Did You Know: Chapter 2

September 27, 2017
tld cmd linux tgz

  1. In the Soviet era Russia your land could be transferred to others by the state and hence was not private property.
  2. The .COM TLD was one of the first created in 1985
  3. Root name servers
    1. There are 13 root name server around the world operated by 12 independent organisations
    2. Each name server starts with [name].root-servers.net, with name replaced with any of chars including [a-m]
    3. Even though there are 13 root name servers, each of the 13 organisations that maintain these servers deploys multiple physical servers around the globe
    4. This basically means, there is load balancer for each root name server before all the physical servers deployed in different locations
    5. Infrastructure TLDs: .ARPA, mostly used for reverse DNS lookups.
  4. International charges to credit-card accounts are cleared per country basis. And charges made in different countries are reconciled periodically. Thus bank balance can be different in different countries
  5. DNA remains in the nucleus, while RNA can enter the far reaches of the cell to carry out DNA’s instructions.
  6. readlink -f file.txt will fetch the full path of file.txt
  7. List contents of tar gz and fetch only one file
    1. Tar tf file.tgz
    2. Tar-xf file.tgz filename
  8. Nice trace route - mtr google.com
  9. Print text ad infinitum
    1. yes prints yes infinitely
    2. yes hello prints hello infinitely
  10. w prints who is logged in
  11. ls | nl prepends line number
  12. tac file backwards of cat prints from end to start
  13. Run a command everytime file is modified
    1. while inotifywait -e close_write document.tex;do;make;done
  14. Keep program running after leaving ssh
    1. Nohup ./program &
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