AppleLin的博客

ida demo

Thu, 11 Feb 2021 17:27:45 +0800

文章出自个人博客，转载请申明

问题

用 ida 修改 demo.exe, 改变 demo.exe的运行。

//demo.exe
//#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>


int main()
{
	int n;
	scanf("%d", &n);
	if (n > 0)
		printf("a > 0");  //IDA把'a'改成'n'
	else
		printf("n < 0");
}

反汇编修改a > 0为n>0

用ida打开demo.exe.

Graph view

IDA View-A

看到 aA0是 “a > 0”

Hex view

查看哪里调用了”a > 0”

string view

ctrl + f , find a > 0

g + 00403003

ctrl+x

view -> Open subviews -> Hex dump

新年快乐

shuffle string

Tue, 26 Jan 2021 12:30:08 +0800

文章出自个人博客，转载请申明

问题

shuffle-string 给你一个字符串 s 和一个长度相同的整数数组 indices 。请你重新排列字符串 s ，其中第 i 个字符需要移动到 indices[i] 指示的位置。返回重新排列后的字符串。

示例 1：

输入：s = "codeleet", indices = {4,5,6,7,0,2,1,3}
输出："leetcode"
解释：如图所示，"codeleet" 重新排列后变为 "leetcode" 。

示例 2：

输入：s = "abc", indices = {0,1,2}
输出："abc"
解释：重新排列后，每个字符都还留在原来的位置上。

示例 3：

输入：s = "aiohn", indices = {4,1,3,0,2}
输出："nihao"

示例 4：

输入：s = "aaiougrt", indices = {4,0,2,6,7,3,1,5}
输出："uairtoag"

示例 5：

输入：s = "art", indices = {1,0,2}
输出："rat"

分析

You can create an auxiliary string t of length n.

Assign t[i] to s[indexes[i]] for each i from 0 to n-1.

解决方案

方法一

class Solution
{
private:
    /* data */
public:
    Solution(/* args */);
    ~Solution();
    static void restoreString(string& s, vector<int>& indices);
    static void test()
    {
        test0();
        test1();
        test2();
        test3();
        test4();
    }

    static void test0()
    {
        string s1 = "codeleet";
        int arr1[] = {4,5,6,7,0,2,1,3};
        vector<int> iv1(begin(arr1), end(arr1));
        restoreString(s1, iv1);
    }

    static void test1()
    {
        string s = "aiohn";
        int arr[] = { 4,1,3,0,2};
        vector<int> iv(begin(arr), end(arr));
        restoreString(s, iv);
    }

    static void test2()
    {
        string s = "abc";
        int arr[] = {0,1,2};
        vector<int> iv(begin(arr), end(arr));
        restoreString(s, iv);
    }

    static void test3()
    {
        string s = "aaiougrt";
        int arr[] = {4,0,2,6,7,3,1,5};
        vector<int> iv(begin(arr), end(arr));
        restoreString(s, iv);
    }

    static void test4()
    {
        string s = "art";
        int arr[] = {1,0,2};
        vector<int> iv(begin(arr), end(arr));
        restoreString(s, iv);
    }
};

Solution::Solution(/* args */)
{
}

Solution::~Solution()
{
}

void Solution::restoreString(string& s, vector<int>& indices)
{
    cout<<s<<endl;
    for (auto c : indices)
        cout << c << ' ';
    cout << endl;

    if(s.length() != indices.size())
    {
        printf("error: s: %lu != %lu vector\n", s.length(), indices.size());
        return;
    }

    string t = s;

    for(size_t i = 0; i < s.length(); i++)
    {
        s[indices[i]] = t[i];
    }

    cout << s << endl << endl;
}

int main(int argc, char *argv[])
{
    Solution::test();
    return 0;
}

Fuzzing Embedded Linux Devices

Sun, 20 Dec 2020 18:30:08 +0800

This article is from a personal blog,Reprint please affirm

content

highlight

highlight

hello

git cherry-pick

Wed, 16 Dec 2020 08:30:38 +0800

This article is from a personal blog https://applelin8.github.io/2020/12/16/git-cherry-pick，Reprint please affirm

content

highlight
example

highlight

创建一个新分支,

#基于当前分支创建新分支
git checkout -b <new-branch-name>
#基于历史commit id创建分支
git checkout -b <new-branch-name> <SHA1>

checkout之前的一个commit并开一个branch指向它了.

在Git中创建分支，是必须有一个父节点的.默认是HEAd节点. git 场景：从一个分支cherry-pick多个commit

example

场景：

在branch1开发，进行多个提交，这时切换到branch2，想把之前branch1分支提交的commit都【复制】过来，怎么办？

创建分支branch2

查看所有分支

$ git branch -a
* branch1
  remotes/origin/HEAD -> origin/branch1
  remotes/origin/branch1
  remotes/origin/branch2

创建分支

## 切换分支 <span id="2.2">
git checkout remotes/origin/branch2

#创建新分支
git checkout -b branch2

查看分支

$ git branch -a
* branch2
  branch1
  remotes/origin/HEAD -> origin/branch1
  remotes/origin/branch1
  remotes/origin/branch2

首先切换到分支 branch1, 然后查看提交历史记录

# 切换分支
$ git checkout branch1
$ git branch 
* branch1
  branch2

git log

$find . -size +100M |grep -v git|xargs -I % ls -sh %
2.9G ./out/apple.iso
816M ./apple.tar

$ git  log --oneline  ./apple.tar
02a7492 add apple
$ git  log --oneline  ./out/apple.iso
8c3c7e0 apple iso
$ git log --oneline > log_sha.txt

切换到分支branch2

git checkout branch2

复制指定提交

cherry-pick用法

#复制单个commit
git cherry-pick <commitHash>
#复制多个commit
git cherry-pick <commitA_Hash> <commitB_Hash>
#复制多个连续commit 注意，不包含第一个commit0_Hash ， 即  git cherry-pick (commit0_Hash..commit100_Hash]
git cherry-pick <commit0_Hash>..<commit100_Hash>
#包含第一个commit0_Hash方法
git cherry-pick <commit0_Hash>^..<commit100_Hash>

用git cherry-pick复制

git cherry-pick 5396bf8^..8c3c7e0
rm -rf ./out/apple.iso
git add -u
git status
git commit --amend
git log --oneline

demo

#!/bin/bash
#set -vx
from=$1
to=$2
SCRIPT_PATH=$(readlink -f $(dirname $0))
file=${SCRIPT_PATH}/hash_git_log.txt
GIT_PATH=${SCRIPT_PATH}/demo

check_ret()
{
    ret=$?
    if [ $ret -ne 0 ]
    then
        echo [error] ret = $ret
        exit -1
    fi
}

is_stop_hash()
{
    hash=$1

    if [ "$hash" == "8c3c7e0" ]
    then
        echo [error] exit: 8c3c7e0
        exit
    fi
}

get_line_no()
{
    hash=$1
    ret=`awk '/'$hash'/{print NR}' $file`
    echo $ret
}

get_hash()
{
    line=$1
    hash=`echo $line|awk '{print $1}'`
    echo $hash
}

show_hash_line_no()
{
    hash=$1
    number=`get_line_no $hash`
    echo [info] $number : $hash
}

parse_line()
{
    line=$1
    hash=`echo $line|awk '{print $1}'`

    #discard "add linux 4.20 kernel"
    if [[ $line =~ "add linux 4.20 kernel" ]]
    then
        echo [warn] $line
        return
    fi

    show_hash_line_no $hash
    is_stop_hash $hash

    if [[ $line =~ "Merge" ]]
    then
        echo git cherry-pick -m 1 $hash
        git cherry-pick -m 1 $hash
        if [ $? -ne 0 ]
        then
            git reset --hard
            git clean -df
        fi
    else
        echo git cherry-pick $hash
        git cherry-pick $hash
        check_ret
    fi
}

read_file()
{
    number_from=`get_line_no $from`
    number_to=`get_line_no $to`
    sed -n ''$number_from','$number_to''p $file|while read line
    do
        echo ------------------------
        parse_line "$line"
    done
}

main()
{
    cd $GIT_PATH
    read_file
}

main

template blog

Wed, 16 Dec 2020 08:30:08 +0800

This article is from a personal blog https://applelin8.github.io/2020/12/16/template-blog，Reprint please affirm

content

highlight

highlight

hello

find by size

Wed, 16 Dec 2020 07:30:08 +0800

This article is from a personal blog https://applelin8.github.io/2020/12/16/find-by-size，Reprint please affirm

content

highlight

highlight

find [-H] [-L] [-P] [-Olevel] [-D help|tree|search|stat|rates|opt|exec|time] [path...] [expression]

