tgkill(2) — Linux manual page


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

NAME         top

       tkill, tgkill - send a signal to a thread

SYNOPSIS         top

       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         top

       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
       signal 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
       library use.

RETURN VALUE         top

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

ERRORS         top

       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

       EPERM  Permission denied.  For the required permissions, see kill(2).

       ESRCH  No process with the specified thread ID (and thread group ID)

VERSIONS         top

       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         top

       tkill() and tgkill() are Linux-specific and should not be used in
       programs that are intended to be portable.

NOTES         top

       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         top

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

COLOPHON         top

       This page is part of release 5.09 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

Linux                            2019-08-02                         TKILL(2)

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