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Category: Linux运维

Linux,unix,mysql,database,oracle,mysql

VMware性能优化

VMware Player里安装的虚拟机一般都特别卡(即使你的物理机配置很高), 原因是VMware默认设定在本地生成一个swap文件来当作虚拟机的内存(这能不卡吗??), 本文介绍一些优化参数.

将以下选择写入到你的.vmx文件中(仅适用Windows物理机)

MemTrimRate = "0" 
mainMem.useNamedFile = "FALSE"
sched.mem.pshare.enable = "FALSE" 
prefvmx.useRecommendedLockedMemSize = "TRUE"
prefvmx.minVmMemPct = "100"

如果你的物理机是Linux而不是Windows则需要用如下选项代替上面的mainMem.useNamedFile = “FALSE”

mainmem.backing = "swap"

参考文档
Windows 7 kills VMWare performance by disk caching?

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remove pCloud Drive on Ubuntu/Debian

Remove pCloud Drive on Ubuntu/Debian system.

1, remove autostart from Tweaks Tool
2, run command 

killall pcloud
\rm -rf ~/.pcloud
\rm -rf ~/.local/share/applications/appimagekit-pcloud.desktop
\rm -rf /tmp/.mount_pcloud*
\rm -rf /tmp/pcloud_unix_soc.sock

3, reboot.

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iptables delete some rules form a chain

以下两条命令均可用

iptables -t nat -L PREROUTING --line-numbers | grep RULE_NAME | cut -d" " -f 1 | xargs iptables -t nat -D PREROUTING

for i in $(iptables -t nat -nvL PREROUTING --line-numbers | grep RULE_NAME | grep ^[0-9] | awk '{ print $1 }' | tac); do iptables -t nat -D PREROUTING $i; done
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How to run a crontab job every X seconds

如果你有一个job, 需要每隔5秒运行一次.

以下写法是错误的

* * * * * sleep 5; /bin/cmd

如果使用这种写法, 会导致在每分钟的第0秒开始, sleep 5秒以后, 再运行/bin/cmd, 然尔运行完就结束了, 不会每隔5秒运行一次.

正确写法1

* * * * * for i in {1..12}; do /bin/cmd; sleep 5; done

正确写法2

* * * * * REMAIN=60 INC=5 ; while ; do /bin/cmd; sleep $INC; REMAIN=$(($REMAIN - $INC)); done

正确写法3

* * * * * /bin/cmd
* * * * * sleep 5; /bin/cmd
* * * * * sleep 10; /bin/cmd
* * * * * sleep 15; /bin/cmd
......
* * * * * sleep 55; /bin/cmd

可以使用systemctl status cron.service -l命令看看cron服务的状态以及最新日志.

参考: How to run a cronjob every X seconds in cron

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docker基础知识(一)

安装docker

# 适用ubuntu 16.04
$ sudo apt install docker docker.io

# 适用CentOS 7 (这部分文档来自Docker官方https://docs.docker.com/install/linux/docker-ce/centos/)
$ yum install -y yum-utils device-mapper-persistent-data lvm2    # 安装依赖
$ yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
$ yum install docker-ce docker-ce-cli containerd.io
$ systemctl start docker

一,images管理
搜索kms相关的image

$ sudo docker search kms
NAME                                         DESCRIPTION                                     STARS     OFFICIAL   AUTOMATED
luodaoyi/kms-server                          kms server                                      21                   [OK]
lunker/kms                                   ubuntu image repositoiry for kms                1                    
leon0516/py-kms                              this is beta version!!!                         1                    [OK]
captbrick/py-kms                             Py-KMS                                          1                    [OK]
gkuzet/kms                                   KMS Server written in C                         1                    
openvidu/openvidu-server-kms                 OpenVidu platform service. It includes Ope...   1

比如第1个luodaoyi/kms-server,也可以用https://hub.docker.com/r/luodaoyi/kms-server/的方式查看相关信息.

下载想要的image(不必需)

$ sudo docker pull luodaoyi/kms-server

查看本地的images

$ sudo docker images
REPOSITORY            TAG                 IMAGE ID            CREATED             SIZE
luodaoyi/kms-server   latest              4f86d964ac52        4 months ago        4.09 MB

$ sudo docker image ls
REPOSITORY            TAG                 IMAGE ID            CREATED             SIZE
luodaoyi/kms-server   latest              4f86d964ac52        4 months ago        4.09 MB
Continue readingdocker基础知识(一)
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