查找当前目录下文件大小大于1M的文件

find ./ -type f -size +1M

查找当前目录下文件大小大于10M的文件,并显示它们的详细信息.

find . -size +10M -ls

搜索当前目录中，所有过去10分钟中更新过的普通文件。如果不加-type f参数，则搜索普通文件+特殊文件+目录。

 find . -type f -mmin -10

搜索当前目录中大于10M的文件,并显示详细信息.

find . -size +10M |xargs -I % ls -ahl %

linux ko

Tue, 15 Dec 2020 08:20:22 +0800

文章出自个人博客https://applelin8.github.io/2020/12/15/linux-ko，转载请申明

content

highlight
code
make

highlight

linux 系统ko模块编译。 note:

kernel dir
Makefile Kbuild Makefile 的一个最主要功能就是指定编译什么，这个功能是通过下面两个对象指定的obj-? 和$(module_name)-objs 例如：

   obj-y += example.o #编译o
   obj-m += $(module_name).o #编译ko
   $(module_name)-objs := a.o b.o c.o #编译基于的目标文件a.o b.o c.o

makefile的关键：

首先 obj-m指定模块名 $(module_name)，

   obj-m := $(module_name).o 

然后,

如果内核模块是通过几个源文件编译而成的,

再根据模块名$(name)-objs:=依赖的文件。

   $(module_name)-objs := a.o b.o c.o

Makefile example

   .PHONY: clean all

   #variable
   KDIR:=~/apple/kernel-4.15.4
   MAKE:=make
   name:=demo
   #$(info name=$(name))
   
   ifneq ($(KERNELRELEASE),)
   obj-m:=$(name).o
   $(name)-objs:= main.o hello.o
   endif
   
   #target
   all: demo
   
   demo:
   	#$(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules
   	$(MAKE) -C $(KDIR) M=$(PWD) modules
   	#sudo $(KDIR)/scripts/sign-file sha512 $(KDIR)/certs/signing_key.pem $(KDIR)/certs/signing_key.x509 $(name).ko
   	
   hello:
   	@echo hello
   
   clean:
   	$(MAKE) -C $(KDIR) M=$(PWD) clean

查看输出
```
dmesg | grep "keywords"
```

code

#ls demo
hello.c  hello.h  main.c  Makefile

hello.h

#ifndef _LINUX_HELLO_H_
#define _LINUX_HELLO_H_

void hello(void);

#endif

hello.c

#include "hello.h"
#include <linux/kernel.h>

void hello(void)
{
    printk("demo: hello\n");
    printk("demo: happy day!\n");
}

main.c

#include <linux/init.h>  
#include <linux/kernel.h>  
#include <linux/module.h> 
#include "hello.h"

static int demo_init(void)  
{  
    printk("demo: init module");
    hello();
    return 0;  
}  

static void demo_exit(void)  
{  
    printk("demo: exit module");  
    return;  
}  

module_init(demo_init);  
module_exit(demo_exit);  
MODULE_LICENSE("GPL");  
MODULE_AUTHOR("apple");

make

#cd demo
#make
make -C ~/apple/kernel-4.15.4 M=~/apple/project/module/demo modules
make[1]: Entering directory '~/apple/kernel-4.15.4'
  CC [M]  ~/apple/project/module/demo/main.o
  CC [M]  ~/apple/project/module/demo/hello.o
  LD [M]  ~/apple/project/module/demo/demo.o
  Building modules, stage 2.
  MODPOST 1 modules
  CC      ~/apple/project/module/demo/demo.mod.o
  LD [M]  ~/apple/project/module/demo/demo.ko
make[1]: Leaving directory '~/apple/kernel-4.15.4'

#ls ../demo
demo.ko  demo.mod.c  demo.mod.o  demo.o  hello.c  hello.h  hello.o  main.c  main.o  Makefile  modules.order  Module.symvers
#lsmod|grep demo
demo                   16384  0
#sudo rmmod demo
#sudo insmod demo.ko
#dmesg|grep demo
[ 2109.050790] demo: init module
[ 2109.050792] demo: hello
[ 2109.050793] demo: happy day!
#sudo rmmod demo
#dmesg|grep demo
[ 2123.678684] demo: exit module

make clean

#make clean
make -C ~/apple/kernel-4.15.4 M=~/apple/project/module/demo clean
make[1]: Entering directory '~/apple/kernel-4.15.4'
  CLEAN   ~/apple/project/module/demo/.tmp_versions
  CLEAN   ~/apple/project/module/demo/Module.symvers
make[1]: Leaving directory '~/apple/kernel-4.15.4'

makefile

Mon, 14 Dec 2020 18:20:22 +0800

文章出自个人博客https://applelin8.github.io/2020/12/14/makefile，转载请申明

content

makefile
make

makefile

PARAMETER

make PARAMETER=parameter

variable

var_a=a

target

target : depends

.PHONY: clean all
#PARAMETER ?= DBG
PARAMETER ?=

$(info PARAMETER=$(PARAMETER))
ifeq ($(PARAMETER), DBG)
CFLAGS += -DDBG_DEMO
endif

SRC_DIR = ./src
INC_DIR = ./include

DBG_DIR = ./debug

debug = demo_dbg
fuzzer = demo
CFLAGS += -I$(INC_DIR) -I./lib ${CFLAG}

all : $(fuzzer)

clean :
	rm -f $(fuzzer) demo_dbg $(SRC_DIR)/*.o $(DBG_DIR)/*.o

SRCS= $(wildcard $(SRC_DIR)/*.c)
OBJS= $(SRCS:.c=.o)

DBG_SRCS=$(wildcard $(DBG_DIR)/*.c) $(SRC_DIR)/abc.c
DBG_OBJS= $(DBG_SRCS:.c=.o)

$(OBJS) : lib/example.h

.c.o: $(CC) -c ./$(SRC_DIR)/$^ $(DBG_DIR)/$^ ${CFLAGS}

demo : $(OBJS)
	$(CC) $(CFLAGS) $^ -o $@

demo_dbg : $(DBG_OBJS)
	$(CC) $(CFLAGS) $^ -o $@

dbg : clean demo_dbg

make

make all

make

make dbg PARAMETER=DBG

make clean

make demo

valist

Mon, 14 Dec 2020 12:20:22 +0800

文章出自个人博客https://applelin8.github.io/2020/12/14/valist，转载请申明

content

valist
example

valist

如何获取函数的变长参数(va_list, va_start, va_arg, va_end) primer中讲得比较浅，提到了怎么声明怎么调用，但是没有写明在函数内部是如何获取变长参数。 1）省略号（ellipsis）

void fun1(int a, double b, …); //给出确定的几个参数，其他用省略号 void fun2(int a …) //省略号前有没有逗号都可以 void fun3(…) //也可以不确定任何参数，但与没参数是不一样的。

典型应用 printf:

int pritnf(const char *format, [, argument] …); //官方声明 printf(“My name is %s, age %d.”, “Apple”, 24); //调用

2）通用工作原理使用步骤：

a) 定义 va_list 变量ap b) va_start 初始化ap c) va_arg返回变长参数值。 d) va_end重置ap为NULLset

example

#include <stdio.h>
#include <stdarg.h>

#define __printf(a, b)	__attribute__((format(printf, a, b)))

