sigpending —
get pending signals
Standard C Library (libc, -lc)
#include <signal.h>
int
  
  sigpending(sigset_t
    *set);
The sigpending function returns a mask of the signals
  pending for delivery to the calling process in the location indicated by
  set. Signals may be pending because they are currently
  masked, or they are in transition before delivery (although the latter case is
  not normally detectable).
A 0 value indicates that the call succeeded. A -1 return value indicates an
  error occurred and errno is set to indicate the reason.
sigpending() will fail if:
  - [EFAULT]
- set specifies an invalid address.
Thesigpending function conforms to
  IEEE Std 1003.1-1990 (“POSIX.1”).