技术总结

Linux Small Tools

Posted by Bryan on August 22, 2017

install vim

sudo apt-get install vim

renew a file called .vimrc:

set nu
set confirm
set mouse=a
set tabstop=4
set cindent
syntax on

In insert mode, other clipboard content could add to vim with CTRL-V. At this time, the format or indent could be messed up.
Inputting =G in normal mode could or may solve the problem. The first view of openning vim is normal mode.
Inputting : will enter command mode. The V can enter Visual mode, alse i is insert mode.

Shortcut for vim editor:

  1. Search/Replace:
    /pattern search fo pattern
    ?pattern search backward for pattern
    :%s/old/new/g replace old with new throughout file
    :%s/old/new/gc replace old with new throughout file with confirmation
  2. Working with multiple files:
    :e filename edit a file in a new buffer
    :bn go to next buffer
    :bp go to previous buffer
    :bd delete a buffer(close a file)
    :ls list all buffers
    :sp filename open a file in a new buffer and split window
    :vsp filename open a file in a new buffer and split window vertically
    ctrl + ww switch windows
    ctrl + wq quit a window

install terminator

sudo apt-get install terminator
sudo apt-get install dconf-tools
gsettings set org.gnome.desktop.default-applications.terminal exec   /usr/bin/terminator
gsettings set org.gnome.desktop.default-applications.terminal exec-arg "-x"

快捷键使用 Ctrl+Shift+O Split terminals Horizontally.（上下开新窗口） Ctrl+Shift+E Split terminals Vertically.（垂直开新窗口）

Jupyter Notebook

  • 安装
pip install --upgrade pip # upgrade pip to the newest version
pip install jupyter
  • 配置
jupyter notebook --generate-config #如/home/inin下没有.jupyter file
jupyter notebook password ##设置密码
jupyter notebook ##启动notebook

打开浏览器 输入127.0.0.1:8888 输入密码

blog native compile

准备工作，参考下列教程：

部署自己的博客：Github+Jekyll

Provide Answers to Questions

Install jekyll on Ubuntu

sudo apt-get install ruby ruby-dev make
sudo gem install jekyll --no-rdoc --no-ri
sudo apt-get install nodejs    

jekyll build -w
jekyll serve

  • Solve the problem that gem install jekyll error: Reference to stack exchange

  • Use mathjax: Follow the link

  • Use table of content: I use the tutorial of the link.

ssh登录

被登录计算机安装
sudo apt-get install openssh-server

进行登录的计算机
ssh <user_name>@<host_ip>

网络下载工具 wget

wget [参数] [URL地址]

Advantage： 1. 支持断点续传 2. 支持代理服务器 3. 支持FTP和HTTP下载 4. 程序小，完全免费

下载参数：

–spider  测试下载速度
-c, –continue 接着下载没下载完的文件
–bind-address=ADDRESS 指定本地使用地址(主机名或IP，当本地有多个IP或名字时使用)
-Y, –proxy=on/off 打开或关闭代理
–limit-rate=RATE 限定下载输率
-r, –recursive 递归下载(real entire website)
-l, –level=NUMBER 最大递归深度 (inf 或 0 代表无穷)

At this time, we can use wget to download the entire website with command:

$ wget \
     --recursive \
     --no-clobber \
     --page-requisites \
     --html-extension \
     --convert-links \
     --restrict-file-names=windows \
     --domains website.org \
     --no-parent \
         www.website.org/tutorials/html/

The options are:

  • – recursive: download the entire Web site.
  • – domains website.org: don’t follow links outside website.org.
  • –no-parent: don’t follow links outside the directory tutorials/html/.
  • –page-requisites: get all the elements that compose the page (images, CSS and so on).
  • –html-extension: save files with the .html extension.
  • –convert-links: convert links so that they work locally, off-line.
  • –restrict-file-names=windows: modify filenames so that they will work in Windows as well.
  • –no-clobber: don’t overwrite any existing files (used in case the download is interrupted and resumed).