#if 1
#define CHECK_FMT(a, b) __attribute__((format(printf, a, b)))
#else
#define CHECK_FMT(a, b)
#endif

void TRACE(const char *fmt, ...) CHECK_FMT(1, 2);

void TRACE(const char *fmt, ...)
{
    va_list ap;
    va_start(ap, fmt);  //va_start

    char ch;

    while(ch = *(fmt++)) //Iterate over the format string
    {
        if('%' == ch)
        {
            ch=*(fmt++);
            if(ch == 's')
            {
                char *str = va_arg(ap, char*); //va_arg
                printf("%s", str);
            }
            else if(ch == 'd')
            {
                int age = va_arg(ap, int); //va_arg
                printf("%d", age);
            }
        }
        else
        {
            printf("%c", ch);
        }
    }
    va_end(ap);
}

int main(void)
{
    TRACE("iValue = %d\n", 6);
    TRACE("iValue = %d\n", "test");

    return 0;
}

grub

Sun, 13 Dec 2020 12:30:16 +0800

文章出自个人博客https://applelin8.github.io/2020/12/13/grub，转载请申明

content

format
set

前置知识：你必须知道grub的启动过程以及bios和uefi的相关基础知识，可以参考：《Unified Extensible Firmware Interface Wikipedia》、《linux启动过程简介》

format

ls /boot/grub/
fonts  grub.cfg  grubenv  locale  unicode.pf2  x86_64-efi

grub.cfg

grub.cfg:这是grub的启动shell脚本，对于用户来说，是最重要的文件，几乎是用户配置grub的唯一的配置文件。通过这个文件用户可以控制grub加载操作系统的行为，比如添加一个menuentry就是添加一个操作系统启动选项，每个选项中可以指定操作系统内核镜像和initramfs镜像等等。

grub.cfg一般都不会手动编辑的，而是用过grub-mkconfig -o /boot/grub/grub.cfg去生成。

grubenv:预设的一些环境变量可以放到这，是一个文本文件.

grep -wn menuentry grub.cfg

/etc/default/grub

ls /etc/grub.d/
00_header  05_debian_theme  10_linux  20_linux_xen  20_memtest86+  30_os-prober  30_uefi-firmware  40_custom  41_custom  README

set

/etc/default/grub

GRUB_DEFAULT

设定预设的menu entry,可以是数字，或者是menu entry的标头，或是『saved』。

GRUB_DEFAULT="${submenu id}>${menu entry id}"

example

to set

GRUB_DEFAULT="gnulinux-advanced-c635a47d-c750-40a1-b647-54f27cacbb87>gnulinux-4.9.151abc-advanced-c635a47d-c750-40a1-b647-54f27cacbb87"

set

sudo sed -e 's/GRUB_DEFAULT/#GRUB_DEFAULT/g' -e '/GRUB_DEFAULT/i\GRUB_DEFAULT=0' -i /etc/default/grub
sudo sed -e '/GRUB_DEFAULT/d' -i /etc/default/grub

sudo sed -e '6i\GRUB_DEFAULT="gnulinux-advanced-c635a47d-c750-40a1-b647-54f27cacbb87>gnulinux-4.9.151abc-advanced-c635a47d-c750-40a1-b647-54f27cacbb87"' -i /etc/default/grub

grep -n GRUB_DEFAULT /etc/default/grub
6:GRUB_DEFAULT="gnulinux-advanced-c635a47d-c750-40a1-b647-54f27cacbb87>gnulinux-4.9.151abc-advanced-c635a47d-c750-40a1-b647-54f27cacbb87"

sudo update-grub
sudo reboot
uname -r
4.9.151abc

submenu

grep -n "gnulinux-advanced-c635a47d-c750-40a1-b647-54f27cacbb87" /boot/grub/grub.cfg 
19:   set default="gnulinux-advanced-c635a47d-c750-40a1-b647-54f27cacbb87>gnulinux-4.9.151abc-advanced-c635a47d-c750-40a1-b647-54f27cacbb87"
130:submenu 'Advanced options for Ubuntu' $menuentry_id_option 'gnulinux-advanced-c635a47d-c750-40a1-b647-54f27cacbb87' {

menu entry

grep -n "gnulinux-4.9.151abc-advanced-c635a47d-c750-40a1-b647-54f27cacbb87" /boot/grub/grub.cfg 
19:   set default="gnulinux-advanced-c635a47d-c750-40a1-b647-54f27cacbb87>gnulinux-4.9.151abc-advanced-c635a47d-c750-40a1-b647-54f27cacbb87"
635:	menuentry 'Ubuntu, with Linux 4.9.151abc' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.9.151abc-advanced-c635a47d-c750-40a1-b647-54f27cacbb87' {

vscode remote

Thu, 10 Dec 2020 08:06:16 +0800

文章出自个人博客https://applelin8.github.io/2020/12/10/vscode-remote，转载请申明

content

how to use vscode
extension
gdb
shell

how to use vscode

remote-ssh

C/C++ IntelliSense, debugging, and code browsing.

extension

gdb

${workspace}/.vscode/launch.json

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "gcc - 生成和调试活动文件",
            "type": "cppdbg",
            "request": "launch",
            "program": "${fileDirname}/${fileBasenameNoExtension}",
            "args": [ "ls"],
            "stopAtEntry": false,
            "cwd": "${workspaceFolder}",
            "environment": [],
            "externalConsole": false,
            "MIMode": "gdb",
            "setupCommands": [
                {
                    "description": "为 gdb 启用整齐打印",
                    "text": "-enable-pretty-printing",
                    "ignoreFailures": true
                }
            ],
            "preLaunchTask": "C/C++: gcc build active file",
            "miDebuggerPath": "/usr/bin/gdb"
        }
    ]
}

${workspace}/.vscode/tasks.json

{
    "tasks": [
        {
            "type": "shell",
            "label": "C/C++: gcc build active file",
            "command": "/usr/bin/gcc",
            "args": [
                "-g",
                "${file}",
                "-o",
                "${fileDirname}/${fileBasenameNoExtension}"
            ],
            "options": {
                "cwd": "${workspaceFolder}"
            },
            "problemMatcher": [
                "$gcc"
            ],
            "group": {
                "kind": "build",
                "isDefault": true
            }
        }
    ],
    "version": "2.0.0"
}

shell

git alias

Wed, 09 Dec 2020 12:06:28 +0800

文章出自个人博客https://applelin8.github.io/2020/12/9/git-alias，转载请申明

git cp = git cherry-pick

it.

it’s fine.

content

git alias

git-alias

[alias]
    co = checkout
    cob = checkout -b
    coo = !git fetch && git checkout
    br = branch
    brd = branch -d
    brD = branch -D
    merged = branch --merged
    st = status
    aa = add -A .
    cm = commit -m
    aacm = !git add -A . && git commit -m
    cp = cherry-pick
    amend = commit --amend -m
    dev = !git checkout dev && git pull origin dev 
    staging = !git checkout staging && git pull origin staging
    master = !git checkout master && git pull origin
    po = push origin
    pod = push origin dev 
    pos = push origin staging
    pom = push origin master
    poh = push origin HEAD
    pogm = !git push origin gh-pages && git checkout master && git pull origin master && git rebase gh-pages && git push origin master && git checkout gh-pages
    pomg = !git push origin master && git checkout gh-pages && git pull origin gh-pages && git rebase master && git push origin gh-pages && git checkout master
    plo = pull origin
    plod = pull origin dev 
    plos = pull origin staging
    plom = pull origin master
    ploh = pull origin HEAD
    unstage = reset --soft HEAD^
    ls = log --pretty=format:"%C(yellow)%h%Cred%d\\ %Creset%s%Cblue\\ [%cn]\\ %Creset%ad" --date=short  --decorate
    ll = log --pretty=format:"%C(yellow)%h%Cred%d\\ %Creset%s%Cblue\\ [%cn]" --decorate --numstat
    f = "!git ls-files | grep -i" 
    gr = grep -Ii 
    la = "!git config -l | grep alias | cut -c 7-"

pc of two net

Mon, 07 Dec 2020 12:06:28 +0800

文章出自个人博客，转载请申明

content

question
windows
linux

question

机器有两个网卡，一个是有线，另一个是无线。

pc1 ping pc2 有线不通。

ping 192.168.1.3

windows

route PRINT -4
===========================================================================
接口列表
4...66 66 66 66 66 66 ......Realtek PCIe GBE Family Controller
5...88 88 88 88 88 88 ......Qualcomm Atheros QCA9377 Wireless Network Adapter
===========================================================================

IPv4 路由表
===========================================================================
活动路由:
网络目标        网络掩码          网关       接口         跃点数
0.0.0.0       0.0.0.0  10.61.40.254   10.61.40.174    10
0.0.0.0       0.0.0.0  192.168.1.1    192.168.1.152   25
===========================================================================
永久路由:
  无

因为pc1的route设置无线的default route的跃点比有线的高，且没有192.168.1.3的路由，所以pc1 ping pc2的有线网卡不通。

增加路由：

#添加路由
route add 192.168.1.3 MASK 255.255.255.255  192.168.1.254 metric 30 if 4
#修改gateway和metric
route change 192.168.1.3 MASK 255.255.255.255  192.168.1.254 metric 5 if 4

设置规则(metric 越小，优先级越高)：

(192.168.1.3的metric) < (default 0.0.0.0  192.168.1.1) < (default 0.0.0.0 10.10.1.1)

linux

have nice day

# show route
ip r
route -n

# add route
route -p add 192.168.1.2 255.255.255.0 192.168.1.3

# ip route
ip route add default via 192.168.1.1 table 1
ip route add 192.168.0.0/24 via 192.168.1.2 table 1
#注:各路由表中应当指明默认路由,尽量不回查路由表.路由添加完毕,即可在路由规则中应用..

ip route add 192.168.1.0/24 dev eth0 via 192.168.1.66 realm 4

python main

Wed, 02 Dec 2020 12:06:28 +0800

文章出自个人博客https://applelin8.github.io/2020/12/2/python-main，转载请申明

content

main
read
numpy

main

Calculate the area of a circle

#const.py
PI = 3.14

def main():
    print("PI:", PI)

if __name__ == "__main__":
    main()
  

#area.py
from const import PI

def calc_circle_area(radius):
    return PI * (radius ** 2)
    
def main():
    print("circle area: ", calc_circle_area(2))
    
main()

read

# File: read.py

import sys
import re

def read_cmd(file, type):
    with open(file) as file:
        i=0
        for line in file:
            if line.find(type) != -1 and line.find(',') != -1:
                i+=1
                #print(line,end='')
                print(re.split(r'=| |,', line.strip())[0])
        print('cmd count is %d'%(i))


if __name__ == '__main__':
    file=sys.argv[1]
    type=sys.argv[2]
    
    print(file, type)
    read_cmd(file, type)

numpy

安装

python -m pip install numpy scipy matplotlib -i https://pypi.tuna.tsinghua.edu.cn/simple

python -m pip install pandas seaborn -i https://pypi.tuna.tsinghua.edu.cn/simple

画直方图v1

import sys
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns

sns.set()                                   #设置seaborn默认格式
np.random.seed(0)                           #设置随机种子数

from matplotlib.font_manager import FontProperties   #显示中文，并指定字体
myfont=FontProperties(fname=r'C:/Windows/Fonts/simhei.ttf',size=14)
sns.set(font=myfont.get_name())
plt.rcParams['axes.unicode_minus']=False      #显示负号

def draw(a, title="n"):
    #print(a);
    plt.rcParams['figure.figsize'] = (17, 8)    #设定图片大小
    f = plt.figure()                            #确定画布
    
    f.add_subplot(1,2,1)
    sns.distplot(a, kde=False)                 #绘制频数直方图
    #sns.distplot(a, kde=True,hist=True)                 #绘制频数直方图
    plt.ylabel("频数", fontsize=16)
    plt.xticks(fontsize=16)                    #设置x轴刻度值的字体大小
    plt.yticks(fontsize=16)                   #设置y轴刻度值的字体大小
    plt.title("("+ title + "个32位随机数分布图)", fontsize=20)             #设置子图标题
    
    f.add_subplot(1,2,2)
    sns.distplot(a)                           #绘制密度直方图
    plt.ylabel("密度", fontsize=16)
    plt.xticks(fontsize=16)                  #设置x轴刻度值的字体大小
    plt.yticks(fontsize=16)                  #设置y轴刻度值的字体大小
    
    plt.subplots_adjust(wspace=0.3)         #调整两幅子图的间距
    plt.show()
    
def draw_1000_number():
    a = np.random.randn(1000) 
    print(type(a))
    draw(a)
    
def draw_demo():
    #x = (1, 2 ,3 , 3, 4, 5 ,1)
    #x = (1, 2 ,3 , 3, 4, 5 ,1, 1, 1, 1, 1)
    #x = list(range(1,10))
    x = []
    for i in range(1,11):
        x.append(1)
    
    for i in range(1,6):
        x.append(10)
        
    a = np.asarray(x)
    print("a is : ",a);
    draw(a)

def draw_data(file):
    a = np.asarray([])
    count = 0
    with open(file) as file:
        for line in file:
            count += 1
            a = np.append(a,eval(line.strip()))
   
    print("number count=", count)
    #print(a)
    draw(a, str(count))

if __name__ == '__main__':
    draw_data(sys.argv[1])

画直方图v2

import sys
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns
from datetime import datetime

sns.set()                                   #设置seaborn默认格式
np.random.seed(0)                           #设置随机种子数

from matplotlib.font_manager import FontProperties   #显示中文，并指定字体
myfont=FontProperties(fname=r'C:/Windows/Fonts/simhei.ttf',size=14)
sns.set(font=myfont.get_name())
plt.rcParams['axes.unicode_minus']=False      #显示负号

oldtime=datetime.now()

def draw(a, title="n"):
    plt.rcParams['figure.figsize'] = (17, 8)    #设定图片大小
    f = plt.figure()                            #确定画布
    
    f.add_subplot(1,2,1)
    sns.distplot(a, kde=False)                 #绘制频数直方图
    #sns.distplot(a, kde=True,hist=True)                 #绘制频数直方图
    plt.ylabel("频数", fontsize=16)
    plt.xticks(fontsize=16)                    #设置x轴刻度值的字体大小
    plt.yticks(fontsize=16)                   #设置y轴刻度值的字体大小
    plt.title("("+ title + "个32位随机数分布图)", fontsize=20)             #设置子图标题
    
    f.add_subplot(1,2,2)
    sns.distplot(a)                           #绘制密度直方图
    plt.ylabel("密度", fontsize=16)
    plt.xticks(fontsize=16)                  #设置x轴刻度值的字体大小
    plt.yticks(fontsize=16)                  #设置y轴刻度值的字体大小
    
    plt.subplots_adjust(wspace=0.3)         #调整两幅子图的间距
    plt.show()

def delta_minute(startTime, endTime):
    total_seconds = (endTime - startTime).total_seconds()
    mins = total_seconds / 60
    return int(mins)
    
def get_diff_str(diff, str1):
    s = ''
    if diff != 0:
        s += str(diff) + str1
        
    return s

def show_delta(newtime):
    global oldtime
    s = '用时：'
    
    s += get_diff_str(delta_minute(oldtime, newtime), ' 分钟 ')
    s += get_diff_str((newtime-oldtime).seconds, ' 秒 ')
    s += get_diff_str((newtime-oldtime).microseconds / 1000, ' 毫秒 ')
    
    oldtime = newtime
    
    print(s)  

def show_array_info(a):
    print(a)  
    print("数据类型",type(a))           #打印数组数据类型  
    print("数组元素数据类型：",a.dtype) #打印数组元素数据类型  
    print("数组元素总数：",a.size)      #打印数组尺寸，即数组元素总数  
    print("数组形状：",a.shape)         #打印数组形状  
    print("数组的维度数目",a.ndim)      #打印数组的维度数目  
    
