### Default Signal Handlers

The run-time environment performs default signal handling, unless you do one of the following for specific signals:

- Register another signal handler
- Disable the signal by setting the handler to SIG_IGN

The default handling depends upon the signal that is being handled. For most signals, the default is to pass the signal to the next exception handler in the chain. Unless you have set up your own exception handler, the default exception handler receives the signal and performs the default action, which is to terminate the program and return an exit code. The exit code indicates:

1. The reason for the program termination.
   On OS/2, the codes are the same as the return codes of the OS/2 API DosExecProgram.
   On Windows, the termination codes are the same as for the Windows API CreateProcess.
2. The return code of the OS/2 API DosExit.
   The return code of the Windows API ExitThread.

The C signals supported by the IBM C and C++ Compilers run-time library, the source of the signals, and the default handling are documented along with the signal function, in the C Library Reference.

The signal constants are defined in the <signal.h> header file.

Signals and Exceptions
Signal and Exception Handling

Program Signal Handling

OS/2 Default Exception Handling
Windows Default Exception Handling