1.4.46 signal: Change the Action for a Signal
The function is called by:
|
INTEGER*4 signal or INTEGER*8 signal n = signal( signum, proc, flag ) |
||||
|
signum |
INTEGER*4 |
Input |
Signal number; see signal(3) |
|
|
proc |
Routine name |
Input |
Name of user signal handling routine; must be in an external statement |
|
|
flag |
INTEGER*4 |
Input |
flag < 0: Use proc as the signal handler flag ≥ 0: Ignore proc; pass flag as the action: flag = 0: Use the default action flag = 1: Ignore this signal |
|
|
Return value |
INTEGER*4 |
Output |
n=-1: System error n>0: Definition of previous action n>1: n=Address of routine that would have been called n<-1: If signum is a valid signal number, then: n=address of routine that would have been called. If signum is a not a valid signal number, then: n is an error number. |
|
|
INTEGER*8 |
On 64-bit environments, signal and the variables receiving its output must be declared INTEGER*8 |
|||
If proc is called, it is passed the signal number as an integer argument.
If a process incurs a signal, the default action is usually to clean up and abort. A signal handling routine provides the capability of catching specific exceptions or interrupts for special processing.
The returned value can be used in subsequent calls to signal to restore a previous action definition.
You can get a negative return value even though there is no error. In fact, if you pass a valid signal number to signal(), and you get a return value less than -1, then it is OK.
floatingpoint.h defines proc values SIGFPE_DEFAULT, SIGFPE_IGNORE, and SIGFPE_ABORT. See 1.4.26.1 floatingpoint.h: Fortran IEEE Definitions.
In 64-bit environments, signal must be declared INTEGER*8, along with the variables receiving its output, to avoid truncation of the address that may be returned.
See also kill(1), signal(3), and kill(3F), and Numerical Computation Guide.
- © 2010, Oracle Corporation and/or its affiliates