man3/gsignal.3

   1 .\" Copyright (C) 2002 Andries Brouwer <aeb@cwi.nl>
   2 .\"
   3 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   4 .\"
   5 .\" This replaces an earlier man page written by Walter Harms
   6 .\" <walter.harms@informatik.uni-oldenburg.de>.
   7 .TH GSIGNAL 3 2021-03-22 "Linux man-pages (unreleased)"
   8 .SH NAME
   9 gsignal, ssignal \- software signal facility
  10 .SH LIBRARY
  11 Standard C library
  12 .RI ( libc ", " \-lc )
  13 .SH SYNOPSIS
  14 .nf
  15 .B #include <signal.h>
  16 .PP
  17 .B typedef void (*sighandler_t)(int);
  18 .PP
  19 .BI "int gsignal(int " signum );
  20 .PP
  21 .BI "sighandler_t ssignal(int " signum ", sighandler_t " action );
  22 .fi
  23 .PP
  24 .RS -4
  25 Feature Test Macro Requirements for glibc (see
  26 .BR feature_test_macros (7)):
  27 .RE
  28 .PP
  29 .BR gsignal (),
  30 .BR ssignal ():
  31 .nf
  32     Since glibc 2.19:
  33         _DEFAULT_SOURCE
  34     Glibc 2.19 and earlier:
  35         _SVID_SOURCE
  36 .fi
  37 .SH DESCRIPTION
  38 Don't use these functions under Linux.
  39 Due to a historical mistake, under Linux these functions are
  40 aliases for
  41 .BR raise (3)
  42 and
  43 .BR signal (2),
  44 respectively.
  45 .PP
  46 Elsewhere, on System V-like systems, these functions implement
  47 software signaling, entirely independent of the classical
  48 .BR signal (2)
  49 and
  50 .BR kill (2)
  51 functions.
  52 The function
  53 .BR ssignal ()
  54 defines the action to take when the software signal with
  55 number
  56 .I signum
  57 is raised using the function
  58 .BR gsignal (),
  59 and returns the previous such action or
  60 .BR SIG_DFL .
  61 The function
  62 .BR gsignal ()
  63 does the following: if no action (or the action
  64 .BR SIG_DFL )
  65 was
  66 specified for
  67 .IR signum ,
  68 then it does nothing and returns 0.
  69 If the action
  70 .B SIG_IGN
  71 was specified for
  72 .IR signum ,
  73 then it does nothing and returns 1.
  74 Otherwise, it resets the action to
  75 .B SIG_DFL
  76 and calls
  77 the action function with argument
  78 .IR signum ,
  79 and returns the value returned by that function.
  80 The range of possible values
  81 .I signum
  82 varies (often 1\(en15 or 1\(en17).
  83 .SH ATTRIBUTES
  84 For an explanation of the terms used in this section, see
  85 .BR attributes (7).
  86 .ad l
  87 .nh
  88 .TS
  89 allbox;
  90 lbx lb lb
  91 l l l.
  92 Interface       Attribute       Value
  93 T{
  94 .BR gsignal ()
  95 T}      Thread safety   MT-Safe
  96 T{
  97 .BR ssignal ()
  98 T}      Thread safety   MT-Safe sigintr
  99 .TE
 100 .hy
 101 .ad
 102 .sp 1
 103 .SH STANDARDS
 104 These functions are available under AIX, DG/UX, HP-UX, SCO, Solaris, Tru64.
 105 They are called obsolete under most of these systems, and are
 106 broken under
 107 .\" Linux libc and
 108 glibc.
 109 Some systems also have
 110 .BR gsignal_r ()
 111 and
 112 .BR ssignal_r ().
 113 .SH SEE ALSO
 114 .BR kill (2),
 115 .BR signal (2),
 116 .BR raise (3)