kill(0, sig)
—Sends a signal to all processes in the current process
group.
kill(pid, sig)
—Sends a signal to a process.
kill(-pid, sig)
—Sends a signal to all processes in a process group.
kill(0, 0)
—Check validity of pid and permissions to send signals to the
all processes in the current process group, without actually sending any
signals.
kill(pid, 0)
—Check validity of pid and permissions to send signals to
the process, without actually sending any signals.
kill(-pid, 0)
—Check validity of pid and permissions to send signals to
all processes in the process group, without actually sending any signals.