2019-2020-1 20175214 "Information Security System Design Basics," the first week of learning summary

2019-2020-1 20175214 "Information Security System Design Basics," the first week of learning summary

Learning content summary

• 1, is a source of bytes, 1 byte = 8 bits;
• 2, compile the source code: the high-level language compiled into an executable object file.
  • ESC
  • ISO
  • Pretreatment: Preparation, modify the original program according to an instruction of the character c # beginning;
  • Compile: translated into assembly language;
  • Assembly: translated into machine language;
  • (?): Link function that will be called in some form incorporated into .o files, form an executable object file;
    Figure 1
• 3, linux c language compiler directive
  gcc -o hello hello.c
  • Common linux c compiler directive learning -> Links
• 4, the header file: The system reads the header file system # character stored in advance, and inserted into the program text;
  header file generally 用户构造的数据类型（如枚举类型），外部变量，外部函数、常量和内联函数等具有一定通用性或常用的量。而一般性的变量和函数定义不宜放在头文件中。(From Baidu Encyclopedia).
• 5, understand the purpose of the compilation system:
  • Optimize system performance;
  • Understand the links are errors;
  • Avoid security vulnerabilities.
• 6, ./and ../as well as /the difference between
  • ./It is the current directory
  • ../It is the parent directory
  • /It is the root directory
• 7, processes and context switching
  • Personal understanding: the need to perform the task in the process, when there are higher priority tasks to be performed, the system will be 上下文切换that the archive context of the current process of a switch execution context of the process of b, b to be completed execution process, re enter a process context;
  • Threads are generally more efficient than the process.

Textbook learning and problem-solving process

(A template: I read this passage (quoted text), there is the question (questions) I checked the information, there are these claims (quoted saying), according to my practice, I get these experiences (described his experience ). but I still do not understand, my confusion is (explain the confusion). [or] I object to the author's point of view (the author's point of view put forward their own views, as well as the grounds).)

• Question 1: class when the teacher mentioned .refers to the current directory, and ..refers to the parent directory, but I think this seems more like a path, why enter ./the system will run the file? Or ./a run command?
• Problem 1 Solution: This issue textbooks mentioned, to the effect that "If you enter a non-built-in command, shellwill assume that it is the name of an executable file, load and run." So I think the system should be in the corresponding directories to try run the program, and not that I thought of ./a run command.
• Question 2: XXXXXX
• Problem 2 Solution: XXXXXX
• ...

Code debugging and problem solving in the process

• Question 1: XXXXXX
• Problem 1 Solution: XXXXXX
• Question 2: XXXXXX
• Problem 2 Solution: XXXXXX
• ...

Code hosting

(Run results screenshot statistics.sh script)

Last week exam wrong question summary

• The wrong questions 1 and reason, to understand the situation
• Question 2 and the wrong reasons, to understand the situation
• ...

Other (perception, thinking, etc., optional)

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Learning progress bar

	The number of lines of code (add / accumulate)	Blog amount (add / accumulate)	Learning time (add / accumulate)	Important growth
aims	5000 rows	30	400 hours
the first week	200/200	2/2	20/20
the second week	300/500	2/4	18/38
The third week	500/1000	3/7	22/60
the fourth week	300/1300	2/9	30/90