Users who cannot access a program, a file, or a directory that they previously could, often call a system administrator for help:
When you encounter such a problem, investigate one of the following possibilities:
Whether the user's search has been changed or the directories in the search path are not in the proper order.
Whether the file or directory has the proper permissions or ownership.
Whether the configuration of a system accessed over the network has changed.
This chapter briefly describes how to recognize problems in each of these three areas and suggests possible solutions.