Send the signal sig to the process with
the process identifier pid.
参数
pid
The process identifier.
sig
One of the PCNTL signals constants.
返回值
成功时返回 TRUE, 或者在失败时返回 FALSE.
参见
The kill(2) manual page of the POSIX system, which contains additional
information about negative process identifiers, the special pid 0, the
special pid -1, and the signal number 0.