* find . -name "*.sty"
  * lsof | less : list open files, more information with fuser
  * rpm -qil --whatprovides --provides php
  * dpkg -L paketname : list files installed by paketname; more see AptDpkg
  * id : gives not only username but uid+guids
  * uname -a : gives all system informations like hardware,software
  * less file.txt : pressing v in less mode enters vi
  * ssh-keygen -l -f /etc/ssh/ssh_host_rsa_key.pub : gives fingerprint of my system written into ~/.ssh/known_hosts
  * typing CRTL+A jumps to the beginning of the shell line
  * visudo : change /etc/sudoers
  * echo $PATH : ask values of variable PATH