Summary

One more lesson to go! You have come a long way from just logging into Unix to now setting permissions on files and directories. You should be very proud to be a Unix user with some solid skills learned entirely from scratch. In our next lesson, we will wrap up the book with a few more high-end commands that you can experiment with and incorporate into your other lessons, such as scripting, for example.

In this lesson, you learned the purpose of permissions, owners, and groups, which is very important to know if you want to do more than just list data in a directory. Now you can read that list and understand who has access to what and how to set that access if needed. You now know how to do this not only by setting permissions as we did, but also changing the group on the file or directory as well. You now understand what is necessary to enable other users to access your files and how to collaborate on projects using group permissions. You might want to take a few minutes to talk to your system administrator to find out how she has decided to manage groups. Also, you might want to request that groups be created that include other users with whom you want to share files.

Following is a look at some of the highlights from this lesson:

• Permissions File permissions control who can access a file, and what level of access they have to a file. The three levels of permissions are read, write, and execute. These permissions can be applied to the owner, group, or other.

• chmod The chmod command changes the permissions for a file or directory. There are two methods of operation: symbolic and numeric. They both accomplish the same thing, so use the one you feel comfortable with.

• chgrp You can change the group that a file belongs to with the chgrp function. You can change only the file to a group that you belong to.