#include <signal.h> int
Fo sigprocmask
Fa int how
Fa const sigset_t * restrict set
Fa sigset_t * restrict oset
Fc
DESCRIPTION
The
sigprocmask ();
system call examines and/or changes the current signal mask (those signals
that are blocked from delivery).
Signals are blocked if they are members of the current signal mask set.
If
Fa set
is not null, the action of
sigprocmask ();
depends on the value of the
Fa how
argument.
The signal mask is changed as a function of the specified
Fa set
and the current mask.
The function is specified by
Fa how
using one of the following values from
In signal.h :
SIG_BLOCK
The new mask is the union of the current mask and the specified
Fa set .
SIG_UNBLOCK
The new mask is the intersection of the current mask
and the complement of the specified
Fa set .
SIG_SETMASK
The current mask is replaced by the specified
Fa set .
If
Fa oset
is not null, it is set to
the previous value of the signal mask.
When
Fa set
is null,
the value of
Fa how
is insignificant and the mask remains unset
providing a way to examine the signal mask without modification.
The system
quietly disallows
SIGKILL
or
SIGSTOP
to be blocked.
RETURN VALUES
Rv -std sigprocmask
ERRORS
The
sigprocmask ();
system call will fail and the signal mask will be unchanged if one
of the following occurs:
Bq Er EINVAL
The
Fa how
argument
has a value other than those listed here.
