• apt tool
• fontconfig
• ssh login without password
  http://www.linuxproblem.org/art_9.html
  https://www.tecmint.com/ssh-passwordless-login-using-ssh-keygen-in-5-easy-steps/
• how to use scp
  https://twpower.github.io/138-send-file-using-scp-command

Linux/BSD 초급

• grep
• ln -s
• Ubuntu, Debian, OpenBSD directory hierarchy
  https://en.wikipedia.org/wiki/Unix_filesystem#Conventional_directory_layout
  https://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard