1SIGHOLD(3P) POSIX Programmer's Manual SIGHOLD(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 sighold, sigignore, sigpause, sigrelse, sigset - signal management
13
15 #include <signal.h>
16 int sighold(int sig);
18 int sigignore(int sig);
19 int sigpause(int sig);
20 int sigrelse(int sig);
21 void (*sigset(int sig, void (*disp)(int)))(int);
22
25 Use of any of these functions is unspecified in a multi-threaded
26 process.
27 The sighold(), sigignore(), sigpause(), sigrelse(), and sigset() func‐
29 tions provide simplified signal management.
30 The sigset() function shall modify signal dispositions. The sig argu‐
32 ment specifies the signal, which may be any signal except SIGKILL and
33 SIGSTOP. The disp argument specifies the signal's disposition, which
34 may be SIG_DFL, SIG_IGN, or the address of a signal handler. If
35 sigset() is used, and disp is the address of a signal handler, the sys‐
36 tem shall add sig to the calling process' signal mask before executing
37 the signal handler; when the signal handler returns, the system shall
38 restore the calling process' signal mask to its state prior to the
39 delivery of the signal. In addition, if sigset() is used, and disp is
40 equal to SIG_HOLD, sig shall be added to the calling process' signal
41 mask and sig's disposition shall remain unchanged. If sigset() is used,
42 and disp is not equal to SIG_HOLD, sig shall be removed from the call‐
43 ing process' signal mask.
44 The sighold() function shall add sig to the calling process' signal
46 mask.
47 The sigrelse() function shall remove sig from the calling process' sig‐
49 nal mask.
50 The sigignore() function shall set the disposition of sig to SIG_IGN.
52 The sigpause() function shall remove sig from the calling process' sig‐
54 nal mask and suspend the calling process until a signal is received.
55 The sigpause() function shall restore the process' signal mask to its
56 original state before returning.
57 If the action for the SIGCHLD signal is set to SIG_IGN, child processes
59 of the calling processes shall not be transformed into zombie processes
60 when they terminate. If the calling process subsequently waits for its
61 children, and the process has no unwaited-for children that were trans‐
62 formed into zombie processes, it shall block until all of its children
63 terminate, and wait(), waitid(), and waitpid() shall fail and set errno
64 to [ECHILD].
65
67 Upon successful completion, sigset() shall return SIG_HOLD if the sig‐
68 nal had been blocked and the signal's previous disposition if it had
69 not been blocked. Otherwise, SIG_ERR shall be returned and errno set to
70 indicate the error.
71 The sigpause() function shall suspend execution of the thread until a
73 signal is received, whereupon it shall return -1 and set errno to
74 [EINTR].
75 For all other functions, upon successful completion, 0 shall be
77 returned. Otherwise, -1 shall be returned and errno set to indicate
78 the error.
79
81 These functions shall fail if:
82 EINVAL The sig argument is an illegal signal number.
84 The sigset() and sigignore() functions shall fail if:
87 EINVAL An attempt is made to catch a signal that cannot be caught, or
89 to ignore a signal that cannot be ignored.
90 The following sections are informative.
93
95 None.
96
98 The sigaction() function provides a more comprehensive and reliable
99 mechanism for controlling signals; new applications should use sigac‐
100 tion() rather than sigset().
101 The sighold() function, in conjunction with sigrelse() or sigpause(),
103 may be used to establish critical regions of code that require the
104 delivery of a signal to be temporarily deferred.
105 The sigsuspend() function should be used in preference to sigpause()
107 for broader portability.
108
110 None.
111
113 None.
114
116 Signal Concepts, exec(), pause(), sigaction(), signal(), sigsuspend(),
117 waitid(), the Base Definitions volume of IEEE Std 1003.1-2001, <sig‐
118 nal.h>
119
121 Portions of this text are reprinted and reproduced in electronic form
122 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
123 -- Portable Operating System Interface (POSIX), The Open Group Base
124 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
125 Electrical and Electronics Engineers, Inc and The Open Group. In the
126 event of any discrepancy between this version and the original IEEE and
127 The Open Group Standard, the original IEEE and The Open Group Standard
128 is the referee document. The original Standard can be obtained online
129 at http://www.opengroup.org/unix/online.html .
130IEEE/The Open Group 2003 SIGHOLD(3P)