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(elisp)Process Information

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Process Information
===================

   Several functions return information about processes.
`list-processes' is provided for interactive use.

 - Command: list-processes
     This command displays a listing of all living processes.  In
     addition, it finally deletes any process whose status was `Exited'
     or `Signaled'.  It returns `nil'.

 - Function: process-list
     This function returns a list of all processes that have not been
     deleted.

          (process-list)
               => (#<process display-time> #<process shell>)

 - Function: get-process name
     This function returns the process named NAME, or `nil' if there is
     none.  An error is signaled if NAME is not a string.

          (get-process "shell")
               => #<process shell>

 - Function: process-command process
     This function returns the command that was executed to start
     PROCESS.  This is a list of strings, the first string being the
     program executed and the rest of the strings being the arguments
     that were given to the program.

          (process-command (get-process "shell"))
               => ("/bin/csh" "-i")

 - Function: process-id process
     This function returns the PID of PROCESS.  This is an integer that
     distinguishes the process PROCESS from all other processes running
     on the same computer at the current time.  The PID of a process is
     chosen by the operating system kernel when the process is started
     and remains constant as long as the process exists.

 - Function: process-name process
     This function returns the name of PROCESS.

 - Function: process-contact process
     This function returns `t' for an ordinary child process, and
     `(HOSTNAME SERVICE)' for a net connection (Note: Network).

 - Function: process-status process-name
     This function returns the status of PROCESS-NAME as a symbol.  The
     argument PROCESS-NAME must be a process, a buffer, a process name
     (string) or a buffer name (string).

     The possible values for an actual subprocess are:

    `run'
          for a process that is running.

    `stop'
          for a process that is stopped but continuable.

    `exit'
          for a process that has exited.

    `signal'
          for a process that has received a fatal signal.

    `open'
          for a network connection that is open.

    `closed'
          for a network connection that is closed.  Once a connection
          is closed, you cannot reopen it, though you might be able to
          open a new connection to the same place.

    `nil'
          if PROCESS-NAME is not the name of an existing process.

          (process-status "shell")
               => run
          (process-status (get-buffer "*shell*"))
               => run
          x
               => #<process xx<1>>
          (process-status x)
               => exit

     For a network connection, `process-status' returns one of the
     symbols `open' or `closed'.  The latter means that the other side
     closed the connection, or Emacs did `delete-process'.

 - Function: process-exit-status process
     This function returns the exit status of PROCESS or the signal
     number that killed it.  (Use the result of `process-status' to
     determine which of those it is.)  If PROCESS has not yet
     terminated, the value is 0.

 - Function: process-tty-name process
     This function returns the terminal name that PROCESS is using for
     its communication with Emacs--or `nil' if it is using pipes
     instead of a terminal (see `process-connection-type' in Note:
     Asynchronous Processes).

 - Function: process-coding-system process
     This function returns a cons cell describing the coding systems in
     use for decoding output from PROCESS and for encoding input to
     PROCESS (Note: Coding Systems).  The value has this form:

          (CODING-SYSTEM-FOR-DECODING . CODING-SYSTEM-FOR-ENCODING)

 - Function: set-process-coding-system process decoding-system
          encoding-system
     This function specifies the coding systems to use for subsequent
     output from and input to PROCESS.  It will use DECODING-SYSTEM to
     decode subprocess output, and ENCODING-SYSTEM to encode subprocess
     input.