elisp: Process Type

 
 2.4.8 Process Type
 ------------------
 
 The word “process” usually means a running program.  Emacs itself runs
 in a process of this sort.  However, in Emacs Lisp, a process is a Lisp
 object that designates a subprocess created by the Emacs process.
 Programs such as shells, GDB, ftp, and compilers, running in
 subprocesses of Emacs, extend the capabilities of Emacs.  An Emacs
 subprocess takes textual input from Emacs and returns textual output to
 Emacs for further manipulation.  Emacs can also send signals to the
 subprocess.
 
    Process objects have no read syntax.  They print in hash notation,
 giving the name of the process:
 
      (process-list)
           ⇒ (#<process shell>)
 
    SeeProcesses, for information about functions that create,
 delete, return information about, send input or signals to, and receive
 output from processes.