,        ,         
               /(        )`        
               \ \___   / |        
               /- _  `-/  '        
              (/\/ \ \   /\        
              / /   | `    \       
              O O   ) /    |       
              `-^--'`<     '       
             (_.)  _  )   /        
              `.___/`    /         
                `-----' / 
######################################
PIPES
######################################
Unix programs have three channels of
Communication (pipes)

Standard Input : The source of
information. Data being brought in,
from your keyboard, network, a file, a
program, or any other source.

Standard Output : Where the programs
output is displayed. Your console,
network, a file, another program, etc

Standard Error : Where the program
sends its error messages. Error
messages tend to get returned to the
console or a log file. They could also
be (miss)configured to be dropped.

######################################
These three pipes arranged any way you
wish. You could send your errors to a
file. If a command is long, you can
put that info into a file and dump it
into standard input. Or you can pipe
(send) the output of one command
directly into the 2nd.

example : standard input comes from
the keyboard to type the command. The
output of the "cat" command is then
piped into the "grep" command.
_____________________________________
cat passwd | grep -i user
_____________________________________
   <----.     __ / __   \          
   <----|====O)))==) \) /====|      
   <----'    `--' `.__,' \         
                |        |         
                 \       /       /\
            ______( (_  / \______/ 
          ,'  ,-----'   |          
          `--{__________)