def iter_loadtxt(filename, delimiter=',', skiprows=0, dtype=float, len1=10000000):
    def iter_func():
        count=0
        with open(filename, 'r') as infile:
            for _ in range(skiprows):
                next(infile)
            for line in infile:
                line = line.rstrip().split(delimiter)
                for item in line:
                    yield dtype(eval(item))
                count += 1
                if count >= len1:
                    break
                
        iter_loadtxt.rowlength = len(line)

    data = np.fromiter(iter_func(), dtype=dtype)
    data = data.reshape((-1, iter_loadtxt.rowlength))
    return data

def draw_data1(file):
    a = np.loadtxt(file)
    draw(a, str(a.size))
    
def draw_data2(file):
    global oldtime
    
    print('-----------1 loadtxt --------------')
    oldtime=datetime.now()
    a = np.loadtxt(file)
    show_delta(datetime.now())
    
    print('-----------2 show array --------------')
    show_array_info(a)
    show_delta(datetime.now())
    
    print('-----------3 draw --------------')
    draw(a, str(a.size))
    show_delta(datetime.now())

def draw_data3(file):
    a = iter_loadtxt(file, '\n')
    draw(a, str(a.size))
    
def max_min_data(file):
    max = '0'
    min = '0xFFFFFFFF'
    count = 0
    with open(file, 'r') as f:
        for line in f:
            count += 1
            s = line.strip()
            x = eval(s)
            if x > eval(max):
                max = s
            if x < eval(min):
                min = s
            
            if count > 10000000:
                break
        
        print("max  : ", max)
        print("min  : ", min)
        print("count：", count)
    
if __name__ == '__main__':
    draw_data2(sys.argv[1])

结果

-----------1 loadtxt --------------
用时：0.999 毫秒 
-----------2 show array --------------
[1.81397318e+09 4.51097333e+08 7.47925723e+08 1.57521411e+09
 6.28680555e+08 2.98246167e+08 1.64331751e+09 2.06213070e+09]
数据类型 <class 'numpy.ndarray'>
数组元素数据类型： float64
数组元素总数： 8
数组形状： (8,)
数组的维度数目 1
用时：0.97 毫秒 
-----------3 draw --------------
用时：4 秒 549.668 毫秒 

说明：这里有list a=[1,1,1, …1, 10, 10,…，10]，list a有10个1和5个10，画了两幅直方图。其中左图是频数图，即纵坐标是频数，表示落在相应区间的样本数；右图是频率图，即纵坐标是概率，表示落在某区间的概率。

mount lvm

Fri, 27 Nov 2020 17:57:58 +0800

文章出自个人博客https://applelin8.github.io/2020/11/27/mount-lvm，转载请申明

content

mount lvm

vgscan

~$ sudo vgscan
  Reading all physical volumes.  This may take a while...
  Found volume group "centos" using metadata type lvm2
  

vgchange

~$ sudo vgchange -a y centos
  3 logical volume(s) in volume group "centos" now active

ls /dev/centos

~$ ls -ahl  /dev/centos/
总用量 0
drwxr-xr-x  2 root root  100 11月 27 10:55 .
drwxr-xr-x 20 root root 4.9K 11月 27 16:46 ..
lrwxrwxrwx  1 root root    7 11月 27 10:55 home -> ../dm-1
lrwxrwxrwx  1 root root    7 11月 27 10:55 root -> ../dm-2
lrwxrwxrwx  1 root root    7 11月 27 10:55 swap -> ../dm-0

mount lvm

mount_lvm.sh

#!/bin/bash                                                                                                                               
#set -xve
 
declare -a volume_groups
 
function get_volume_groups()
{
    id=0
    i=0 
    for line in $(sudo vgscan)
    do  
        eval result[$i]='$line'
        let i++ 
    done
 
    len=${#result[@]}
    for (( i=0;i<$len;i++))
    do  
        if [ ${result[$i]} == 'Found' ]
        then
            volume_groups[$id]=`echo ${result[$i+3]}|sed 's/\"//g'`
            let id++
            let i+=3
        fi  
    done
}
 
function mount_dir()
{
    volume_group=$1
    NR=$2
 
    dir=$(ls /dev/$volume_group/|awk "NR==$NR")
    echo mount dir : /opt/mnt/$volume_group/$dir
    sudo mkdir -p /opt/mnt/$volume_group/$dir
    sudo mount /dev/$volume_group/$dir /opt/mnt/$volume_group/$dir
}

function umount_dir()
{   
    volume_group=$1
    NR=$2
    
    dir=$(ls /dev/$volume_group/|awk "NR==$NR")
    echo umount dir : /opt/mnt/$volume_group/$dir
    sudo umount /opt/mnt/$volume_group/$dir
}   
    
function mount_volume_groups()
{   
    bool=$1
    for (( i=0;i<${#volume_groups[@]};i++ ))
    do
        echo $i: ${volume_groups[$i]}
        volume_group=${volume_groups[$i]}
        sudo vgchange -a y $volume_group
    
        dir_count=`ls /dev/$volume_group|sed -n '$='`
        for((j=1;j<$dir_count;j++))
        do
            if [ ${bool} == "y" ];then
                mount_dir $volume_group $j
            else
                umount_dir $volume_group $j
            fi
        done
    done
}   

function main()
{    
    get_volume_groups
    mount_volume_groups $1
}    
     
main $@

mount

mount_lvm.sh y

:~$ ls /opt/mnt/centos/home/
apple
:~$ ls /opt/mnt/centos/root/
bin  boot  dev	etc  home  lib	lib64  media  mnt  opt	proc  root  run  sbin  srv  sys  tmp  usr  var

tree

:~$ tree -L 2 /opt/mnt/centos/
/opt/mnt/centos/
├── home
│   └── apple
└── root
    ├── bin -> usr/bin
    ├── boot
    ├── dev
    ├── etc
    ├── home
    ├── lib -> usr/lib
    ├── lib64 -> usr/lib64
    ├── media
    ├── mnt
    ├── opt
    ├── proc
    ├── root
    ├── run
    ├── sbin -> usr/sbin
    ├── srv
    ├── sys
    ├── tmp
    ├── usr
    └── var

22 directories, 0 files

umount

mount_lvm.sh n

:~$ ls /opt/mnt/centos/home
:~$ ls /opt/mnt/centos/root

tree

:~$ tree -L 2 /opt/mnt/centos/
/opt/mnt/centos/
├── home
└── root

2 directories, 0 files

os process

Thu, 26 Nov 2020 12:30:28 +0800

文章出自个人博客https://applelin8.github.io/2020/11/26/os-process，转载请申明

content

os process
- what is process
Virtual memory
chosing an operation system
Virtual machine(VM)

os process

install Windows

install Linux

What’s process? <span id=”1.1>”

Process A program that’s executing,like our internet browser or text editor.

Program An application that we can run,like Chrome

Kernel Creates processes,efficiently schedules them,and manages how processes are terminated.

Time slice A very short interval of time that gets allocated to a process for CPU execution

Shell A program that interprets text commands and sends them to the OS to execute

Logs

Files that record system events on our computer,just like a system’s diary

The Boot Process

BIOS/UEFI A low-level software that initializes our computer’s hardware to makesure everything is good to go

Bootloader A small program that loads the operating system

As an IT Support Specialist, you’ ll install an operating system many times, so using one single disk won’t be time efficient or scalable.

Virtual memory

The combination of hard drive space and RAM that acts like memory that our processes can use

choosing an operation system

Virtual machine(VM)

Just a copy of a real machine virtual box

Memory
CPU
Storage

linux patch

Wed, 25 Nov 2020 16:44:52 +0800

文章出自个人博客https://applelin8.github.io/2020/11/25/linux-patch，转载请申明

What is patch?
- 简介
- patch文件格式
how to make patch
how to apply patch
- patch命令
- 应用

Introduce how to make and apply patch on linux?

What is patch?

