tkill(2) - Linux manual page (original) (raw)

tkill(2) System Calls Manual tkill(2)

NAME top

   tkill, tgkill - send a signal to a thread

LIBRARY top

   Standard C library (_libc_, _-lc_)

SYNOPSIS top

   **#include <signal.h>** /* Definition of **SIG*** constants */
   **#include <sys/syscall.h>** /* Definition of **SYS_*** constants */
   **#include <unistd.h>**

   **[[deprecated]] int syscall(SYS_tkill, pid_t** _tid_**, int** _sig_**);**

   **#include <signal.h>**

   **int tgkill(pid_t** _tgid_**, pid_t** _tid_**, int** _sig_**);**

   _Note_: glibc provides no wrapper for **tkill**(), necessitating the use
   of [syscall(2)](../man2/syscall.2.html).

DESCRIPTION top

   **tgkill**() sends the signal _sig_ to the thread with the thread ID _tid_
   in the thread group _tgid_.  (By contrast, [kill(2)](../man2/kill.2.html) can be used to
   send a signal only to a process (i.e., thread group) as a whole,
   and the signal will be delivered to an arbitrary thread within
   that process.)

   **tkill**() is an obsolete predecessor to **tgkill**().  It allows only
   the target thread ID to be specified, which may result in the
   wrong thread being signaled if a thread terminates and its thread
   ID is recycled.  Avoid using this system call.

   These are the raw system call interfaces, meant for internal
   thread library use.

RETURN VALUE top

   On success, zero is returned.  On error, -1 is returned, and _[errno](../man3/errno.3.html)_
   is set to indicate the error.

ERRORS top

   **EAGAIN** The **RLIMIT_SIGPENDING** resource limit was reached and _sig_ is
          a real-time signal.

   **EAGAIN** Insufficient kernel memory was available and _sig_ is a real-
          time signal.

   **EINVAL** An invalid thread ID, thread group ID, or signal was
          specified.

   **EPERM** Permission denied.  For the required permissions, see
          [kill(2)](../man2/kill.2.html).

   **ESRCH** No process with the specified thread ID (and thread group
          ID) exists.

STANDARDS top

   Linux.

HISTORY top

   **tkill**()
          Linux 2.4.19 / 2.5.4.

   **tgkill**()
          Linux 2.5.75, glibc 2.30.

NOTES top

   See the description of **CLONE_THREAD** in [clone(2)](../man2/clone.2.html) for an explanation
   of thread groups.

SEE ALSO top

   [clone(2)](../man2/clone.2.html), [gettid(2)](../man2/gettid.2.html), [kill(2)](../man2/kill.2.html), [rt_sigqueueinfo(2)](../man2/rt%5Fsigqueueinfo.2.html)

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Linux man-pages 6.10 2024-07-23 tkill(2)

Pages that refer to this page:clone(2), gettid(2), kill(2), ptrace(2), rt_sigqueueinfo(2), sigaction(2), syscalls(2), raise(3), nptl(7), signal(7)