Editing Text Images (section)

===UNIX===
* it was '''time-sharing''' system, allowing for mutiples users to login to the machine <code>ssh username@machineIP</code>
* included the '''shell:''' a program which performs command line interpretation  
** <code>whoaim</code> 
** <code>pwd</code> '''p'''rint '''w'''orking '''d'''irectory - where am I?
** <code>date</code>
** <code>users</code> print the user names of users currently logged in to the current host
** <code>history</code> commands' history
* tree-structured file system 
** <code>tree ~/</code> list contents of home (~ == /home/username ) in a tree-like format 
** <code>ls ~</code> list files and directories in your user home ( ~ == /home/username )  
** <code>ls .</code> list files and directories in current directory ( . == current dir )  
** <code>ls ../</code> list files and directories in parent directory ( . == current dir )  
** <code>ls foo/</code> list files and directories in child foo/ directory 
** <code>ls /</code> list files and directories in root ( / == root ) 
* every thing is a file
** <code>ls -R / > /dev/dsp </code> file-system as sound 
Others emerged from the development and use of the system and crystallized  into the ''Unix Philosophy'':
* '''Write programs that do one thing and one thing well''' 
** <code>ls</code> lists files in a directory 
** <code>cat</code> outputs content of file 
** <code>wc</code> counts number of words in file 
* '''Write programs that work together''' 
** <code>echo "hello UNIX world" | sed 's/o/0/g' | sed 's/e/3/g' | sed 's/l/1/g' | figlet</code>
* '''Write programs that handle text streams, because that is a universal interface''' 
** <code>man -a intro | espeak</code> Linux introduction to user commands.