tkill, tgkill - send a signal to a thread
Standard C library (
libc,
-lc)
#include <signal.h> /* Definition of SIG* constants */
#include <sys/syscall.h> /* Definition of SYS_* constants */
#include <unistd.h>
[[deprecated]] int syscall(SYS_tkill, pid_t tid, int sig);
#include <signal.h>
int tgkill(pid_t tgid, pid_t tid, int sig);
Note: glibc provides no wrapper for
tkill(), necessitating the use
of
syscall(2).
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.
On success, zero is returned. On error, -1 is returned, and
errno is set
to indicate the error.
- 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
specified.
- EPERM
- Permission denied. For the required permissions, see
kill(2).
- ESRCH
- No process with the specified thread ID (and thread group
ID) exists.
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 in glibc 2.30.
tkill() and
tgkill() are Linux-specific and should not be used in
programs that are intended to be portable.
See the description of
CLONE_THREAD in
clone(2) for an explanation
of thread groups.
Before glibc 2.30, there was also no wrapper function for
tgkill().
clone(2),
gettid(2),
kill(2),
rt_sigqueueinfo(2)