功能：
kill命令发送信号给进程。
格式：
kill [-s signal|-p] [-q sigval] [-a] [--] pid...
kill -l [signal]
kill [-s <信息名称或编号>][程序] 或 kill [-l <信息编号>]
参数：
OPTIONS
pid... Specify the list of processes that kill should signal. Each pid can be
one of five things:
n where n is larger than 0. The process with pid n will be sig‐
naled.
0 All processes in the current process group are signaled.
-1 All processes with pid larger than 1 will be signaled.
-n where n is larger than 1. All processes in process group n are //信息编号
signaled. When an argument of the form '-n' is given, and it is
meant to denote a process group, either the signal must be speci‐
fied first, or the argument must be preceded by a '--' option,
otherwise it will be taken as the signal to send.
commandname
All processes invoked using that name will be signaled.
-s, --signal signal //信息名称
Specify the signal to send. The signal may be given as a signal name or
number.
-l, --list [signal] //打印编号
Print a list of signal names, or convert signal given as argument to a
name. The signals are found in /usr/include/linux/signal.h
-L, --table
Similar to -l, but will print signal names and their corresponding num‐
bers.
-a, --all
Do not restrict the commandname-to-pid conversion to processes with the
same uid as the present process.
-p, --pid
Specify that kill should only print the process id (pid) of the named
processes, and not send any signals.
-q, --queue sigval
Use sigqueue(2) rather than kill(2) and the sigval argument is used to
specify an integer to be sent with the signal. If the receiving process
has installed a handler for this signal using the SA_SIGINFO flag to
sigaction(2), then it can obtain this data via the si_value field of the
siginfo_t structure.
实例：
-l 编号
1.2 发送SIGHUP信号，可以使用一下信号
1.3 彻底杀死进程
