What does kill -0 PID do?

according to the man pages : 

Quote:

The signals listed below may be available for use with kill. When known constant, numbers and default behavior are shown.
NameNum ActionDescription
0 0 n/aexit code indicates if a signal may be sent

So, it does nothing, but the exit code of your "kill -0 PID" command just returns 0 if you can send a signal to PID, and returns 1 if you can't (don't have access or invalid PID)

看到这里的话大家就应该知道kill -0有啥妙用了吧

------检测一个为pid的进程是否还活着

在shell下面你可以用ps来查找，那么用c语言呢，这个不失为一个比较好的办法(kill(pid,0))