Docker CE install and use on Ubuntu

$ sudo apt-get update

$ sudo apt-get install \
    linux-image-extra-$(uname -r) \
    linux-image-extra-virtual

$ sudo apt-get update

$ sudo apt-get install \
    apt-transport-https \
    ca-certificates \
    curl \
    software-properties-common

$ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

$ sudo apt-key fingerprint 0EBFCD88



$ sudo add-apt-repository \
   "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
   $(lsb_release -cs) \
   stable"

$ sudo apt-get update

$ sudo apt-get install docker-ce

$ sudo docker run hello-world

可以简单使用docker

docker run -d -P seqvence/static-site
docker ps

打开网页localhost:docker ip映射到80的端口

virtualenv虚拟环境

virtualenv(python2) and venv(python3) is a tool to create isolated Python environments.

installation

$ pip install virtualenv
$ apt-get install python3-venv

Usage

  • Virtualenv has one basic command:
python2 -m virtualenv ENV // mkdir a dir called ENV in inputting command dir
python3 -m venv ENV
  • ENV/lib/ and ENV/include/ are created, containing supporting library files for a new virtualenv python.

  • Packages installed in this environment will live under ENV/lib/pythonX.X/site-packages/.

  • There is a script used to activate virtualenv

On Posix systems, this resides in /ENV/bin/, so you can run:

$ source bin/activate

This will change your $PATH so its first entry is the virtualenv’s bin/ directory. (You have to use source because it changes your shell environment in-place.) This is all it does.
To undo these changes to your path (and prompt), just run:deactivate.

The –system-site-packages Option

If you build with virtualenv --system-site-packages ENV, your virtual environment will inherit packages from /usr/lib/python2.7/site-packages (or wherever your global site-packages directory is). If you want isolation from the global system, do not use this flag.

Use Systemctl to manage Systemd Services and Units

Systemctl is used on ubuntu 16.04 not ubuntu 14.04

Introduction: Systemd is an init system and system manager that is becoming the new standard for Linux.

1. Starting and Stopping services

sudo systemctl start <application>.service
sudo systemctl start application  //systemd knows to look for *.service* files
sudo systemctl stop <application>.service

2. Enabling and Disabling Services

enable命令这将使某服务在系统启动时候就被自动start

sudo systemctl enable <application>.service

以上会创建一个软连接from服务文件（/lib/systemd/system or /etc/systemd/system）into systemd寻找的地方（/etc/systemd/system/some_target.target.wants）

sudo systemctl disable <application>.service

以上将移除软连接，服务将不会自动启动

{Note} Enalbing a service does not start in the current session.

3. Checking the status of Services

systemctl status <application>.service
systemctl is-active <app>.service //输出是否
systemctl is-enabled <app>.service //输出是否

Switch nvidia and intel Graphic card

sudo prime-select nvidia/intel
sudo reboot # if needed

sudo/su/root

sudo means superuser do and su means switch user.
su will switch current user to root and su bryan will switch current suer to bryan. su -root will not only switch to root but switch current env to new user’s env.
sudo will give root privilege temperory. And sudo -i means loginning with root privilege.

➜  ~ pwd
/home/bryan
➜  ~ sudo -i
[sudo] password for bryan: 
root@bryan-5810:~# pwd
/root

tcpdump

Capturing packets with tcpdump

To begin, use the command tcpdump -D to see which interfaces are available for capture:

$ sudo tcpdump -D
1.eth0
2.virbr0
3.eth1
4.lo
5.any (Psudo-device that captures on all interfaces)

Understanding the output format

08:41:13.729687 IP 192.168.64.28.22 > 192.168.64.1.41916: Flags [P.], seq 196:568, ack 1, win 309, options [nop,nop,TS val 117964079 ecr 816509256], length 372

The first field, 08:41:13.729687, represents the timestamp of the received packet as per the local clock.
Next, IP represents the network layer protocol—in this case, IPv4. For IPv6 packets, the value is IP6.
The next field, 192.168.64.28.22, is the source IP address and port. This is followed by the destination IP address and port, represented by 192.168.64.1.41916. The next field, 192.168.64.28.22, is the source IP address and port. This is followed by the destination IP address and port, represented by 192.168.64.1.41916.
Next is the sequence number of the data contained in the packet. For the first packet captured, this is an absolute number. Subsequent packets use a relative number to make it easier to follow. In this example, the sequence is seq 196:568, which means this packet contains bytes 196 to 568 of this flow. Finally we have the packet length, length 372.

play pcap

tcpdump -nn -r webserver.pcap

save pcap

tcpdump -s 65535 host 54.204.39.132 port 80 -i eth0 -w my.pcap

search a package derived from apt

apt-cache search pcl to check all package including pcl in name. Use apt-cache policy libpcl-dev to check if install the package and its version.

Likely you can use ldconfig -p| grep pcl to print its cache to check if the library is installed in system.

Donation

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