is typically 000, resulting in default directory permissions of 777 (rwxrwxrwx).

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Description

This quiz covers essential aspects of file and directory permissions in Linux, including the interpretation of the 'ls -l' command and the application of 'chmod' and 'umask' commands. Test your understanding of how to manage user, group, and others' permissions effectively within a Linux environment.