The Department of Chemistry at Washington University File Protection Since UNIX is a multi-user operating system, there is a need to protect files from other users. UNIX allows fine control over file access through its protection mechanisms. Every file has one owner.
Every file has one owning group.
The group that owns the file can be verified by the ls -lg command, and can be changed by the owner of the file to another group. The user can control access to files and directories by setting the appropriate modes for the appropriate user categories. The first 10 characters of the display are the file's protection modes. In this case the type is an ordinary file. Another type of file is a directory.