PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       pthread_kill — send a signal to a thread

SYNOPSIS

       #include <signal.h>

       int pthread_kill(pthread_t thread, int sig);

DESCRIPTION

       The  pthread_kill()  function  shall  request  that a signal be delivered to the specified
       thread.

       As in kill(), if sig is zero, error checking  shall  be  performed  but  no  signal  shall
       actually be sent.

RETURN VALUE

       Upon  successful  completion,  the  function shall return a value of zero.  Otherwise, the
       function shall return an error number. If the pthread_kill()  function  fails,  no  signal
       shall be sent.

ERRORS

       The pthread_kill() function shall fail if:

       EINVAL The value of the sig argument is an invalid or unsupported signal number.

       The pthread_kill() function shall not return an error code of [EINTR].

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       The  pthread_kill() function provides a mechanism for asynchronously directing a signal at
       a thread in the calling process. This could be used, for example, by one thread to  affect
       broadcast delivery of a signal to a set of threads.

       Note  that pthread_kill() only causes the signal to be handled in the context of the given
       thread; the signal action (termination or stopping) affects the process as a whole.

RATIONALE

       If an implementation detects use of a thread ID after the  end  of  its  lifetime,  it  is
       recommended that the function should fail and report an [ESRCH] error.

       Existing  implementations  vary  on  the  result  of  a  pthread_kill()  with  a thread ID
       indicating an inactive thread (a terminated thread that has not been detached or  joined).
       Some  indicate  success  on such a call, while others give an error of [ESRCH].  Since the
       definition of thread lifetime in this volume of POSIX.1‐2017 covers inactive threads,  the
       [ESRCH]  error  as described is inappropriate in this case. In particular, this means that
       an  application  cannot  have  one  thread  check  for   termination   of   another   with
       pthread_kill().

FUTURE DIRECTIONS

       A future version of this standard may require that pthread_kill() not fail with [ESRCH] in
       the case of sending signals to an inactive thread (a terminated thread not yet detached or
       joined), even though no signal will be delivered because the thread is no longer running.

SEE ALSO

       kill(), pthread_self(), raise()

       The Base Definitions volume of POSIX.1‐2017, <signal.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1-2017, Standard for Information Technology -- Portable  Operating  System  Interface
       (POSIX),  The  Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by
       the Institute of Electrical and Electronics Engineers, Inc and The  Open  Group.   In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .