C#

1. To exit the environment(or console dialog), the followings will work, according to this
   You can use Environment.Exit(0); and Application.Exit.
   
2. 
   

Regular Expression

1. To search for unicode character sets used in certain languages, one can use \p properties, i.e. perluniprops. Such as the following to search for a part of strings composed Arabic letters and/or spaces.
   grep '[\s\p{Arabic}]*'
   https://perldoc.perl.org/perluniprops.html#Properties-accessible-through-%5cp%7b%7d-and-%5cP%7b%7d
2. 
   

linux commands

1. To find which partition is mounted where, use findmnt:
   findmnt /dev/sda1
2. To mount, use mount, to unmount use umount.
3. To list all mount disk, "mount -l".
4. To check file systems
   https://www.tecmint.com/find-linux-filesystem-type/
5. To make partitions and format and mount, see
   http://www.nemotos.net/?p=3132
6. 
   

Wiktionary

• Parsing raw compressed dump file. Example to extract the title of all pages().
  bzcat pages-articles.xml.bz2 | grep '<title>[^[:space:][:punct:]]*</title>' | sed 's:.*<title>\(.*\)</title>.*:\1:'
  https://stackoverflow.com/questions/3364279/has-anyone-parsed-wiktionary/9735019
• Regular expression which include unicode characters. For instance if Arabic,
  ^[\p{Arabic}\s\p{N}]+$
  https://stackoverflow.com/questions/29729391/regular-expression-arabic-characters-and-numbers-only

BeautifulSoup

1. To check if an object is of NavigableString instance, one can use
   isinstance(your_obj, bs4.element.NavigableString)
2. file method executed as a member function of a tag object fails. https://en.wikipedia.org/wiki/Duck_typing
3. To download image from its url:
   import shutil; import requests
   url = 'http://example.com/img.png'
   response = requests.get(url, stream=True)
   with open('img.png', 'wb') as out_file:
       shutil.copyfileobj(response.raw, out_file)
   del response
   https://stackoverflow.com/questions/13137817/how-to-download-image-using-requests