tkill, tgkill - send a signal to a thread
int tkill(int tid, int sig);
int tgkill(int tgid, int tid, int sig);
Note: There is no glibc wrapper for
tkill(); see NOTES.
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
appropriately.
- 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 to glibc in version 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.
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().
clone(2),
gettid(2),
kill(2),
rt_sigqueueinfo(2)