1sigqueue(3C) Standard C Library Functions sigqueue(3C)
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6 sigqueue - queue a signal to a process
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9 #include <sys/types.h>
10 #include <signal.h>
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12 int sigqueue(pid_t pid, int signo, const union sigval value);
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16 The sigqueue() function causes the signal specified by signo to be sent
17 with the value specified by value to the process specified by pid. If
18 signo is 0 (the null signal), error checking is performed but no signal
19 is actually sent. The null signal can be used to check the validity of
20 pid.
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23 The conditions required for a process to have permission to queue a
24 signal to another process are the same as for the kill(2) function.
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27 The sigqueue() function returns immediately. If SA_SIGINFO is set for
28 signo and if the resources were available to queue the signal, the sig‐
29 nal is queued and sent to the receiving process. If SA_SIGINFO is not
30 set for signo, then signo is sent at least once to the receiving
31 process; it is unspecified whether value will be sent to the receiving
32 process as a result of this call.
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35 If the value of pid causes signo to be generated for the sending
36 process, and if signo is not blocked for the calling thread and if no
37 other thread has signo unblocked or is waiting in a sigwait(2) function
38 for signo, either signo or at least the pending, unblocked signal will
39 be delivered to the calling thread before the sigqueue() function
40 returns. Should any of multiple pending signals in the range SIGRTMIN
41 to SIGRTMAX be selected for delivery, it will be the lowest numbered
42 one. The selection order between realtime and non-realtime signals, or
43 between multiple pending non-realtime signals, is unspecified.
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46 Upon successful completion, the specified signal will have been queued,
47 and the sigqueue() function returns 0. Otherwise, the function returns
48 −1 and sets errno to indicate the error.
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51 The sigqueue() function will fail if:
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53 EAGAIN No resources are available to queue the signal. The process
54 has already queued SIGQUEUE_MAX signals that are still pend‐
55 ing at the receiver(s), or a system wide resource limit has
56 been exceeded.
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59 EINVAL The value of signo is an invalid or unsupported signal num‐
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63 ENOSYS The sigqueue() function is not supported by the system.
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66 EPERM The process does not have the appropriate privilege to send
67 the signal to the receiving process.
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70 ESRCH The process pid does not exist.
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74 See attributes(5) for descriptions of the following attributes:
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79 ┌─────────────────────────────┬─────────────────────────────┐
80 │ATTRIBUTE TYPE │ATTRIBUTE VALUE │
81 ├─────────────────────────────┼─────────────────────────────┤
82 │Interface Stability │Committed │
83 ├─────────────────────────────┼─────────────────────────────┤
84 │MT-Level │Async-Signal-Safe │
85 ├─────────────────────────────┼─────────────────────────────┤
86 │Standard │See standards(5). │
87 └─────────────────────────────┴─────────────────────────────┘
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90 kill(2), siginfo.h(3HEAD), signal.h(3HEAD), sigwaitinfo(3C),
91 attributes(5), standards(5)
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95SunOS 5.11 5 Feb 2008 sigqueue(3C)