1TKILL(2)                   Linux Programmer's Manual                  TKILL(2)
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NAME

6       tkill, tgkill - send a signal to a thread
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SYNOPSIS

9       int tkill(int tid, int sig);
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11       int tgkill(int tgid, int tid, int sig);
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13       Note: There is no glibc wrapper for tkill(); see NOTES.
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DESCRIPTION

16       tgkill()  sends  the signal sig to the thread with the thread ID tid in
17       the thread group tgid.  (By contrast, kill(2) can be  used  to  send  a
18       signal  only to a process (i.e., thread group) as a whole, and the sig‐
19       nal will be delivered to an arbitrary thread within that process.)
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21       tkill() is an obsolete predecessor to tgkill().   It  allows  only  the
22       target  thread ID to be specified, which may result in the wrong thread
23       being signaled if a thread terminates and its thread  ID  is  recycled.
24       Avoid using this system call.
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26       These  are  the  raw  system call interfaces, meant for internal thread
27       library use.
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RETURN VALUE

30       On success, zero is returned.  On error, -1 is returned, and  errno  is
31       set appropriately.
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ERRORS

34       EINVAL An invalid thread ID, thread group ID, or signal was specified.
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36       EPERM  Permission denied.  For the required permissions, see kill(2).
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38       ESRCH  No  process  with  the specified thread ID (and thread group ID)
39              exists.
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41       EAGAIN The RLIMIT_SIGPENDING resource limit was reached and  sig  is  a
42              real-time signal.
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44       EAGAIN Insufficient  kernel memory was available and sig is a real-time
45              signal.
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VERSIONS

48       tkill() is supported since Linux 2.4.19 / 2.5.4.  tgkill() was added in
49       Linux 2.5.75.
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51       Library support for tgkill() was added to glibc in version 2.30.
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CONFORMING TO

54       tkill()  and tgkill() are Linux-specific and should not be used in pro‐
55       grams that are intended to be portable.
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NOTES

58       See the description of CLONE_THREAD in clone(2) for an  explanation  of
59       thread groups.
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61       Glibc does not provide a wrapper for tkill(); call it using syscall(2).
62       Before glibc 2.30, there was also no wrapper function for tgkill().
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SEE ALSO

65       clone(2), gettid(2), kill(2), rt_sigqueueinfo(2)
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COLOPHON

68       This page is part of release 5.02 of the Linux  man-pages  project.   A
69       description  of  the project, information about reporting bugs, and the
70       latest    version    of    this    page,    can     be     found     at
71       https://www.kernel.org/doc/man-pages/.
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75Linux                             2019-08-02                          TKILL(2)
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