《Operating System Concepts》学习第 48 天，p552-p579 总结，总计 28 页。

一、技术总结

1.file descriptor/file handle

(1)file descriptor(fd)

UNIX open-file pointer, created and returned to a process when it opens a file.

(2)file handle

Windows name for the open-file file descriptor.

2.allocation methods

(1)contiguous allocation

(2)linked allocation

(3)indexed allocation

3.Free-Space management

(1)bitmap/bit vector

Frequently, the free-space list is implemented as a bitmap or bit vector——bitmap/bit vector 是实现 free-space list 的一种方式。

1)定义：A string of n binary digits that can be used to represent the status of n items. The availability of each item is indicated by the value of a binary digit: 0 means that the resource is available, while 1 indicates that it is unavailable (or vice versa).

2)示例：001111001111110001100000011100000 ...

3)linked list

二、英语总结(生词：1)

1.sacrifice

(1)sacrifice: sacr-("sacred, holy, 神圣的") + -fice("to do, to make")

vt. sacrifice literally means "to make sacred, to make holy", over time, it evolves to mean "give up sth valuable for a higher purpose(牺牲)"。

(2)示例

For example, a temporary file system is used for fast storage and retrieval of nonpersistent files, while the default secondary storage file system (such as Linux ext4) sacrifices performance for reliability and features(《Operating System Concepts》第 563 页)。

关于英语的注解同步更新汇总到 https://github.com/codists/English-In-CS-Books 仓库。

三、其它

今天没有什么想说的。

四、参考资料

1. 编程

(1) Abraham Silberschatz，Peter Baer Galvin，Greg Gagne《Operating System Concepts》：https://book.douban.com/subject/30272539/

2. 英语

(1) Etymology Dictionary：https://www.etymonline.com

(2) Cambridge Dictionary：https://dictionary.cambridge.org

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