技术

mysql备忘录

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密码问题

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#/etc/my.cnf
[mysqld]
skip-grant-tables=1
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FLUSH privileges;
ALTER USER 'root'@'localhost' IDENTIFIED BY 'admin@123';

重启

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systemctl restart mysqld

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException:
Could not create connection to database server. Attempted reconnect 3

https://www.cnblogs.com/ianhuafeng/p/12403626.html
https://zhuanlan.zhihu.com/p/632935077

Install MySql in Windows, download zip file from https://dev.mysql.com/downloads/windows/installer/5.7.html

mysqld --initialize --console
mysqld --install mysql
net stop mysql
mysqld --skip-grant-tables
	mysql -u root -p
		use mysql;
		select * from user;
		update user set authentication_string=password("123456") where user="root";
		flush privileges;
net start mysql

refer to:
https://www.cnblogs.com/huaisn/articles/14149356.html

comparing ubuntu with centos in package management

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yum

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# find which package the cmd 'a.out' belongs to
yum provides */bin/a.out
# check if 'wget' package is installed
yum list installed | grep wget
# download 'wget' package to /tmp/rpm/
yum install yum-plugin-downloadonly
yum download --downloaddir=/tmp/rpm/ --downloadonly wget
# list all files in 'wget' package
rpm -qlp /tmp/rpm/wget*.rpm
# another method listing files without downloading
yum install yum-utils
repoquery -l wget

apt

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# find which package 'Python.h' belongs to
apt install apt-file
apt-file update
apt-file search Python.h
# list all files in 'wget' package
dpkg -L wget

package names

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  ubuntu			  centos
install build-essential		groupinstall "Development tools"
xfce4				@xfce-desktop
ssh				openssh-clients
udev				systemd-udev
libc6-dev			glibc-devel
libglib2.0-dev			glib2-devel
libffi-dev			libffi-devel
libncurses5			ncurses
libncurses5-dev			ncurses-devel
libsqlite3-dev			sqlite-devel
libnet1-dev			libnet-devel
libreadline6			readline
bridge-utils			bridge-utils
libpcre3-dev			pcre-devel
libyaml-dev			libyaml-devel
libmagic-dev			file-devel
liblua5.1-0-dev			lua-devel
libssl-dev			openssl-devel
zlib1g-dev			zlib-devel
lm-sensors			lm_sensors
ifenslave			iputils
ntpdate				ntp
redis-server			redis
libperl-dev			perl-devel
libjpeg-turbo8-dev		libjpeg-turbo-devel
libfreetype6-dev		freetype-devel
iproute2			iproute
iputils-ping			iputils
ifupdown			NetworkManager
net-tools			net-tools
libpython3.8-dev		python3-devel
mysql-server			mysql5-server
libmysqlclient-dev		mysql5-devel
tofrodos			dos2unix
				kernel-headers
				kernel-devel
qemu-user-static
initramfs-tools
gcc-5-plugin-dev
build-essential
libprelude-dev
libzmq3-dev
libhtp-dev
fbset				maybe in xorg-x11-server

deprecated in ubuntu

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sysv-rc-conf
libjpeg-dev # why?

refer to:
https://blog.csdn.net/mimosa2008/article/details/102833837
https://forums.centos.org/viewtopic.php?t=14711
https://blog.csdn.net/xldwhj/article/details/72831674
https://www.cnblogs.com/orcl-2018/p/13276558.html
https://blog.csdn.net/HAOMCU/article/details/7268687
https://mirrors.tuna.tsinghua.edu.cn/help/fedora/

switch between shell and anaconda in serial console

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as are indicated at the bottom of the console, there are 5 windows in anaconda, we can toggle any of them by press:

<Ctrl> + <b> + <window number>

in a tmux style.

refer to:
https://docs.centos.org/en-US/centos/install-guide/Trouble-x86/
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/installation_guide/sect-consoles-logs-during-installation-x86

automatic disk performance test

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mkdir like test_case1, copy three files below in it:

test_case1/test.py

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#!/bin/python3
import os
 
def shell_run(name, cmd):
	os.system('mkdir result')
	os.system(cmd + '> ./result/' + name)
 
def run_cmds(cmds):
	for name, cmd in cmds.items():
		shell_run(name, cmd)
 
