G9SAj

      4th law of thermodynamics*:

      Complexity is multiplicative 
      Rob Pike

      *) https://en.wikipedia.org/wiki/Laws_of_thermodynamics

Cherchez la femme
-----------------

Console

  find
  locate
  which
  whereis
  grep
  mc
  scripts and pipes
  apt-cache search
  apt-file search
  dpkg (-l -L)

GUI

  local search: gnome, xfce

Internet

  google, bing,..
  ftpsearch
  finger
  ..

find
....

  http://www.tecmint.com/35-practical-examples-of-linux-find-command/
  
  Find Last 50-100 Days Modified Files:
    find / -mtime +50 -mtime -100
  Find Specific Files and Delete:
    find / -type f -name *.mp3 -size +10M -exec rm {} \;
    
apt-cache search
................

  # apt-cache search desktop | grep '\(u\|e\)\-desktop' | grep '[a-z]*ubuntu'
  
  ubuntu-desktop - The Ubuntu desktop system
  edubuntu-desktop - educational desktop for Ubuntu
  kubuntu-desktop - Kubuntu Plasma Desktop/Netbook system
  lubuntu-desktop - Lubuntu Desktop environment
  qtubuntu-desktop - Qt plugins for Ubuntu Platform API (desktop)
  ubuntu-desktop-mir - System compositor for Ubuntu Desktop
  ubuntu-gnome-desktop - The Ubuntu GNOME metapackage
  ubuntu-mate-desktop - Ubuntu MATE - full desktop
  xubuntu-desktop - Xubuntu desktop system
  
  http://www.omgubuntu.co.uk/2016/05/install-gnome-3-20-ubuntu-16-04-lts

Install GNOME 3.20 on Ubuntu 16.04 LTS
......................................

  sudo add-apt-repository ppa:gnome3-team/gnome3-staging
  sudo add-apt-repository ppa:gnome3-team/gnome3
  sudo apt update
  sudo apt dist-upgrade
  sudo apt install gnome gnome-shell
  apt-get remove unity
  apt-get autoremove
  apt-get install ubuntu-gnome-desktop
  
  *gdm3
   lightdm
   
or (if forgotten)

  # dpkg-reconfigure gdm3
  # service lightdm stop
  
or (if systemctl)

  # systemctl service stop lightdm
  # systemctl service start gdm

Read also:

  1. http://askubuntu.com/questions/766071/install-gnome-shell-on-ubuntu-16-04
  2. http://askubuntu.com/questions/152256/how-do-i-switch-from-lightdm-to-gdm
  
apt-file
........

  # apt-get install apt-file
  # apt-file update
  # apt-file find kwallet.h
  kdelibs5-dev: /usr/include/kwallet.h
  libkf5wallet-dev: /usr/include/KF5/KWallet/kwallet.h

