git init .

   git clone --depth=1 https://...

   git add --all 
   git commit -m "sth"

   git pull

   git push origin master

   git config --global http.proxy http://proxy.mycompany:80

   git config --global core.quotepath false

   git config --global core.editor "vim"

   git lfs track "*.png"
   git lfs track "*.jpg"
   git lfs track "*.jpeg"
   git lfs track "*.gif"

   git lfs track "*.mp4"
   git lfs track "*.mpeg"
   git lfs track "*.mkv"

   pdftk C:\Users\Sid\Desktop\doc.pdf dump_data output C:\Users\Sid\Desktop\doc_data.txt

   pdftk C:\Users\Sid\Desktop\doc.pdf update_info C:\Users\Sid\Desktop\doc_data.txt output C:\Users\Sid\Desktop\updated.pdf

   BookmarkBegin
   BookmarkTitle: PDF Reference (Version 1.5)
   BookmarkLevel: 1
   BookmarkPageNumber: 1
   BookmarkBegin
   BookmarkTitle: Contents
   BookmarkLevel: 2
   BookmarkPageNumber: 3

   u"阿斯顿".encode('ascii', 'xmlcharrefreplace')

   def utf8_to_ascii_xml(filename):
       with open(filename,'r',encoding='utf-8') as fi:
           lines = fi.readlines()
           lines_ascii = [x.encode('ascii', 'xmlcharrefreplace') for x in lines]
       with open(f"{filename}.ascii", 'wb') as fi:
           fi.writelines(lines_ascii)

   # import
   import pytesseract
   from PIL import Image
   import numpy as np
   import pandas as pd
   import re

   # 利用 OCR 生成目录
   print(pytesseract.image_to_string(Image.open('a.png')))

   # 手动编辑目录，使用 orgmode 的表格
   data = pd.read_csv("a.txt", sep="|")
   darr = np.array(data)
   darr[:,1] = [i.strip() for i in darr[:,1]]
   darr[:,2] = [i.strip() for i in darr[:,2]]
   darr[2:,3] = darr[2:,3]+9
   data = pd.DataFrame(darr[:,1:-1])
   data

   # 生成目录格式并保存
   block = """BookmarkBegin
   BookmarkTitle: {title}
   BookmarkLevel: {level}
   BookmarkPageNumber: {page}
   """
   txt = ""
   for line in darr:
       index = line[1]
       title = line[2]
       page = line[3]
       if index == '' or index[-1] == '.':
           level = 1
       else:
           level = 2
           txt += block.format(title=f"{index} {title}", level=level, page=page)

   with open("b.txt",'w') as fi:
       fi.writelines(txt)

   ssh-keygen -t rsa

   touch ~/.ssh/authorized_keys
   chmod 600 ~/.ssh/authorized_keys
   cat ~/.ssh/a_rsa.pub >> ~/.ssh/authorized_keys

   ssh username@localhost

   # 查看系统所有安装的服务项
   systemctl list-unit-files --type=service

   # 查看系统所有运行的服务项
   systemctl list-units --type=service

   # 查看系统所有开机自启动的服务项
   systemctl list-unit-files --type=service | grep enabled

   # 查看指定服务项状态
   systemctl status <服务项名称>

   # 查看服务项的依赖关系
   systemctl list-dependencies <服务项名称>

   # 查看系统启动耗时
   systemd-analyze

   # 查看各项服务启动耗时
   systemd-analyze blame | grep .service

   # 启动服务
   systemctl start <服务项名称>

   # 停止服务
   systemctl stop <服务项名称>

   # 重启服务
   systemctl restart <服务项名称>

   # 重新读取配置文件
   # 如果该服务不能重启，但又必须使用新的配置，这条命令会很有用
   systemctl reload <服务项名称>

   # 使服务开机自启动
   systemctl enable <服务项名称>

   # 使服务不要开机自启动
   systemctl disable <服务项名称>

   # 禁用服务
   # 这可以防止服务被其他服务间接启动，也无法通过 start 或 restart 命令来启动服务。
   systemctl mask <服务项名称>

   # 不再禁用服务
   systemctl unmask <服务项名称>

   # 重新读取所有服务项
   # 修改、添加、删除服务项之后需要执行以下命令。
   systemctl daemon-reload

   [Unit]
   Description=My Startup

   [Service]
   Type=simple
   ExecStart=/path/to/server --server

   [Install]
   WantedBy=multi-user.target

   # start jupyter lab
   [Unit]
   Description=jupyter lab
   After=nginx.target

   [Service]
   Type=simple
   Environment="PATH='/home/username/.local/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games'" "PYTHONPATH='/home/username/.local/bin:/usr/lib/python39.zip:/usr/lib/python3.9:/usr/lib/python3.9/lib-dynload:/home/username/.local/lib/python3.9/site-packages:/usr/local/lib/python3.9/dist-packages:/usr/lib/python3/dist-packages:/home/username/.local/lib/python3.9/site-packages/IPython/extensions:/home/username/.ipython'"
   ExecStart=/home/username/.local/bin/jupyter lab --LabApp.app_dir=/home/username/.local/share/jupyter/lab --notebook-dir=/home/username/Projects --allow-root --config=/home/username/.jupyter/jupyter_lab_config.py

   [Install]
   WantedBy=multi-user.target

   [Unit]
   Description=mount 

   [Mount]
   What=/dev/sdb1
   Where=/mnt/sds
   Options=defaults

   [Install]
   WantedBy=local-fs.target

   apt install samba

   # 创建 smb 的组
   /usr/sbin/addgroup smbgroup
   # 把用户加到组里
   /usr/sbin/usermod -aG smbgroup mylocaluser
   # 设置用户的远程密码，可以与本地登录密码不同
   smbpasswd -a mylocaluser

   cp /etc/samba/smb.conf /etc/samba/smb.conf.backup

   [global]

   # 允许用户登录
   security = user

   [homes]

   read only = no

   [newport]
   path = /path/to/files
   valid users = @smbgroup
   guest ok = no
   writable = yes
   browsable = yes

date +"%F %T UTC%:z"

#+BEGIN_COMMENT
.. title: nikola: static site generator
.. slug: nikola-static-site-generator
.. date: 2020-12-19 15:19:12 UTC+08:00
.. tags: python, blog
.. category: tools
.. link: 
.. description: 
.. type: text
.. has_math: true

#+END_COMMENT

blog here.

   "metadata": {
     "nikola": {
      "title": "Power Method for Eigenvalues",
      "slug": "power-method-for-eigenvalues",
      "date": "2020-12-19 15:20:52 UTC+08:00",
      "tags": "Numerical Algorithm,Linear Algebra",
      "category": "Algorithm",
      "link": "",
      "description": "",
      "type": "text"
     }
   }