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



NAME
       tkill, tgkill - send a signal to a thread

SYNOPSIS
       int tkill(int tid, int sig);

       int tgkill(int tgid, int tid, int sig);

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

DESCRIPTION
       tgkill()	 sends	the signal sig to the thread with the thread ID tid in
       the thread group tgid.  (By contrast, kill(2) can be  used  to  send  a
       signal  only to a process (i.e., thread group) as a whole, and the sig-
       nal 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
       On success, zero is returned.  On error, -1 is returned, and  errno  is
       set appropriately.

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

       EPERM  Permission denied.  For the required permissions, see kill(2).

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

       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.

VERSIONS
       tkill() is supported since Linux 2.4.19 / 2.5.4.	 tgkill() was added in
       Linux 2.5.75.

CONFORMING TO
       tkill()	and tgkill() are Linux-specific and should not be used in pro-
       grams that are intended to be portable.

NOTES
       See the description of CLONE_THREAD in clone(2) for an  explanation  of
       thread groups.

       Glibc does not provide wrappers for these system calls; call them using
       syscall(2).

SEE ALSO
       clone(2), gettid(2), kill(2), rt_sigqueueinfo(2)

COLOPHON
       This page is part of release 4.10 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
       https://www.kernel.org/doc/man-pages/.



Linux				  2017-03-13			      TKILL(2)