User and Group Permissions Explained

Key Concepts

• User Permissions
• Group Permissions
• File and Directory Permissions
• Changing Permissions

User Permissions

User permissions determine what actions a specific user can perform on a file or directory. Each user has unique permissions that can be set to allow or deny read, write, and execute operations.

Imagine user permissions as a personalized key to a room. Each user has a key that allows them specific access, such as reading, writing, or executing actions within that room.

Example: To give the user "john" read and write permissions to a file named "report.txt", you would use the command chmod u+rw report.txt.

Group Permissions

Group permissions apply to all users within a specific group. These permissions allow multiple users to share common access rights to files and directories.

Think of group permissions as a shared key to a room. All members of the group have the same key, allowing them to perform actions based on the group's permissions.

Example: To give the group "developers" read and execute permissions to a directory named "projects", you would use the command chmod g+rx projects.

File and Directory Permissions

File and directory permissions are set using a combination of read (r), write (w), and execute (x) permissions. These permissions are categorized into three groups: owner, group, and others.

Consider file and directory permissions as locks on a safe. The owner has the master key, the group members have a shared key, and others have no key. The permissions determine what actions can be performed.

Example: A file with permissions -rwxr-xr-- means the owner can read, write, and execute; the group can read and execute; and others can only read.

Changing Permissions

Changing permissions is essential for managing access to files and directories. The chmod command is used to modify these permissions.

Think of changing permissions as adjusting the locks on a safe. The chmod command allows you to add or remove keys for the owner, group, and others.

Example: To give everyone (owner, group, and others) read and execute permissions to a file named "script.sh", you would use the command chmod a+rx script.sh.