那我就把文字打出来，也帮大家复习一下吧
(其实第一段就有Resource的定义了..)
(p88)
In general, a process will need certain resources(CPU times, memory, files,
I/O devices) to accomplish its task. When a process creates a subprocess, that
subprocess may be able to obtain its resources directly from the operating
system, or it may be constrained to a subset of the resources of the parent
process.The parent process my have to partition its resources among its
children, or it may be able to share some resouces(such as memory or files)
among several of its children. Restricting a child process to a subset of the
parent's resources prevents any process from overloading the system by
creating too many subprocesses.
(p89)
There are also two possibilities in terms of the address space of the new
process:
1. ... duplicate of the parent process...
2. ... a new program loaded into it.
(p90)
Typically, the exec() system call is used after a fork() system call by the
two processes to replace the process's memory space with a new program. ...