bsd/man/man2/sigprocmask.2

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  34 .\"     @(#)sigprocmask.2       8.1 (Berkeley) 6/4/93
  35 .\"
  36 .Dd June 4, 1993
  37 .Dt SIGPROCMASK 2
  38 .Os
  39 .Sh NAME
  40 .Nm sigprocmask
  41 .Nd manipulate current signal mask
  42 .Sh SYNOPSIS
  43 .Fd #include <signal.h>
  44 .Ft int
  45 .Fo sigprocmask
  46 .Fa "int how"
  47 .Fa "const sigset_t *restrict set"
  48 .Fa "sigset_t *restrict oset"
  49 .Fc
  50 .Sh DESCRIPTION
  51 The
  52 .Fn sigprocmask
  53 function examines and/or changes the current signal mask
  54 (those signals that are blocked from delivery).
  55 Signals are blocked if they are members of the current signal mask set.
  56 .Pp
  57 If
  58 .Fa set
  59 is not null, the action of
  60 .Fn sigprocmask
  61 depends on the value of the parameter
  62 .Fa how .
  63 The signal mask is changed as a function of the specified
  64 .Fa set
  65 and the current mask.
  66 The function is specified by
  67 .Fa how
  68 using one of the following values from
  69 .Aq Pa signal.h :
  70 .Bl -tag -width SIG_UNBLOCK
  71 .It Dv SIG_BLOCK
  72 The new mask is the union of the current mask and the specified
  73 .Fa set .
  74 .It Dv SIG_UNBLOCK
  75 The new mask is the intersection of the current mask
  76 and the complement of the specified
  77 .Fa set .
  78 .It Dv SIG_SETMASK
  79 The current mask is replaced by the specified
  80 .Fa set .
  81 .El
  82 .Pp
  83 If
  84 .Fa oset
  85 is not null, it is set to
  86 the previous value of the signal mask.
  87 When
  88 .Fa set
  89 is null,
  90 the value of
  91 .Ar how
  92 is insignificant and the mask remains unset
  93 providing a way to examine the signal mask without modification.
  94 .Pp
  95 The system
  96 quietly disallows
  97 .Dv SIGKILL
  98 or
  99 .Dv SIGSTOP
 100 to be blocked.
 101 .Sh RETURN VALUES
 102 A 0 value indicated that the call succeeded.  A -1 return value
 103 indicates an error occurred and
 104 .Va errno
 105 is set to indicated the reason.
 106 .Sh ERRORS
 107 The
 108 .Fn sigprocmask
 109 call will fail and the signal mask will be unchanged if one
 110 of the following occurs:
 111 .Bl -tag -width Er
 112 .\" ===========
 113 .It Bq Er EINVAL
 114 .Fa how
 115 has a value other than those listed here.
 116 .El
 117 .Sh SEE ALSO
 118 .Xr kill 2 ,
 119 .Xr sigaction 2 ,
 120 .Xr sigsuspend 2 ,
 121 .Xr sigsetops 3
 122 .Sh STANDARDS
 123 The
 124 .Fn sigprocmask
 125 function call is expected to
 126 conform to
 127 .St -p1003.1-88 .