const 发布的文章

“const”

0.ubuntu 20.04 安装 minicom 工具

sudo apt install minicom

1.启动工具,连接串口

minicom -D /dev/ttyUSB0

2.修改默认配置,关闭Hardware Flow Control
先按Ctrl+A组合键,然后松开这两个键,再按Z键。再按O, 出现配置菜单.
按F键

F - Hardware Flow Control : No

记得保存退出.

1、查看curl与时间相关的选项

curl -h |grep time

有用的输出

--connect-timeout <seconds> Maximum time allowed for connection
--expect100-timeout <seconds> How long to wait for 100-continue
--keepalive-time <seconds> Interval time for keepalive probes
-m, --max-time <seconds> Maximum time allowed for the transfer
-y, --speed-time <seconds> Trigger 'speed-limit' abort after this time

2、控制连接超时--connect-timeout 5

curl -v --connect-timeout 1 https://const.net.cn

当出现连接超时时,会提示如下信息

curl: (28) Connection timed out after 1001 milliseconds

3、总超时时间--max-time
 我们希望curl程序在运行一段时间后,不管有没有执行完成都能正常退出。就用这个max-time

curl -v -m 60 https://const.net.cn

4、--speed-time 的用法
speed-time是用来根据速率来控制连接是否断开的。
用法:

curl -o const.log "https://const.net.cn" --speed-time 5 --speed-limit 1

是说将url内容保存到const.log中, 如果传输速度小于1字节/秒的状态持续5秒,该连接就会断开,并退出程序。

1、使用默认的 归档管理器 打开
使用提取到此处功能,如果可以就不用其他办法了。
有时候会不哪么好使,会提示错误。
2、安装rar

sudo apt install rar
sudo apt install unrar

3、解压使用 rar x file.rar
示例:

rar x "孙露《2021最新专辑·再远的远方》.rar"

输出:

RAR 5.50 Copyright (c) 1993-2017 Alexander Roshal 11 Aug 2017
Trial version Type 'rar -?' for help

Extracting from 孙露《2021最新专辑·再远的远方》.rar

Creating 孙露《2021最新专辑·再远的远方》[WAV分轨]
OK Extracting 孙露《2021最新专辑·再远的远方》[WAV分轨]/01.孙露 - 再远的远方.wav
OK Extracting 孙露《2021最新专辑·再远的远方》[WAV分轨]/02.孙露 - 迷人月光.wav
OK Extracting 孙露《2021最新专辑·再远的远方》[WAV分轨]/03.孙露 - 心软.wav
OK Extracting 孙露《2021最新专辑·再远的远方》[WAV分轨]/04.孙露 - 不忘.wav
OK Extracting 孙露《2021最新专辑·再远的远方》[WAV分轨]/05.孙露 - 你敢不敢.wav
OK Extracting 孙露《2021最新专辑·再远的远方》[WAV分轨]/06.孙露 - 好好爱自己.wav
OK Extracting 孙露《2021最新专辑·再远的远方》[WAV分轨]/07.孙露 - 破晓.wav
OK Extracting 孙露《2021最新专辑·再远的远方》[WAV分轨]/08.孙露 - 呓语.wav
OK Extracting 孙露《2021最新专辑·再远的远方》[WAV分轨]/09.孙露 - 眼泪会说谎.wav
OK Extracting 孙露《2021最新专辑·再远的远方》[WAV分轨]/10.孙露 - 爱的太假.wav
OK Extracting 孙露《2021最新专辑·再远的远方》[WAV分轨]/Cover.jpg
OK

1、curl -w参数

curl -h |grep "write-out"

-w, --write-out <format> Use output FORMAT after completion

2、显示所有时间示例

curl -o /dev/null -s -w "time_namelookup:%{time_namelookup}\ntime_connect: %{time_connect}\ntime_starttransfer: %{time_starttransfer}\ntime_total: %{time_total}\n"  "https://const.net.cn/"

输出:

time_namelookup:0.058759
time_connect: 0.069912
time_starttransfer: 0.147355
time_total: 0.167685

3、参数说明

time_namelookup: DNS 服务器域名解析的时间(以上时间单位都是s)
time_connect: client 发出请求,到 c/s 建立TCP 的时间;里面包括 DNS 解析的时间
time_starttransfer: client 发出请求;到 server 响应发出第一个字节开始的时间;包括前面的2个时间
time_total: 从请求发起到链接关闭的总耗时

4、官方英文说明

time_appconnect: The time, in seconds, it took from the start until the SSL/SSH/etc connect/handshake to the remote host was completed. (Added in 7.19.0)
time_connect: The time, in seconds, it took from the start until the TCP connect to the remote host (or proxy) was completed.
time_namelookup: The time, in seconds, it took from the start until the name resolving was completed.
time_pretransfer: The time, in seconds, it took from the start until the file transfer was just about to begin. This includes all pre-transfer commands and negotiations that are specific to the particular protocol(s) involved.
time_redirect: The time, in seconds, it took for all redirection steps including name lookup, connect, pretransfer and transfer before the final transaction was started. time_redirect shows the complete execution time for multiple redirections. (Added in 7.12.3)
time_starttransfer: The time, in seconds, it took from the start until the first byte was just about to be transferred. This includes time_pretransfer and also the time the server needed to calculate the result.
time_total: The total time, in seconds, that the full operation lasted.

