TKILL(2) Linux Programmer's Manual TKILL(2)
NAME
tkill - send a signal to a single process
SYNOPSIS
#include<sys/types.h>
#include<linux/unistd.h>
_syscall2(int,tkill,pid_t,tid,int,sig)
inttkill(pid_ttid,intsig);
DESCRIPTION
The tkill system call is analogous to kill(2), except when the speci-
fied process is part of a thread group (created by specifying the
CLONE_THREAD flag in the call to clone). Since all the processes in a
thread group have the same PID, they cannot be individually signalled
with kill. With tkill, however, one can address each process by its
unique TID.
RETURNVALUE
On success, zero is returned. On error, -1 is returned, and errno is
set appropriately.
ERRORS
EINVAL An invalid TID or signal was specified.
ESRCH No process with the specified TID exists.
EPERM The caller did not have permission to send the signal to the
specified process. For a process to be allowed to send a signal,
it must either have root privileges, or its real or effective
user ID must be equal to the real or saved set-user-ID of the
receiving process.
CONFORMINGTO
tkill is Linux specific and should not be used in programs that are
intended to be portable.
SEEALSO
gettid(2), kill(2)
Linux 2.4.20 2003-02-01 TKILL(2)
Take our 
