37. Processes

In the terminology of operating systems, a process is a space in which a program can execute. Emacs runs in a process. Emacs Lisp programs can invoke other programs in processes of their own. These are called subprocesses or child processes of the Emacs process, which is their parent process.

A subprocess of Emacs may be synchronous or asynchronous, depending on how it is created. When you create a synchronous subprocess, the Lisp program waits for the subprocess to terminate before continuing execution. When you create an asynchronous subprocess, it can run in parallel with the Lisp program. This kind of subprocess is represented within Emacs by a Lisp object which is also called a "process". Lisp programs can use this object to communicate with the subprocess or to control it. For example, you can send signals, obtain status information, receive output from the process, or send input to it.

Function: processp object

This function returns t if object is a process, nil otherwise.

37.1 Functions that Create Subprocesses		Functions that start subprocesses.
37.2 Shell Arguments		Quoting an argument to pass it to a shell.
37.3 Creating a Synchronous Process		Details of using synchronous subprocesses.
37.4 Creating an Asynchronous Process		Starting up an asynchronous subprocess.
37.5 Deleting Processes		Eliminating an asynchronous subprocess.
37.6 Process Information		Accessing run-status and other attributes.
37.7 Sending Input to Processes		Sending input to an asynchronous subprocess.
37.8 Sending Signals to Processes		Stopping, continuing or interrupting an asynchronous subprocess.
37.9 Receiving Output from Processes		Collecting output from an asynchronous subprocess.
37.10 Sentinels: Detecting Process Status Changes		Sentinels run when process run-status changes.
37.11 Transaction Queues		Transaction-based communication with subprocesses.
37.12 Network Connections		Opening network connections.