stap中的entry函数

只有在ret probe函数中，在这个函数中才会使用＠entry函数去提取变量

是因为ret probe 有什么特殊的吗？在中间这个变量会变化吗？

A new operator, @entry, is available for automatically saving an expression at entry time for use in a .return probe.

但是

A SystemTap script can also accept simple command-line arguments using a

$

or

@

immediately followed

by the number of the argument on the command line. Use

$

if you are expecting the user to enter an

integer as a command-line argument, and

@

if you are expecting a string.