Sometimes, your understanding of a system problem may be very general: you may know that you have a problem but cannot figure out the cause. At other times you may be able to pinpoint the part of the system causing the problem: software, hardware, a particular device such as a terminal, or a particular part of the operating system such as the file system or logical volume system. Sometimes you may know specifically what is causing a problem and want to use a particular tool to study or fix the problem.
The following sections recommend what to do when you encounter system problems or error messages.