December 2013
Intermediate to advanced
496 pages
8h 57m
Chinese
Content preview from LINUX系統程式設計 第二版
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第五章
行程管理
正如第 1 章所述，除了檔案，行程也是 Unix 系統中最基礎的抽象概念。因為目的碼
（object code）會進入執行（execution）—活躍（active）、活著（alive）、運行程式
（running program）—的狀態，所以行程不止是組合語言；它們組成自資料、資源、狀
態以及一個虛擬化的電腦。
本章中，我們將看到行程的基本功能，從建立到終止。自從最早期的 Unix 問世以來，它
的基本功能幾乎就未再變過。本章的主題—行程管理—便閃爍著歷史悠久的 Unix 原始設
計之前瞻性思維的光芒。Unix 行走了一條很少人走過的道路，它把新行程的建立與新二
元映像的載入分開。儘管這兩項任務多半是一前一後依序完成的，不過分開進行之後，
這兩項任務的試驗和發展將可獲得很大的自由度。這條很少人走過的道路讓 Unix 存活至
今，儘管多數作業系統均使用單一系統呼叫來啟動一個新程式，但是 Unix 卻需要用到兩
個：fork 以及 exec。在我們說明這兩個系統呼叫之前，讓我們先深入研究行程本身。
程式、行程以及執行緒
二元檔
（
binary
）是蟄伏在磁碟之類儲存媒體上經過編譯的可執行碼。一般來說，我
們也會使用
程式
（
program
）這個術語；我們會把大型和重要的二元檔稱為應用程式。
/bin/ls
及
/usr/bin/X11
皆為二元檔。
行程
（
process
）是一個正在運行的程式。一個行程不僅包含了被載入記憶體的二元映
像，還包括更多其他東西：虛擬記憶體的一個實例、核心資源（像是已開啟的檔案） ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.