rt_tgsigqueueinfo(2) — Linux manual page


RT_SIGQUEUEINFO(2)        Linux Programmer's Manual       RT_SIGQUEUEINFO(2)

NAME         top

       rt_sigqueueinfo, rt_tgsigqueueinfo - queue a signal and data

SYNOPSIS         top

       int rt_sigqueueinfo(pid_t tgid, int sig, siginfo_t *info);

       int rt_tgsigqueueinfo(pid_t tgid, pid_t tid, int sig,
                             siginfo_t *info);

       Note: There are no glibc wrappers for these system calls; see NOTES.

DESCRIPTION         top

       The rt_sigqueueinfo() and rt_tgsigqueueinfo() system calls are the
       low-level interfaces used to send a signal plus data to a process or
       thread.  The receiver of the signal can obtain the accompanying data
       by establishing a signal handler with the sigaction(2) SA_SIGINFO

       These system calls are not intended for direct application use; they
       are provided to allow the implementation of sigqueue(3) and

       The rt_sigqueueinfo() system call sends the signal sig to the thread
       group with the ID tgid.  (The term "thread group" is synonymous with
       "process", and tid corresponds to the traditional UNIX process ID.)
       The signal will be delivered to an arbitrary member of the thread
       group (i.e., one of the threads that is not currently blocking the

       The info argument specifies the data to accompany the signal.  This
       argument is a pointer to a structure of type siginfo_t, described in
       sigaction(2) (and defined by including <sigaction.h>).  The caller
       should set the following fields in this structure:

              This should be one of the SI_* codes in the Linux kernel
              source file include/asm-generic/siginfo.h.  If the signal is
              being sent to any process other than the caller itself, the
              following restrictions apply:

              *  The code can't be a value greater than or equal to zero.
                 In particular, it can't be SI_USER, which is used by the
                 kernel to indicate a signal sent by kill(2), and nor can it
                 be SI_KERNEL, which is used to indicate a signal generated
                 by the kernel.

              *  The code can't (since Linux 2.6.39) be SI_TKILL, which is
                 used by the kernel to indicate a signal sent using

       si_pid This should be set to a process ID, typically the process ID
              of the sender.

       si_uid This should be set to a user ID, typically the real user ID of
              the sender.

              This field contains the user data to accompany the signal.
              For more information, see the description of the last (union
              sigval) argument of sigqueue(3).

       Internally, the kernel sets the si_signo field to the value specified
       in sig, so that the receiver of the signal can also obtain the signal
       number via that field.

       The rt_tgsigqueueinfo() system call is like rt_sigqueueinfo(), but
       sends the signal and data to the single thread specified by the
       combination of tgid, a thread group ID, and tid, a thread in that
       thread group.

RETURN VALUE         top

       On success, these system calls return 0.  On error, they return -1
       and errno is set to indicate the error.

ERRORS         top

       EAGAIN The limit of signals which may be queued has been reached.
              (See signal(7) for further information.)

       EINVAL sig, tgid, or tid was invalid.

       EPERM  The caller does not have permission to send the signal to the
              target.  For the required permissions, see kill(2).

       EPERM  tgid specifies a process other than the caller and
              info->si_code is invalid.

       ESRCH  rt_sigqueueinfo(): No thread group matching tgid was found.

       rt_tgsigqueinfo(): No thread matching tgid and tid was found.

VERSIONS         top

       The rt_sigqueueinfo() system call was added to Linux in version 2.2.
       The rt_tgsigqueueinfo() system call was added to Linux in version

CONFORMING TO         top

       These system calls are Linux-specific.

NOTES         top

       Since these system calls are not intended for application use, there
       are no glibc wrapper functions; use syscall(2) in the unlikely case
       that you want to call them directly.

       As with kill(2), the null signal (0) can be used to check if the
       specified process or thread exists.

SEE ALSO         top

       kill(2), pidfd_send_signal(2), sigaction(2), sigprocmask(2),
       tgkill(2), pthread_sigqueue(3), sigqueue(3), signal(7)

COLOPHON         top

       This page is part of release 5.09 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at

Linux                            2019-10-10               RT_SIGQUEUEINFO(2)

Pages that refer to this page: syscalls(2)pthread_sigqueue(3)