Summary of the foundation of Information security system design

Interim Summary

First, common commands

Man-k;grep;cheat;find;locate;apt-get.

Second, the regular expression

① find match, retrieve, replace

② +  indicates that the preceding character must appear at least once (1 or more times)

　　　 ? Indicates that the preceding character appears at most once (0 or 1 times)

　　　 * The asterisk indicates that the preceding character may not appear, or can occur one or more times (0, or 1, or multiple times)

Character	Describe
\	marks the next character as a special character, or a literal character. For example, "n" matches the character "n". "\ n" matches a line break. The sequence "\ \" matches "\" and "\ (" Matches "(".
^	Matches the starting position of the input string.
$	Matches the end position of the input string.
N	N is a non-negative integer. matches the determined n times . For example, "o{2}" cannot match "O" in "Bob", but can match two o in "food".
{N,}	N is a non-negative integer. match at least n times . For example, "o{2,}" cannot match "O" in "Bob", but can match all o in "Foooood". "O{1,}" is equivalent to "o+". "O{0,}" is equivalent to "o*".
{N,m}	Both M and n are non-negative integers, where n<=m. matches at least N times and matches up to M times. For example, "o{1,3}" will match the first three o in "Fooooood". "o{0,1}" is equivalent to "O?". Note that there can be no spaces between a comma and two numbers.
*	matches the preceding subexpression 0 or more times. For example, zo* can match "Z", "Zo", and "zoo". * Equivalent to {0,}.
+	matches the preceding subexpression one or more times . For example, "zo+" can Match "Zo" and "Zoo", but not "Z". + equivalent to {1,}.
?	matches the preceding subexpression 0 or one time . For example, "Do (es)?" You can match "do" in "do" or "does".?
?	When the character immediately follows any other restriction (*,+,?,{n},{n,},{n,m}), the matching pattern is non-greedy. The non-greedy pattern matches the searched string as little as possible, while the default greedy pattern matches as many of the searched strings as possible. For example, for the string "Oooo", "o+?" A single "O" will be matched, and "o+" will match all "O".
.	matches any single character except "\ n" . To match any character that includes "\ n", use a pattern like "(. |\n)".
(pattern)	matches the pattern and obtains this matching substring . This substring is used for backward referencing. To match the parentheses character, use "\ (" or "\").
X|y	match x or y. For example, "Z|food" can match "Z" or "food". "(z|f) Ood" matches "Zood" or "food".
[XYZ]	Character set (character Class). matches any one of the characters contained . For example, "[ABC]" can Match "a" in "plain". Where special characters have only backslashes \ Hold special meanings for escaping characters. Other special characters Furus, plus, all kinds of parentheses are used as ordinary characters. Caret ^ If it appears in the first place, it represents a negative character set, and if it appears in the middle of a string, it is only ordinary characters. a hyphen - appears in the middle of the string to denote a character range description, or only as a normal character if it appears in the first place.
[^XYZ]	Exclusion type (negate) character set. matches any character that is not listed. for example, "[^ABC]" can match "Plin" in "plain".
[A-z]	The character range. matches any character within the specified range. for example, "[A-z]" can match any lowercase alphabetic character in the range "a" to "Z".
[^a-z]	The character range of the exclusion type. matches any character that is not in the specified range . For example, "[^a-z]" can match any character that is not in the range "a" to "Z".

Third, tools

①vim Editor:

Normal switch to insert: i

Insert switch to normal: ESC

Normal switch to command line::

command line switch to normal: ESC

②gcc

Pretreatment: Gcc–e hello.c–o hello.i

Compilation: Gcc–s hello.i–o Hello.s

Compilation: Gcc–c hello.s–o hello.o

Link: gcc hello.o–o hello

③gdb

gdb Programm (start gdb)

B Set Breakpoints (4 breakpoints are set: Line breakpoint, function breakpoint, conditional breakpoint, temporary breakpoint)

Run starts running the program

BT Print function Call stack

P View variable values

C continue running from the current breakpoint to the next breakpoint

N Single Step operation

S Single Step operation

Quit Quit GDB

* Using disassemable mate B to set breakpoints You can view the assembly code for the program

Iv. main contents of textbooks

Chapter II Representation and processing of information

Floating-point arithmetic does not overflow, but the result of calculation is a approximate range, not very accurate, different calculation process will have different calculated values.

① binary decimals: Weight 2^ (-W) (W is the number to the right of the decimal point)

②ieee floating point representation: symbol, MANTISSA, order code

Normalized values, non-normalized values, special values

③ floating-Point arithmetic: addition: does not have the binding law, satisfies the monotonicity

Floating-point numbers for ④c languages: float, double

Chapter III Machine-level representation of the program

Assembly command:

mov--transmitting data

add--Plus

sub--minus

imul--Multiply (signed)

xor--XOR

or--or

and--and

leal--delivery address

inc--Plus One

dec--minus One

neg--fetch and fill

not--take negative

Sal (SHL)--shift left

sar--Arithmetic Right Shift

shr--Logical Right Shift

loop--Cycle

Fourth Chapter processor Architecture

the order of the Y86 is implemented: refer, decode, execute, visit, write back, update PC

Sixth Chapter Memory Structure level

①ram/rom/disk

Ram with SRAM and DRAM, features and applications
Rom has Prom,eprom,e2prom,flash
Disk structure: Platters, tracks, sectors, gaps, cylinders; disk drives
Disk capacity
Access time: Seek, rotate, transmit
Logical Disk BLOCK: Memory can be considered as a byte array, disk can be considered as a block array
Bus
Data bus, control bus, address bus
System bus, storage bus, I/O bus

Local principle of ②: temporal locality and spatial locality
Data locality of reference
Locality of taking commands

③ Storage Hierarchy: System view (1+1>2)
Central idea: Each tier of storage devices is the next level of "cache"
The table of the control p408 understand

④ cache Structure (S,E,B,M): Cache group, cache line, block
Mapping
Hit
Cache Management

* Reference: ① experiment: The basis of regular expression

② 2-7 Weeks Blog

③ "In-depth understanding of computer systems" experiment

Interim Summary Experience:

In this interim summary, corrected a lot of ordinary reading is not seriously caused by the wrong understanding. Knowledge points to be digested at ordinary times, or accumulate up there will be a great knowledge of loopholes. For example: floating-point representation and calculation method, the original paradoxical learning, feel that they understand, the results of the interim summary found that there are still a lot of things do not understand. There are quite a few examples of that.

Usually through after-school exercises to deepen understanding of the course content is also a good way, but the focus is still to read the textbook, not reading light to see the problem is easy to make a low-level error, ask some unknown so the question. Not only after-school exercises, in the future for homework I also want to pay attention to. In the front because of the time problem did not complete homework, in the future to do a little more to improve their understanding of the textbook.

Maybe there is a problem with the layout, try to use Markdown to write a blog in the future.

Summary of the foundation of Information security system design