Reprinted with permission of the University of California Press and Tracy Kidder.
With permission from Random House, an imprint of Random House Publishing.
Excerpted by permission of Doubleday, a division of Random House, Inc.
(Or "file mode") The ability to access (read, write, execute, traverse, etc.) a file or directory. Depending on the operating system, each file may have different permissions for different kinds of access and different users or groups of users.
chmod ("change mode") is the UNIX command to change permissions.