July 2019
Intermediate to advanced
480 pages
9h 35m
Chinese
Content preview from 持續交付｜使用Java
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| 第六章
用戶、權限與群組
Linux 作業系統（OS）可以像其他作業系統一樣執行多工，從一開始，Linux 在設計上
就是可讓多位用戶同時操作系統的。為了讓這種多用戶的設計妥善地運作，它必須設法
避免用戶互相影響。在實作 CD 時，了解這種用戶概念非常重要，因為你通常會建立讓
多位、不同的用戶運行的組建管道。開發者在任何環境中執行 Java app 時，通常都以
root 用戶（一種預設全能的用戶，可以在 Linux OS 上存取所有檔案與使用所有命令）
的身分執行 app（可能是因為他們習慣在本地這樣做）。但是當你在生產環境執行 app
時，務必使用特定的用戶，以及最低權限。
用戶與最小權限原則
在 IT 與電腦科學領域中，
最小權限原則
（
principle of least privilege
，也稱為
principle of minimal privilege
或
principle of least authority
）的意思是，在計算環
境的特定抽象層中，每一個模組（例如用戶、程序或程式，依主題而定）都只
能夠存取（使用）實現合法目的所需的資訊與資源。當你執行 Java app 時，這
個原則的意思是：只讓用戶帳戶擁有執行其預期功能所需的權限。例如，執行
典型的 Java app 的 OS 用戶可以訪問所需的部分本地檔案系統與網路，但無法
安裝新軟體。
最小權限原則的好處包括：
讓系統更穩定
當你限制程式碼可以對系統進行改變的範圍時，你就更容易測試它可能的
動作，以及與其他 app 的互動。
讓系統更安全 ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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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.