【读书笔记0102】Beginning linux programming-3rd

Chapter 1: getting start
任何一本书都不可能适合任何人，这本书适合没有任何linux经验的C程序员

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这章主要是介绍了unix linux gun的发展历史，
Unix is a trademark by The Open Group and source code belongs to SCO.
Unix phliosophy: The why we choose Unix.有点老掉牙的话题
这本书讲的却非常精辟：
1 what is Simplicity,
Small&simple in utilites
2 Focus,
It means,from the requirement ,we first break down the user needs.Then we try very small utilites which combined to perform. asinglepurpose so that easy to perform. and improve later for the betteralgorithmsand interface.
3 Reusable,
To realize the reusable,you should have the ability to find out the core of your applications. then make it a lib.
And you should well documented with simple butflexibleprogramming interface to helps others programmer.
4 Filters,
Filter is just transform. input and output ,to helps combining the programs.
5 Openfileformat
6 Flexibility:
is for the ingeniously users , never assume that user might want to do.
avoid arbitrary limits on field size,numbers limitation

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Remember the famous name:AT&T,Linus Torvalds,Helsinki,Richard Stallman on GNU,Dennis Ritchie,

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Programming Linux
1 Linux programs: two special typs: executables and scripts:
these two type can replace each other vice versa.

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What the tips I learn form. this charpter:
1  / forward slash ,remember the UNIX got the first, the DOS not.
2  C compiler C89
3  emacs is a important editor in linux
4  ./  what that means
5  the RoadMap actually -- where the tools and development resources arelocated.
ok,这是个入门的重点：那就是知道linux是如何组织和应用各个应用和工具的：默认路径，这个往往是初学者不知道的东西：
general applications: /usr/bin
administrator specific: /usr/local/bin  or/opt
usr/local will not remove while you reinstall the OS

You need to know the applications /include header files/ and thelibraryfiles.

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Some very useful flags for:
-I (uppercase letter for "i")  used for libs include path
-l (lowercase letter for "L")  find a lib's full path and name standard lib path. eg. -lm include a math libs in standard path
-L  add search directory , if not specify then it means just in current directory.

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how to generate a lib and use
1 use -C while we compile the program:
2 use ar to creat a archive

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then chapter said how a shared libraries are works

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Getting helps show us the basic help method：
1 man
2 info
3 help  eg: used in bash shell:
help set