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);

DESCRIPTION
       tgkill()  sends  the signal sig to the thread with the thread ID tid in the thread group tgid.  (By contrast, kill(2) can
       only be used to send a signal to a process (i.e., thread group) as a whole, and the signal will be delivered to an  arbi-
       trary thread within that process.)

       tkill() is an obsolete predecessor to tgkill().  It only allows 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.

       If tgid is specified as -1, tgkill() is equivalent to tkill().

       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.

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)

COLOPHON
       This page is part of release 3.25 of the Linux man-pages project.  A description of the project,  and  information  about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



Linux                                                      2008-10-01                                                   TKILL(2)