Users & Groups

Permissions & Ownership

How file permissions, users, and ownership models compare.

The Core Philosophy

Both systems control who can do what with files, but their underlying architectures are very different.

Windows (ACLs)

Windows uses Access Control Lists (ACLs). A file or folder can have a highly granular list of rules defining exactly what specific users or groups can or cannot do.

Permissions are inherited from parent folders by default.
”Deny” rules always override “Allow” rules.
Permissions include Full Control, Modify, Read & Execute, Read, and Write.

Linux (UGO / POSIX)

Linux traditionally uses the UGO (User, Group, Others) model. Every file has exactly one owning user and one owning group.

Permissions are Read (r), Write (w), and Execute (x).
These three permissions are set separately for the Owner, the Group, and Everyone Else.
While Linux supports ACLs for more complex setups, the simple UGO model is the default and most common.

Viewing Permissions

Get-Acl .\myfile.txt

ls -l myfile.txt

Output looks like: -rw-r—r—

Modifying Permissions

Modifying ACLs via command line is complex (icacls).

Often better handled via GUI or specialized modules.

icacls .\myfile.txt /grant “Users:(R,W)“

chmod (change mode)

Add write permission for the owning group

chmod g+w myfile.txt

Or using octal (755 = rwxr-xr-x)

chmod 755 myfile.sh