简介

在linux下，修改了代码，为了方便分享（new feature）或者自己备份使用，一般需要制作一个补丁（patch）。

patch是一个文件两个版本之间的差异。

diff file.version1 file.version2 > file.patch

patch的作用是方便，组合灵活，体积小。

场景1

比如两个开发者A和B都有一project,

现在A在project中增加了新featureA,

如果B要用featureA，就不要整个把A的project的拿过来，如果project很大，这个会很花费拷贝时间和存储空间。

只要制作 featureA.patch, 然后B把featureA.patch的差异打到自己的project，就可以跟A的project的一样使用freatureA了。

freatureA.patch比project的体积小多了，方便分享和备份。

场景2

如果同一project, 多个开发人员A、B、C,

它们分别开发了 feature_A 、feature_B 、feature_C，

现在开发人员D，它也有project，他的需求可以是多样的，

D会只使用feature_A，

也许D会使用feature_B和feature_C而不要feature_A。

方便使用者根据需要组合使用patch。

patch文件格式

补丁文件内容到底是什么样子的？

例子

[patch_demo] $ cat to-file.patch 
--- from-file	2020-11-25 17:47:49.335233371 +0800
+++ to-file	2020-11-25 17:48:39.955230582 +0800
@@ -1,5 +1,6 @@
+aaa
 000
 111
-222
+bbb
 333
 444
[patch_demo] $ 

补丁头

补丁头分别由---和+++开头的两行，用来表示要打补丁的文件名。

---开头表示旧文件，

+++开头表示新文件

一个补丁文件中的多个补丁

一个补丁文件中可能包含以---和+++开头的很多节，每一节用来打一个补丁。所以一个patch文件中可以包含多个补丁。

块

块是补丁中要修改的地方。它通常由一部分不需要修改的内容开始和结束。他们只是表示用来修改的位置。他们通常以@@开始，结束于另一个块的开始或者一个新的补丁头。

块的缩进

块会缩进一列，并且这一列用来表示是要增加还是要删除的。

块的第一列

+号表示这一行是要加上的。-号表示这一行是要删除的。没有加号（+）也没有减号(-)表示这里只是引用的并不需要修改。

how to make patch?

diff 命令

制作补丁(patch)用到命令行比较工具 diff 。

diff 可以比较两个对象，并输出两者的区别。

diff 的用法：

diff [options] soure dest

-r 递归，比较目录下面（包含子目录）所有文件

-N 确保patch正确处理已经创建或删除文件的情况

-u 输出每个修改前后3行，也可以用-u5指定输出5行

-E, -b, -w, -B, –strip-trailing-cr 忽略各种空白，参考帮助，按需选用。

单文件补丁

产生单文件补丁

diff -uN from-file to-file >to-file.patch

因为是单个文件，所以不需要 -r 选项。

例子：

[patch_demo] $ ls
from-file  to-file
[patch_demo] $ cat from-file 
000
111
222
333
444
[patch_demo] $ cat to-file 
aaa
000
111
bbb
333
444
[patch_demo] $ diff -uN from-file to-file > to-file.patch

得到如下补丁

[patch_demo] $ cat to-file.patch 
--- from-file	2020-11-25 17:47:49.335233371 +0800
+++ to-file	2020-11-25 17:48:39.955230582 +0800
@@ -1,5 +1,6 @@
+aaa
 000
 111
-222
+bbb
 333
 444
[patch_demo] $ 

文件夹补丁

diff -uNr from-dir to-dir > to-dir.patch

例子

[dir] $ tree
.
├── from-dir
│   ├── a.txt
│   └── from.txt
└── to-dir
    ├── b.txt
    └── to.txt

2 directories, 4 files
[dir] $ cat from-dir/a.txt 
111
222
333111
[dir] $ cat from-dir/from.txt 
from
[dir] $ cat to-dir/b.txt 
aaa
b
c
[dir] $ cat to-dir/to.txt 
to
[dir] $ diff -uNr from-dir to-dir > to-dir.patch

得到如下补丁

[dir] $ cat to-dir.patch 
diff -uNr from-dir/a.txt to-dir/a.txt
--- from-dir/a.txt	2020-11-25 17:55:39.717207451 +0800
+++ to-dir/a.txt	1970-01-01 08:00:00.000000000 +0800
@@ -1,3 +0,0 @@
-111
-222
-333111
diff -uNr from-dir/b.txt to-dir/b.txt
--- from-dir/b.txt	1970-01-01 08:00:00.000000000 +0800
+++ to-dir/b.txt	2020-11-25 17:56:27.089204841 +0800
@@ -0,0 +1,3 @@
+aaa
+b
+c
diff -uNr from-dir/from.txt to-dir/from.txt
--- from-dir/from.txt	2020-11-25 17:56:07.124205941 +0800
+++ to-dir/from.txt	1970-01-01 08:00:00.000000000 +0800
@@ -1 +0,0 @@
-from
diff -uNr from-dir/to.txt to-dir/to.txt
--- from-dir/to.txt	1970-01-01 08:00:00.000000000 +0800
+++ to-dir/to.txt	2020-11-25 17:56:38.532204210 +0800
@@ -0,0 +1 @@
+to
[dir] $ 

how to apply patch?

patch命令

patch的作用是将diff输出的结果(补丁)应用到对就文件(夹)上。最常见的用法是：

patch -pNUM <patchfile>

-p NUM

忽略几层文件夹，随后详解。

-E

这个选项作用是如果发现空文件，就删除。

-R

取消打过的补丁。它是打补丁动作的逆操作。

为了解释-p参数，需要看一下如下patch文件片段：

--- old/modules/demo       2020-11-25 17:56:07.124205941 +0800
+++ new/modules/demo       2020-11-25 17:56:38.532204210 +0800

如果使用参数-p0,就表示从当前目录找一个叫做old的文件夹，再在它下面找modules/demo文件来执行patch操作。

而如果使用参数-p1，就表示忽略第一层目录(即不管old),从当前目录寻找modules的文件夹，再在它下面找demo。

应用

处理单个文件补丁的方法

# 产生补丁
diff -uN from-file to-file > to-file.patch

# 打补丁
patch -p0 < to-file.patch

# 取消补丁
patch -RE -p0 < to-file.patch

处理整个文件夹补丁的情况

# 产生补丁
diff -uNr  from-dir  to-dir  >to-dir.patch
 
# 打补丁
cd to-dir
patch -p1 < to-dir.patch
 
# 取消补丁
patch -R -p1 <to-dir.patch

Operation system

Wed, 25 Nov 2020 13:32:57 +0800

文章出自个人博客https://applelin8.github.io/2020/11/25/Operation-system，转载请申明

content

Operation system
- synopsis
- glossary

Operation system

What’s an operating system? Files and File Systems

synopsis

Operating system

The whole package that manages our computer’s resources and lets us interact with it

glossary

file system
Process management
Memory management

Our kernel optimizes memory usage and makes sure our applications have enough memory to run.

