basic file permissions in linux

•   Permissions are a type of access control to users and groups on system resources.

• We have three methods of basic permissions such as “Read, Write and Execute.”

• These permissions can be assigned at three levels such as Owner, Group and Others.

Read: To view content of files / view list of data in directories.

Write: To write content of files / create data under directories.

Execute: To run binaries files / commands.

UMASK

UMASK stands for “User file creation mask” that controls the system file permissions.

The default file permissions are assigned by the system whenever you create any object, those default permissions values are based on UMASK value of the user.

• Default UMASK value for Super user is 022

• Default UMASK value for Normal user is 002.

DISK QUOTA

Quota is a Mechanism, which is used to restrict USERS to usage of Hard disk space, So that we can provide disk usage limitation to users & groups.

ACL

ACL - Access control list, we can provide different file permissions to individual users and groups on files.

SUDO

SUDO allows users to run another user’s programs with the security privileges. (Normally - super-user or root)

NOTE: I will explain practical in next post.