cmds = {
	'1_small_read'		: 'fio -name iops -rw=read -bs=4k -runtime=60 -iodepth 32 -filename /dev/sda6 -ioengine libaio -direct=1',
	'1_small_randread'	: 'fio -name iops -rw=randread -bs=4k -runtime=60 -iodepth 32 -filename /dev/sda6 -ioengine libaio -direct=1',
	'1_small_write'		: 'fio -name iops -rw=write -bs=4k -runtime=60 -iodepth 32 -filename /dev/sda6 -ioengine libaio -direct=1',
	'1_small_randwrite'	: 'fio -name iops -rw=randwrite -bs=4k -runtime=60 -iodepth 32 -filename /dev/sda6 -ioengine libaio -direct=1',
	'1_big_read'		: 'fio -name iops -rw=read -bs=10M -runtime=60 -iodepth 32 -filename /dev/sda6 -ioengine libaio -direct=1',
	'1_big_randread'	: 'fio -name iops -rw=randread -bs=10M -runtime=60 -iodepth 32 -filename /dev/sda6 -ioengine libaio -direct=1',
	'1_big_write'		: 'fio -name iops -rw=write -bs=10M -runtime=60 -iodepth 32 -filename /dev/sda6 -ioengine libaio -direct=1',
	'1_big_randwrite'	: 'fio -name iops -rw=randwrite -bs=10M -runtime=60 -iodepth 32 -filename /dev/sda6 -ioengine libaio -direct=1',
	'4_small_read'		: 'fio -name iops -rw=read -bs=4k -runtime=60 -iodepth 32 -filename /dev/sda6 -ioengine libaio -direct=1 -numjobs=4',
	'4_small_randread'	: 'fio -name iops -rw=randread -bs=4k -runtime=60 -iodepth 32 -filename /dev/sda6 -ioengine libaio -direct=1 -numjobs=4',
	'4_small_write'		: 'fio -name iops -rw=write -bs=4k -runtime=60 -iodepth 32 -filename /dev/sda6 -ioengine libaio -direct=1 -numjobs=4',
	'4_small_randwrite'	: 'fio -name iops -rw=randwrite -bs=4k -runtime=60 -iodepth 32 -filename /dev/sda6 -ioengine libaio -direct=1 -numjobs=4',
	'4_big_read'		: 'fio -name iops -rw=read -bs=10M -runtime=60 -iodepth 32 -filename /dev/sda6 -ioengine libaio -direct=1 -numjobs=4',
	'4_big_randread'	: 'fio -name iops -rw=randread -bs=10M -runtime=60 -iodepth 32 -filename /dev/sda6 -ioengine libaio -direct=1 -numjobs=4',
	'4_big_write'		: 'fio -name iops -rw=write -bs=10M -runtime=60 -iodepth 32 -filename /dev/sda6 -ioengine libaio -direct=1 -numjobs=4',
	'4_big_randwrite'	: 'fio -name iops -rw=randwrite -bs=10M -runtime=60 -iodepth 32 -filename /dev/sda6 -ioengine libaio -direct=1 -numjobs=4'
}
run_cmds(cmds)

test_case1/parse.cpp

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how to turn off fans in linux

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after running 'sensors-detect' command, kernel modules controlling fan speed should be loaded.

here is an occasion with 'Nuvoton NCT6102D/NCT6104D/NCT6106D Super IO Sensors' detected.

as nct6775 document said:

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#/sys/class/hwmon/hwmon4
pwm[1-7]
    - this file stores PWM duty cycle or DC value (fan speed) in range:
	   0 (lowest speed) to 255 (full)
 
pwm[1-7]_enable
    - this file controls mode of fan/temperature control:
	* 0 Fan control disabled (fans set to maximum speed)
	* 1 Manual mode, write to pwm[0-5] any value 0-255
	* 2 "Thermal Cruise" mode
	* 3 "Fan Speed Cruise" mode
	* 4 "Smart Fan III" mode (NCT6775F only)
	* 5 "Smart Fan IV" mode
...

ps1. if set pwm[1-7]_enable to 0, we will not be able to change it to other value, unless reboot linux.
ps2. I still can't find a common way to turn off fans using ipmitool.

IPMI: Intelligent Platform Management Interface
BMC: Baseboard Management Controller
FRU: Field Replaceable Unit

refer to:
[linux-kernel-src-root]/Documentation/hwmon/nct6775.rst
https://bbs.archlinux.org/viewtopic.php?id=225349

AF-1020 ipsec

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问题一：第三方对接都配置好了，实时抓包却未见AF-1020发isakmp或esp包。
1，第一阶段里要配线路出口，网络接口要选对接口并指定同样的线路出口。
2，VPN接口设置里要选择另一个网络接口为内网接口。
3，线路出口对应的网络接口与内网对应的网络接口不能相同网段。
问题二：第一阶段过后不进行第二阶段。
有可能在第二阶段设置中，出站策略与入站策略的源IP子网相同了。
问题三：同一个连接中无法生成多个ESP通道。
比如，同一个连接对应的第二阶段设置中，出站策略两个，入站策略两个，在AF-1020主动发起quick mode协商时，会一股脑儿向对端发2X2=4个esp sa isakmp包。
但根据ike协议的要求，每个包取hash需要的iv是放在ike sa的上下文中，这样其中3个esp sa isakmp包会被对端认为hash payload不正确而被抛弃。
而AF-1020 DLAN运行状态中却显示第二个通信连接成功了，其实是个BUG。
但是AF-1020在被动quick mode协商中，可以正确生成多个ESP通道。

refer to:
http://blog.itpub.net/81227/viewspace-2670399/

成为上帝玩转Chrome禁止图片显示

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比如禁止微信公众号里的文章显示图片，经F12分析，图片来源为包含两种字符串的网址：

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mmbiz.qpic.cn/mmbiz
mmbiz.qlogo.cn/mmbiz

把这两个字符串分两条规则加到BlockSitePlugin插件的strFrom里，strTo都置空，再在Chrome设置中的历史记录里，清空图片缓存，这点很重要。

之后刷新微信公众号文章，图片就没有了。

再比如禁止今日头条网页版顶部动画，在BlockSitePlugin插件的strFrom里输入

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lf3-static.bytednsdoc.com/obj/eden-cn/upqlnvhj

strTo置空，加入此规则，并清空所有历史记录，由于这个动画是mp4，要重启Chrome，之后才能看到动画消失。

refer to:
成为上帝玩转Chrome之指定阻止访问的网站