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 only be used to
       send a signal 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 only allows 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.

       If tgid is specified as -1, tgkill() is equivalent to tkill().

       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.

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 programs 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 3.44 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2012-07-13								  TKILL(2)