Linux – File and Folder Permission Introduction

Linux Permissions are much more simple than what is provided in Windows Active Directory. You have 3 permission types that you can apply to 3 groups. The permissions are Read, Write and Execute which can be applied to the file/folder Owner, the Group Owner and Everyone.

Permission Grouping

• Permissions are applied by Owner/ Group Owner/ Everyone
• To view permissions and owners use ls -l command in a folder.

Permissions

• Execute – Allows script execution
• Read – Allows the ability to read
• Write – Allows to modify, rename and even delete

Permission Numbers

• Execute = 1
• Write = 2
• Read = 4

Simply add numbers together to get cumulative permissions.

• 0 = – – –
• 1 = – – x
• 2 = – w –
• 3 = – w x
• 4 = r – –
• 5 = r – x
• 6 = r w –
• 7 = r w x

Examples

• 777 = Owner, Members of Group Owner, Everyone have Full Control
• 764 = Owner has Full Control, Group has Read and Write, Everyone has Read
• 740 = Owner has Full Control, Group can Read, Everyone can do nothing.