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(librep.info)Process States

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Process States
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   Each process object has a "state" associated with it; this depends on
the status of the subprocess currently running on the process object (or
not as the case may be).

   The possible states are,

"running"
     This state means that the subprocess using this process object is
     currently running, i.e. it hasn't been stopped.

"stopped"
     Means that the subprocess has been temporarily suspended from
     running.

"unused"
     This means that the process object is free to have a new
     subprocess created on it.

   Predicates exist which test whether a given process object is in one
of these states.

 - Function: process-running-p process-object
     Returns true when PROCESS-OBJECT is in the running state.

 - Function: process-stopped-p process-object
     Returns true when PROCESS-OBJECT is in the stopped state.

 - Function: process-in-use-p process-object
     Returns true when PROCESS-OBJECT is _not_ in the unused state.

   The following two functions are used to stop and then subsequently
continue a process running.

 - Function: stop-process process-object #!optional whole-group
     This function suspends execution of the subprocess running on the
     process object PROCESS-OBJECT.

     If WHOLE-GROUP is true all subprocesses in the process group of
     PROCESS-OBJECT are stopped.

 - Function: continue-process process-object #!optional whole-group
     Use this function to continue a subprocess executing after it has
     been stopped (by the `stop-process' function).

     If WHOLE-GROUP is true all subprocesses in the process group of
     PROCESS-OBJECT are continued.

   The state change function component of a process object defines a
function which will be called each time the state of the process object
changes. If your program needs to be informed when an asynchronous
process terminates this function is the way to do it.

 - Function: process-function process
     Returns the value of the state change function component of the
     process object PROCESS.

 - Function: set-process-function process function
     Sets the value of the state change function component of the
     process object PROCESS to the function FUNCTION, then returns
     FUNCTION.