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NAME

       tkill, tgkill - send a signal to a thread

SYNOPSIS

       int tkill(int tid, int sig);

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

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)

COLOPHON

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