Host Machine
I/O management

input / output

Anything that can give us input,or that we can use for output of data

virtualization

Tue, 24 Nov 2020 20:59:49 +0800

文章出自个人博客https://applelin8.github.io/2020/11/24/virtualization，转载请申明

content

virtualization
- synopsis
- glossary

virtualization

synopsis

虚拟化技术的含义很广泛。 将任何一种形式的资源抽象成另一种形式的技术都是虚拟化。 在常用的操作系统中就存在某种意义上的“虚拟化技术”，例如虚拟内存空间和进程。

系统虚拟化是一门跨领域的学科，涉及操作系统、编译和体系结构等学科知识，并延展到资源管理、性能和系统安全等问题。

虚拟化技术分类。

典型系统级虚拟化的技术以及VMM的组成和分类。

基于软件的完全虚拟化技术。

硬件辅助的完全虚拟化技术。

类虚拟化技术的实现原理。

虚拟机的性能评测和调试技术。

系统虚拟化的应用实例。

对虚拟机和系统虚拟化技术的发展作一个展望。

glossary

Host

在虚拟化中，物理资源通常有一个定语称为宿主(Host)。

Host Machine

Host OS
Guest

虚拟出来的资源通常有一个定语称为客户（Guest）。

Guest Machine

Guest OS
硬件抽象层上的虚拟化

通常来说，宿主机和客户机的ISA（Instruction Set Architecture，指令集架构）是相同的,客户机的大部分指令可以在宿主处理器上直接运行。只有那些需要虚拟化的指令才会由虚拟化软件进行处理，
操作系统层上的虚拟化

操作系统层上的虚拟化是指操作系统的内核可以提供多个互相隔离的用户态实例。这些用户态实例（经常被称为容器）对于它的用户来说就像是一台真实的计算机，有自己独立的文件系统、网络、系统设置和库函数等。从某种意义上说，这种技术可以被认为是UNIX系统chroot命令的一种延伸。因为这是操作系统内核主动提供的虚拟化，因此操作系统层上的虚拟化通常非常高效，它的虚拟化资源和性能开销非常小，也不需要有硬件的特殊支持。但它的灵活性相对较小，每个容器中的操作系统通常必须是同一种操作系统。另外，操作系统层上的虚拟化虽然为用户态实例间提供了比较强的隔离性，但其粒度是比较粗的。因为操作系统层上虚拟化的高效性，它被大量应用在虚拟主机服务环境中。比较有名的操作系统级虚拟化解决方案有Paralles的Virtuozo，Solaris的Zone和Linux的VServer等。

IT

Sun, 22 Nov 2020 16:04:30 +0800

文章出自个人博客https://applelin8.github.io/2020/11/22/it，转载请申明

content

IT
- Information technology
Algorithm
Cryptography
GNU
- Open source
software
hardware
- Memory Controller Chip
- Motherboards
todo

Geek’s Lesson

you will learn the most basic of Information technology. No matter you are complete beginner or want to be IT professional, then this IT fundamental course is the right course for you to start. You will learn everything you need to know about IT. You will learn each and every basic of IT and develop strong skill and understanding of information technology.

IT

Information technology

What is information technology?

Information Technology(IT) The use of digital technology,like computers and the Internet,to store and process data into useful information

Algorithm

A series of steps that solve specific problems.

Cryptography

The art of writing and solving codes.

GNU

Open source

Anyone could modify and share it.

Operation System.

software

compiler was invented by Admiral Grace. Hopper compilers made it possible to translate human language via a program language into machine code in case you didn’t totally catch that we’ll talk more about compilers later. now learning programming languages is accessible for almost anyone anywhere. that scares you don’t worry we’ll help you every step of the way but for now let’s get back to the evolution of computers.

who knows what the future holds

computer language

0 + 1 = ?

simple math problem 0 plus 1 equals what?

Binary system The communication that a computer uses, also known as a base-2 numeral system. We group binary into 8 numbers or bits. Technically,a bit is a binary digit.

A group of 8 bits is referred to as a byte.

Each byte can store one character, and we can have 256 possible values thanks to the base-2 system(2^8).

01101000-h 01100101-e 01101100-I 01101111-o

computer talk this byte can mean something like the letter C and this is how a computer language is born

What does the following translate to?

01101000 01100101 01101100 01101100 01101111

something we’d be able to recognize what does the following translate.

make sure you understand the concept before moving on.

Character encoding

you can think of character encoding as a dictionary it’s a way for your computer’s to look up which human character should be represented by a given binary value.

The first character in the ASCll to binary table–a lowercase a -maps to 01100001 in binary.

RGB

that’s used in a lot of computers RGB or red green and blue model.

very cool

with just eight combinations of zeros and ones were able to represent everything that you see on your computer from a simple letter A to the very video that you’re watching right now.

Logic gates

we’ll discuss how we actually generate the zeros and ones.

Allow our transistors to do more complex tasks,like decide where to send electrical signals depending on logical conditions.

Digital Logic How to Count in Binary?

that you understand how computers count in binary we’ve shown you simple look-up tables that you can use like the ASCll to binary table.

you’ll need to know how binary works.

Decimal form : Base-10 system 0123456789

Computer Architecture Layer

Abstraction

To take a relatively complex system and simplify it for our use

error messages

hardware

The Modern Computer Intro to Computer Hardware

desktop

components

Ports Connection points that we can connect devices to that extend the functionality of our computer

CPU (Central Processing Unit) The brain of our computer,it does all the calculations and data processing

RAM (Random Access Memory) Our computer’s short-term memory

Hard drive Holds all of our data,which includes all of our music,pictures,applications

Motherboard The body or circulatory system of the computer that connects all the pieces together

computer can only communicate in binary using ones and zeros our computers

our computers speak in machine language but we of course speak in human languages like English Spanish Mandarin Hindi you get the idea if we want to communicate with our machines we have to have some sort of translation dictionary just like if I wanted to say something in Spanish.

well our computers have a built-in translation book.

Programs

Instructions that tell the computer what to do

1.Get two slices of bread. 2.Put peanut butter on one slice. 3.Put jelly on another slice. 4.Combine the two slices of bread.

on 1

off 0

Memory Controller Chip

MCC

Address bus

Cache

There are 3 different cache levels in a CPU: L1,L2, andL3.

L1is the smallest and fastest cache.

Clock wire

Calculations

Clock cycle

Clock speed

Clock speed The maximum number of clock cycles that it can handle in a certain time period

3.40 gigahertz is 3.4 billion cycles per second.

Overclocking

Adding Subtracting Copying data

instruction sets are hard-coded into out CPU.

Replacing failed hard disks Upgrading RAM modules Installing video cards

Intel AMD Qualcomm

Intel Corei7 AMD Athlon Snapdragon 810 AppleA8

When you select your CPU, you’ ll need to make sure it’s compatible with yourmotherboard–the circuit board that connects all your components together.

cpu socket

Land grid array(LGA) Pin grid array(PGA)

There are lots of types of RAM, and the one that’s commonly found in computers is DRAM, or dynamic random-access memory.

There are also different types of memorysticks that DRAM chips can be put on. The more modern DIMM sticks, which usuallystands for Dual Inline Memory Module, have different sizes of pins on them.

SDRAM

Synchronous DRAM

In today’s system, we use another type of RAM, called double data rate SDRAM or DDR SDRAM for short.

DDR1 DDR2 DDR3 DDR4

Motherboards

total boss

chipset

Northbridge

Southbridge

Peripherals

External devices we connect to ourcomputer,like a mouse,keyboard,and monitor

Expansion slots Give us the ability to increase the functionality of our computer

PCI Express

Peripheral Component Interconnect Express

Form factor

ATX

Advanced Technology eXtended

ITX

Information Technology eXtended

Storage

Data sizes

8bits 1 byte

1,024 bytes

Hard drive

Hard disk dives

HDD

RPM

Revolution per minute

Solid state drive

SSD

ATA

Serial ATA

SATA

NVM Express

NMe

Power Supplies

DC direct current

AC AC or alternating current

Information which is normally listed underneath or on the side.

cables

power cable

to understand electricy let’s use the example of water pipes.

the higher the pressure the more water there will be when it comes electricity we refer to the pressure as Voltage.

As a general rule, be sure to use the proper voltage for your electronics.

Amperage

AMPs

Wattage The amount of volts and amps that a device needs

You can power most basic desktops with a 500W power supply.

Peripherals

todo

Education Medicine Journalism Construction Transportation Entertainment Any industry

cpu knowledge

Sun, 22 Nov 2020 11:40:30 +0800

文章出自个人博客https://applelin8.github.io/2020/11/22/cpu，转载请申明

information

name

cpu is short of Central Processing Unit.

let’s remove the cover

cpu clock,

cpu do very complicate things very quick.

Intel cpu

But how do it know?

