sigqueue(3)						     Library Functions Manual						       sigqueue(3)

NAME

       sigqueue -  Queues a signal and data to a running process

LIBRARY

       Realtime Library (librt.so, librt.a)

SYNOPSIS

       #include <signal.h>

       int sigqueue (
       pid_t pid,
       int signo,
       const union sigval value);

PARAMETERS

       pid     Specifies the ID of the target process.

       signo   Specifies  the  signal  to  be  queued. If the signo parameter is 0 (the null signal), error checking is performed but no signal is
	       sent. This can be used to check the validity of the pid parameter.

       value   Specifies the application-defined value to be queued to the receiving process.

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.

       The conditions required for a process to have permission to queue a signal to another process are the same as for the kill function.

       If the call is successful, the signal is queued to the specified process. If the process has the SA_SIGINFO flag  enabled  for  the  queued
       signal,	the  specified	value is delivered to its signal handler as the si_value field of the siginfo parameter. Nonprivileged callers are
       restricted  in  the  number  of	signals  they  can  have  actively  queued.  This  per-process	quota	value	can   be   returned   with
       sysconf(_SC_SIGQUEUE_MAX).

RETURN VALUES

       Upon  successful  completion,  the  sigqueue function returns a value of 0 (zero). Otherwise, a value of -1 is returned and errno is set to
       indicate the error.

ERRORS

       If sigqueue fails, no signal is sent, and errno is set to one of the following values:

       [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 signo parameter is not a valid signal number.

       [EINVAL]       The signo parameter is SIGKILL, SIGSTOP, SIGTSTP, or SIGCONT, and the pid parameter is 1 (process 1 -- init).

       [ESRCH]	      No process can be found corresponding to that specified by the pid parameter.

       [EPERM]	      The  real  or  saved user ID does not match the real or effective user ID of the receiving process, the calling process does
		      not have appropriate privilege, or the process is not sending a SIGCONT signal to one of its session's processes.

RELATED INFORMATION

       Headers: siginfo(5)

       Functions: kill(2), sigaction(2), sysconf(3)

       Guide to Realtime Programming delim off

																       sigqueue(3)