elisp: Process Type
2.4.8 Process Type
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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>)
Processes, for information about functions that create,
delete, return information about, send input or signals to, and receive
output from processes.