Unix recognizes 7 major filetypes. The file's type is stored in it's inode.

When a file is accessed, the Unix system uses the file's type to determine how or if the file may be accessed in the manor requested.

Regular file

• A regular file is a collection of bytes stored on the available storage device.
• How data is acted on is left to the program accesssing it.

• The 'directory' tag informs the Unix system which commands may access a directory 'file' and how it can be accesed.
• Stored on storage device like a regular file.
• Conceptually, an associative table of file-names and their associated inode index.

• Data file cotaining a string representing the [path/]file-name being linked to.
• Like the directory tag, the symbolic link instructs the Unix system on how this file can be accessed and interpreted.

• Actually, an interface pointer to a device driver that reads/writes information unbuffered. May be referred to as a raw device.
• Reads and writes should occur in real time.
• May or may not be able to access one character at a time. This depends on the device being accessed.
• Used by shell to read from the keyboard.

• An interface pointer to a device driver that reads/writed information with buffered interface.
• Used to access interface to the actual hard-drives taht provide storage.
• Because, reads/writes buffered, actual read/write to device may be delayed.
• See https://en.wikipedia.org/wiki/Device_file for a basic description.

• Functions the same as the |, pipe separator, execpt it can be addressed by name and using redirection.
• programs output can be redirected into a pipe and then retrieved from inside a separate child bash shell.

• Or retrieved from a named pipe and fed from with-in a child bash shell. # needs to be used with &, background process, for proper response.

  mkfifo listpipe1 mkfifo listpipe2 ls > listpipe1& bash cat < listpipe1 ... output from whatever is being fed in from the ls > cd bin ls > ../listpipe2& exit # back in initial shell. cat < listpipe2& ... should be the contents of the bin directory

  Or it can be fed from one the shell in one login and and fetched from with-in another login shell. Named pipes are one direction. Communication has to be on the same system. Data streamed as raw bytes. check out : http://www.linuxjournal.com/article/2156

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  Socket

  
  Sockets are the final filetype. 
  
    Much more advanced version of named-pipe.
  
    Used to communicate between processes on a system.
  
    Can be bi-directional.
  
    Supports packet or datagram style communication.
  
    Implemented in code, such as C.
  
    Usually consist of a 'server' program that constantly listens for 
      'client' requests to connect to it.
  
    And any number 'clients' may talk with a 'server'.
  
    Implimentation similar to networking, 
      except rather than an IP# or network Mac#
        the named socket 'file' is the interface between clients and server.