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 are no glibc wrappers for these system calls; 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 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

       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.

       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.

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), rt_sigqueueinfo(2)

COLOPHON

       This  page  is  part of release 4.15 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/.