C signal handling
In the C Standard Library, signal processing defines how a program handles various signals while it executes. A signal can report some exceptional behavior within the program, or a signal can report some asynchronous event outside the program.
Standard signals
The C standard defines only 6 signals. They are all defined insignal.h
header :SIGABRT
- "abort", abnormal termination.SIGFPE
- floating point exception.SIGILL
- "illegal", invalid instruction.SIGINT
- "interrupt", interactive attention request sent to the program.SIGSEGV
- "segmentation violation", invalid memory access.SIGTERM
- "terminate", termination request sent to the program.
signal.h
header by the implementation. For example, Unix and Unix-like operating systems define more than 15 additional signals; see Unix signal.Handling
A signal can be generated by callingraise
or kill
system calls. raise
sends a signal to the current process, kill
sends a signal to a specific process.A signal handler is a function which is called by the target environment when the corresponding signal occurs. The target environment suspends execution of the program until the signal handler returns or calls
longjmp
.Signal handlers can be set be with
signal
or sigaction
. The behavior of signal
has been changed multiple times across history and is now considered deprecated. It is only portable when used to set a signal's disposition to SIG_DFL or SIG_IGN. Signal handlers can be specified for all but two signals.If the signal reports an error within the program, the signal handler can terminate by calling
abort
, exit
, or longjmp
.Functions
Function | Description |
| artificially raises a signal |
| sets the action taken when the program receives a specific signal |
Example usage
- include
- include
- include
int main