5、格式可以使用字符串,格式化文件以及标准输入

The format can be specified as a literal "string", or you can have curl read the format from a file with "@filename" and to tell curl to read the format from stdin you write "@-".

6、使用格式文件示例

cat curl-format.txt

   time_namelookup:%{time_namelookup}\n
      time_connect:%{time_connect}\n
   time_appconnect:%{time_appconnect}\n
     time_redirect:%{time_redirect}\n    
  time_pretransfer:%{time_pretransfer}\n  
time_starttransfer:%{time_starttransfer}\n
------------------------------\n
        time_total:  %{time_total}\n

使用示例:

curl -o /dev/null -s -w "@curl-format.txt"  "https://const.net.cn/"

输出结果:

   time_namelookup:0.165160
      time_connect:0.240436
   time_appconnect:0.326137
     time_redirect:0.000000
  time_pretransfer:0.326211
time_starttransfer:0.412927
------------------------------
        time_total:  0.486244

1、需要使用到的go-sqlite 的 github地址

https://github.com/mattn/go-sqlite3

2、安装go-sqlite

go get github.com/mattn/go-sqlite3

提示:
Important: because this is a CGO enabled package you are required to set the environment variable CGO_ENABLED=1 and have a gcc compile present within your path.

3、示例代码

package main

import (
    "database/sql"
    "fmt"
    "log"
    "os"

    _ "github.com/mattn/go-sqlite3"
)

func main() {
    os.Remove("./foo.db")

    db, err := sql.Open("sqlite3", "./foo.db")
    if err != nil {
        log.Fatal(err)
    }
    defer db.Close()

    sqlStmt := `
    create table foo (id integer not null primary key, name text);
    delete from foo;
    `
    _, err = db.Exec(sqlStmt)
    if err != nil {
        log.Printf("%q: %s\n", err, sqlStmt)
        return
    }

    tx, err := db.Begin()
    if err != nil {
        log.Fatal(err)
    }
    stmt, err := tx.Prepare("insert into foo(id, name) values(?, ?)")
    if err != nil {
        log.Fatal(err)
    }
    defer stmt.Close()
    for i := 0; i < 10; i++ {
        _, err = stmt.Exec(i, fmt.Sprintf("https://const.net.cn %03d", i))
        if err != nil {
            log.Fatal(err)
        }
    }
    tx.Commit()

    rows, err := db.Query("select id, name from foo")
    if err != nil {
        log.Fatal(err)
    }
    defer rows.Close()
    for rows.Next() {
        var id int
        var name string
        err = rows.Scan(&id, &name)
        if err != nil {
            log.Fatal(err)
        }
        fmt.Println(id, name)
    }
    err = rows.Err()
    if err != nil {
        log.Fatal(err)
    }

    stmt, err = db.Prepare("select name from foo where id = ?")
    if err != nil {
        log.Fatal(err)
    }
    defer stmt.Close()
    var name string
    err = stmt.QueryRow("3").Scan(&name)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println(name)

    _, err = db.Exec("delete from foo")
    if err != nil {
        log.Fatal(err)
    }

    _, err = db.Exec("insert into foo(id, name) values(1, 'const'), (2, 'net'), (3, 'cn')")
    if err != nil {
        log.Fatal(err)
    }

    rows, err = db.Query("select id, name from foo")
    if err != nil {
        log.Fatal(err)
    }
    defer rows.Close()
    for rows.Next() {
        var id int
        var name string
        err = rows.Scan(&id, &name)
        if err != nil {
            log.Fatal(err)
        }
        fmt.Println(id, name)
    }
    err = rows.Err()
    if err != nil {
        log.Fatal(err)
    }
}

4、编译运行

CGO_ENABLED=1 GOOS=linux go run .

运行结果:

0 https://const.net.cn 000
1 https://const.net.cn 001
2 https://const.net.cn 002
3 https://const.net.cn 003
4 https://const.net.cn 004
5 https://const.net.cn 005
6 https://const.net.cn 006
7 https://const.net.cn 007
8 https://const.net.cn 008
9 https://const.net.cn 009
https://const.net.cn 003
1 const
2 net
3 cn

5、go sqlite3 arm64/aarch64

env CC=aarch64-linux-gnu-gcc CXX=aarch64-linux-gnu-g++  CGO_ENABLED=1 GOOS=linux GOARCH=arm64 GOARM=7  go build -v