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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | STANDARDS | HISTORY | NOTES | SEE ALSO | COLOPHON |
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rt_sigqueueinfo(2) System Calls Manual rt_sigqueueinfo(2)
rt_sigqueueinfo, rt_tgsigqueueinfo - queue a signal and data
Standard C library (libc, -lc)
#include <linux/signal.h> /* Definition of SI_* constants */
#include <sys/syscall.h> /* Definition of SYS_* constants */
#include <unistd.h>
int syscall(SYS_rt_sigqueueinfo, pid_t tgid,
int sig, siginfo_t *info);
int syscall(SYS_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.
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 flag.
These system calls are not intended for direct application use;
they are provided to allow the implementation of sigqueue(3) and
pthread_sigqueue(3).
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 tgid 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 signal).
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:
si_code
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
tgkill(2).
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.
si_value
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.
On success, these system calls return 0. On error, they return -1
and errno is set to indicate the error.
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.
Linux.
rt_sigqueueinfo()
Linux 2.2.
rt_tgsigqueueinfo()
Linux 2.6.31.
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.
kill(2), pidfd_send_signal(2), sigaction(2), sigprocmask(2),
tgkill(2), pthread_sigqueue(3), sigqueue(3), signal(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
[email protected]
Linux man-pages 6.15 2025-05-17 rt_sigqueueinfo(2)
Pages that refer to this page: pidfd_send_signal(2), syscalls(2), tkill(2), pthread_sigqueue(3), sd_event_add_child(3), sigqueue(3), signal(7), system_data_types(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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