tkill

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 is no glibc wrapper for tkill(); 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 li-
       brary use.

RETURN VALUE
       On success, zero is returned.  On error, -1 is returned, and  errno  is
       set appropriately.

ERRORS
       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).

       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.

       Library support for tgkill() was added to glibc in version 2.30.

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 a wrapper for tkill(); call it using syscall(2).
       Before glibc 2.30, there was also no wrapper function for tgkill().

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

COLOPHON
       This page is part of release 5.05 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                             2019-08-02                          TKILL(2)