Goals for this Hour

In this hour, you learn how to

• Understand file permissions settings

• Understand directory permissions settings

• Modify file and directory permissions with chmod

• Set new file permissions with chmod

• Establish default file and directory permissions with umask

• Identify the owner and group for any file or directory

The preceding hour contained the first tutorial dealing with the permissions of a file or directory using the -l option with ls. If you haven't read that hour recently, it would help to review the material. In this hour, you learn about another option to ls that tells UNIX to show the group and owner of files or directories. Two more commands are introduced and discussed in detail: chmod for changing the permissions of a file and umask for defining default permissions.