sigqueue(2) [debian man page]
SIGQUEUE(2) BSD System Calls Manual SIGQUEUE(2) NAME
sigqueue -- queue a signal to a process (REALTIME) LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <signal.h> int sigqueue(pid_t pid, int signo, const union sigval value); DESCRIPTION
The sigqueue() system call causes the signal specified by signo to be sent with the value specified by value to the process specified by pid. If signo is zero (the null signal), error checking is performed but no signal is actually sent. The null signal can be used to check the validity of PID. The conditions required for a process to have permission to queue a signal to another process are the same as for the kill(2) system call. The sigqueue() system call queues a signal to a single process specified by the pid argument. The sigqueue() system call returns immediately. If the resources were available to queue the signal, the signal will be queued and sent to the receiving process. If the value of pid causes signo to be generated for the sending process, and if signo is not blocked for the calling thread and if no other thread has signo unblocked or is waiting in a sigwait() system call for signo, either signo or at least the pending, unblocked signal will be delivered to the calling thread before sigqueue() returns. Should any multiple pending signals in the range SIGRTMIN to SIGRTMAX be selected for delivery, it is the lowest numbered one. The selection order between realtime and non-realtime signals, or between multiple pending non- realtime signals, is unspecified. RETURN VALUES
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error. ERRORS
The sigqueue() system call will fail if: [EAGAIN] No resources are available to queue the signal. The process has already queued {SIGQUEUE_MAX} signals that are still pending at the receiver(s), or a system-wide resource limit has been exceeded. [EINVAL] The value of the signo argument is an invalid or unsupported signal number. [EEPERM] The process does not have the appropriate privilege to send the signal to the receiving process. [ESRCH] The process pid does not exist. SEE ALSO
sigaction(2), sigpending(2), sigqueue(2), sigsuspend(2), sigtimedwait(2), sigwait(2), sigwaitinfo(2), pause(3), pthread_sigmask(3), siginfo(3) STANDARDS
The sigqueue() system call conforms to IEEE Std 1003.1-2004 (``POSIX.1'') HISTORY
Support for POSIX realtime signal queue first appeared in FreeBSD 7.0. BSD
November 11, 2005 BSD
Check Out this Related Man Page
sigqueue(3RT) Realtime Library Functions sigqueue(3RT) NAME
sigqueue - queue a signal to a process SYNOPSIS
cc [ flag... ] file... -lrt [ library... ] #include <sys/types.h> #include <signal.h> int sigqueue(pid_t pid, int signo, const union sigval value); DESCRIPTION
The sigqueue() function causes the signal specified by signo to be sent with the value specified by value to the process specified by pid. If signo is 0 (the null signal), error checking is performed but no signal is actually sent. The null signal can be used to check the validity of pid. The conditions required for a process to have permission to queue a signal to another process are the same as for the kill(2) function. The sigqueue() function returns immediately. If SA_SIGINFO is set for signo and if the resources were available to queue the signal, the signal is queued and sent to the receiving process. If SA_SIGINFO is not set for signo, then signo is sent at least once to the receiving process; it is unspecified whether value will be sent to the receiving process as a result of this call. If the value of pid causes signo to be generated for the sending process, and if signo is not blocked for the calling thread and if no other thread has signo unblocked or is waiting in a sigwait(2) function for signo, either signo or at least the pending, unblocked signal will be delivered to the calling thread before the sigqueue() function returns. Should any of multiple pending signals in the range SIGRT- MIN to SIGRTMAX be selected for delivery, it will be the lowest numbered one. The selection order between realtime and non-realtime sig- nals, or between multiple pending non-realtime signals, is unspecified. RETURN VALUES
Upon successful completion, the specified signal will have been queued, and the sigqueue() function returns 0. Otherwise, the function returns -1 and sets errno to indicate the error. ERRORS
The sigqueue() function will fail if: EAGAIN No resources are available to queue the signal. The process has already queued SIGQUEUE_MAX signals that are still pending at the receiver(s), or a system wide resource limit has been exceeded. EINVAL The value of signo is an invalid or unsupported signal number. ENOSYS The sigqueue() function is not supported by the system. EPERM The process does not have the appropriate privilege to send the signal to the receiving process. ESRCH The process pid does not exist. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |Async-Signal-Safe | +-----------------------------+-----------------------------+ SEE ALSO
kill(2), siginfo.h(3HEAD), signal.h(3HEAD), sigwaitinfo(3RT), attributes(5), standards(5) SunOS 5.10 28 Jun 2002 sigqueue(3RT)