This section lists the names for various standard kinds of signals and describes what kind of event they mean. Each signal name is a macro which stands for a positive integer---the signal number for that kind of signal. Your programs should never make assumptions about the numeric code for a particular kind of signal, but rather refer to them always by the names defined here. This is because the number for a given kind of signal can vary from system to system, but the meanings of the names are standardized and fairly uniform.
The signal names are defined in the header file `signal.h'.
NSIG is also one greater than the largest defined signal number.
| Program Error Signals | Used to report serious program errors. |
| Termination Signals | Used to interrupt and/or terminate the program. |
| Alarm Signals | Used to indicate expiration of timers. |
| Asynchronous I/O Signals | Used to indicate input is available. |
| Job Control Signals | Signals used to support job control. |
| Operation Error Signals | Used to report operational system errors. |
| Miscellaneous Signals | Miscellaneous Signals. |
| Signal Messages | Printing a message describing a signal. |