Book But How Do It Know

look under knees

Motherboad

register

Arithmetic Logic Unit (ALU)

Control Unit

todo

to be continued

clean code

Fri, 20 Nov 2020 21:03:56 +0800

文章出自个人博客https://applelin8.github.io/2020/11/20/clean-code，转载请申明

code

code noun

a set of instructions for a computer
a computer program,or a portion thereof
system of words,figures or symbols used to represent others,especially for the purposes of secrecy
a set of conventions or principles governing behaviour or activity in a particular domain

why

citation needed

NDC {London} 16-20 January 2017 Inspiring Software Developers since 2008

short name

choose right name

Clean Coders Hate What Happens to Your Code When You Use These Enterprise Programming Tricks

Refactoring (noun):a change made to the internal structure of software to make it easier to understand and cheaper to modify without changing its observable behavior. oR Kent Bit. Jolin lrnt Refactor(verb): to restructure software by applying a series of refactorings without changing the observable behavior of the software.

Singleton Configuration Singletons Verbose Naming Noisy Logging

Log And Throw

Repetition And Duplication

Unnecessary Code

Mixed Levels Of Abstraction

Legacy Coding Habits

Programming By Coincidence

Programming By Superstition

Kevlin Henney It is all to easy to dismiss problematic codebases on some nebulous idea of bad practice or bad programmers. Poor code, however, is rarely arbitrary and random in its structure or formulation. Systems of code, well or poorly structured, emerge from systems of practice, whether effective or ineffective. To improve code quality, it makes more sense to pick apart the specific practices and see their interplay — the cause — than to simply focus on the code itself — the effect. This talk looks at how a handful of coding habits, design practices and assumptions can systematically balloon code and compound its accidental complexity. NDC Conferences https://ndc-london.com https://ndcconferences.comNDC {London} 16-20 January 2017 Inspiring Software Developers since 2008

What if I told you Morpheus never says “What if I told you”?

Cargo cult programming is a style of computer programming characterized by the ritual inclusion of code or program structures that serve no real purpose. Cargo cult programming can also refer to the results of applying a design pattern or coding style blindly without understanding the reasons behind that design principle. http://en. wikipedia.org/wiki/Cargo_cult_programming

I have yet to see any problem, however complicated, which, when you looked at it in the right way, did not become still more complicated. Anderson’s Law

The default action is executed only if some previous actions were not executed. We ask if we can accomplish this without having to check the conditions for the previous actions twice; in other words, if we can make the control flow follow the information flow without loosing modularity. MaciejPirog “FizzBuzz in Haskell by Embedding a Domain-Specific Language”

A work of art is the unique result of a unique temperament. Oscar Wilde

Cargo cult programming is a style of computer programming characterized by the ritual inclusion of code or program structures that serve no real purpose. http://en.wikipedia.org/wiki/Cargo_cult programming

Signal-to-noise ratio(often abbreviated SNR or S/N) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. Signal-to-noise ratio is sometimes used informally to refer to the ratio of useful information to false or irrelevant data in a conversation or exchange. http/en. awikipedi. org/huiki/Signal_to_noise_ratio

To be,or not to be:that is the question: Whether ‘tis nobler in the mind to suffer The slings and arrows of outrageous fortune, Or to take arms against a sea of troubles, And by opposing end them? William Shakespeare Hamlet

Continuing existence or cessation of existence: those are the scenarios. Is it more empowering mentally to work towards an accommodation of the downsizings and negative outcomes of adversarial circumstance, or would it be agreater enhancement of the bottom line to move forwards to a challenge to our current difficulties, and, by making a commitment to opposition, to effect their demise? Tom Burton Long Words Bother Me

Comments A delicate matter, requiring taste and judgement.I tend to err on the side ofeliminating comments, for several reasons. First, if the code is clear, and uses good type names and variable names, it should explain itself. Second, comments aren’t checked by the compiler, so there is no guarantee they’ re right, especially after the code is modified.A misleading comment can be very confusing. Third, the issue of typography: comments clutter code. Rob Pike,”Notes on Programming in C”

I currently have an average of 15-25 imports in each source file, which is seriously making my code mixed-up and confusing. Is too many imports in your code a bad thing? Is there any way around this?

Avoid Long Import Lists by Using Wildcards Long lists of imports are daunting to the reader. We don’t want to clutter up the tops of our modules with 80 lines of imports. Rather wewant the imports to be a concise statement about which packages we collaborate with.

It is not a problem.Any IDE will manage imports and show them to you only when needed. Most IDEs support code folding where all the imports are folded down to one line.I rarely even see my imports these days as the IDE manages them and hides them as well.

Any good IDE, such as Eclipse, will collapse the imports in one line, and you can expand them when needed, so they won’t clutter your view.

http://stackoverflow. com/questions/8485689/too-many-imports-spamming-my-code

What is the Matrix? Control. The Matrix is a computer-generateddream world built to keep us undercontrol in order to change a human being into this.

A common fallacy is to assume authorsof incomprehensible code will somehowbe able to express themselves lucidly and clearly in comments. Kevlin Henney https://twitter.com/KevlinHenney/status/381021802941906944

ipmitool power control

Thu, 19 Nov 2020 22:21:36 +0800

文章出自个人博客https://applelin8.github.io/2020/11/19/ipmitool，转载请申明

power control

power status

ipmitool -H ${bmc_ip} -I lanplus -U ${bmc_username} -P ${bmc_pwd} power status

error

Error: Unable to establish IPMI v2 / RMCP+ session

on

Chassis Power is on
off

Chassis Power is off

power on

   ipmitool -H ${bmc_ip} -I lanplus -U ${bmc_username} -P ${bmc_pwd} power on

result

Chassis Power Control: Up/On

power off

   ipmitool -H ${bmc_ip} -I lanplus -U ${bmc_username} -P ${bmc_pwd} power off

result

Chassis Power Control: Down/Off

power reset

   ipmitool -H ${bmc_ip} -I lanplus -U ${bmc_username} -P ${bmc_pwd} power reset

result

Chassis Power Control: Reset

TEE

Thu, 19 Nov 2020 12:27:36 +0800

TEE

how to learn anything

Wed, 18 Nov 2020 00:00:00 +0800

how to learn anything

think out what would you like to learn?

4 simple steps to rapid skill acquisition

Deconstruct the skill
Learn enough to self-correct
Remove practice barries
Practice at least 20 hours

any questions have answers

Tue, 17 Nov 2020 00:00:00 +0800

#any questions have answers

你遇到的所有问题，都有答案。

不知道答案不要紧，寻找它。在书里，在生活里，在梦里，在错误里，在换角度思考里，在想象里，在变换角色里，真正安静地，没有干扰的，在心里体验之。在没有答案时，沉静，实验，多个思路，多个角度，多个维度来体验。一切定理定律，是在满足一定条件后才达到现在的效果和结果的。随机性到处都是,一个条件是对应一个结果，是一个随机性的必然性。
分不清答案是令人很困惑的，突破分清，会令人收获答案。

hello my post

Mon, 16 Nov 2020 00:00:00 +0800

文章出自个人博客https://applelin8.github.io/2020/11/16/hello，转载请申明

问题

hello

show hello

分析

how to show hello

解决方案

方法一

show hello.

by words. say. listen.

AppleLin的博客

ida demo

目录

问题

反汇编修改a > 0为n>0

用ida打开demo.exe.

IDA View-A

查看哪里调用 了”a > 0”

shuffle string

目录

问题

分析

解决方案

方法一

Fuzzing Embedded Linux Devices

content

highlight

git cherry-pick

content

highlight

example

场景：

创建分支branch2

首先切换到分支 branch1, 然后查看提交历史记录

切换到分支branch2

复制指定提交

demo

template blog

content

highlight

find by size

content

highlight

linux ko

content

highlight

code

make

makefile

content

makefile

make

valist

content

valist

example

grub

content

format

set

GRUB_DEFAULT

example

vscode remote

content

how to use vscode

extension

gdb

shell

git alias

content

git-alias

pc of two net

content

question

windows

linux

python main

content

main

read

numpy

画直方图v1

画直方图v2

mount lvm

content

mount lvm

os process

content

os process

What’s process? <span id=”1.1>”

查看哪里调用了”a > 0”